Open Shelf-Life Dating of Food

August 1979

NTIS order #PB80-101629

Library of Congress Catalog Card Number 79-600128

For sale by the Superintendent of Documents, U.S. Government Printing OfficeWashington, D.C. 20402 Stock No. 052-003 -00694-4

In this study OTA addressed the practicality of open shelf-life dating of foodto disclose food freshness to the consumer. The assessment was undertaken at therequest of the Senate Committee on Commerce, Science, and Transportation.

The Office of Technology Assessment formed a panel of consumer represent-atives, food retailers, processors, wholesalers, scientific experts, and State andFederal Government officials. Staffs of the Congressional Research Service, theU.S. Department of Agriculture, and the Food and Drug Administration providedbackground information to the assessment. Individual papers and reports werecommissioned concerning the scientific basis for open dating of food and the crit-ical issues involved. A nationwide mail survey was conducted to gain the con-sumer’s perspective. In addition, reviews of the draft reports were provided byFederal agencies and officials, and a wide spectrum of interested individuals.

These wide-ranging contributions were vital to the shaping of the assessmentand to developing congressional options. To all of these people OTA acknowledgesa deep debt of gratitude; however, the report is an OTA staff synthesis and doesnot necessarily reflect the position or views of any particular individual.

JOHN H. GIBBONSDirector

ill

OTA Open Shelf-Life Dating of Food Advisory Panel

Jane AndersonDirector of Consumer AffairsAmerican Meat Institute

Jules BauermannDirector of Food TechnologyH. W. Longacre, Inc.

Lowrie M. BeachamSpecial Advisor to the PresidentNational Food Processors

Association

John BennettChief, Weights and Measures

DivisionDepartment of Consumer

ProtectionState of Connecticut

Judy Braiman-LipsonPresidentEmpire State Consumers

Association

Chambers BrysonChief, Food and Drug SectionDepartment of HealthState of California

Mahlon BurnetteDirector of Scientific AffairsGrocery Manufacturers of

America

*Carl D’AlessandroAssistant to the AdministratorFood Safety and Quality ServiceU.S. Department of Agriculture

John DeMossExecutive DirectorVirginia Food Dealers Association

John FarquharVice President, Education and

TechnologyFood Marketing Institute

G. William FouseChief, Division of Milk SanitationBureau of Foods and ChemistryDepartment of AgricultureCommonwealth of Pennsylvania

Michael J. Phillips, ChairmanOTA Project Director

Edward HeffronChief, Food Inspection DivisionDepartment of AgricultureState of MichiganHerman KammermanDirector, Office of Consumer

AffairsCity of Cleveland, OhioJames KirkChairman, Department of Food

Science and Human NutritionUniversity of FloridaGary KushnerAttorney at LawLeighton, Conklin, and LemovTheodore LabuzaProfessor, Department of Food

Science and NutritionUniversity of Minnesota*Jeffrey OdumStaff AssistantCommittee on Laws and

RegulationsNational Conference on Weights

and MeasuresNational Bureau of StandardsAmihud KramerProfessor, Department of

HorticultureUniversity of MarylandDarryl LundProfessor, Department of Food

ScienceUniversity of Wisconsin

Roy MartinDirector of Science and

TechnologyNational Fisheries InstituteStan McHughVice PresidentAmerican Bakeries CompanyGeorge MichaelDirector, Division of Food and

DrugsDepartment of Public HealthCommonwealth of Massachusetts

Sharon MorgansternAssistant to the PresidentNational American Wholesale

Grocers Association

Daniel PadbergChairman, Department of

Agricultural EconomicsUniversity of Illinois

*Taylor QuinnAssociate Director of ComplianceBureau of FoodsFood and Drug AdministrationU.S. Department of Health,

Education, and Welfare

Austin RhoadesAdministrative AssistantMilk Industry Foundation and

International Association ofIce Cream Manufacturers

Morton ShaevelVice President for Research and

DevelopmentFreezer Queen Foods, Inc.

Gary SmithProfessor, Department of Animal

ScienceTexas A&M University

Jeri Smith-FornaraArizona Consumers Council

Tom SporlederProfessor of Agricultural

EconomicsTexas A&M University

Joe SuiterAssistant SupervisorDairy and Food DivisionState of Washington

Dale WatsonVice President for Produce

MerchandisingGreat A&P Tea Company

Ruth YannattaCalifornia Citizens Action Group

*Ex officioNOTE: The Advisory Panel provided advice and comment throughout the assessment, but does not necessarily

approve, disapprove, or endorse the report for which OTA assumes full responsibility.

iv

OTA Open Shelf-Life Dating of Food Staff

Joyce C. Lashof, Assistant DirectorHealth and Life Sciences Division

J. B. Cordaro, Food and Renewable Resources Group Manager*

Walter Parham, Food and Renewable Resources Group Manager

Michael J. Phillips, Project Director

Phyllis Balan Elizabeth Galloway Yvonne Noel

Robert L. Smith, Jr. Ray Hoehle

Contractors and Consultants

Theodore P. Labuza Thomas L. Sporleder

Amihud Kramer James Kirk Dorothy Mayes

Department of Food and Nutrition, University of Minnesota

Leighton, Conklin, and Lemov

Market Facts, Inc.

OTA Publishing Staff

John C. Holmes, Publishing Officer

Kathie S. Boss Joanne Heming

*Through June 16, 1979.

OTA Food Advisory Committee

David CallDean, College of Agriculture

and Life SciencesCornell University

Cy CarpenterPresidentMinnesota Farmers Union

Eliot ColemanDirectorCoolidge Center for the

Study of Agriculture

Almeta Edwards FlemingSocial Program CoordinatorFlorence County, S.C.

Martin E. Abel, ChairmanSenior Vice President, Schnittker Associates

Johanna Dwyer, Vice ChairmanDirector, Frances Stern Nutrition Center

Lorne GreeneChairman of the BoardAmerican Freedom From

Hunger Foundation

Richard L. HallVice President, Science and

TechnologyMcCormick & Company, Inc.Laura HeuserMember, Board of DirectorsAgricultural Council of AmericaArnold MayerLegislative RepresentativeAmalgamated Meat Cutters and

Butcher Workmen of NorthAmerica

Max MilnerExecutive DirectorAmerican Institute of Nutrition

Robert O. NesheimVice President, Science and

TechnologyThe Quaker Oats Company

Kathleen O* ReillyDirectorConsumer Federation of America

R. Dennis RouseDean, School of AgricultureAuburn University

Lauren SethAgricultural Consultant

Thomas SporlederProfessor of Agricultural

EconomicsTexas A&M University

Sylvan WittwerDirector and Assistant DeanCollege of Agriculture and

Natural ResourcesMichigan State University

NOTE: The Food Advisory Committee provided advice and comment throughout the assessment, but does notnecessarily approve, disapprove, or endorse the report for which OTA assumes full responsibility.

vi

Contents

Chapter PageI.

II.

III.

Iv.

v .

Executive Summary . . . . . . . . . . . . . . . .Consumer Concerns . . . . . . . . . . . . . . . .Background. . . . . . . . . . . . . . . . . . . . . . .

State Practices . . . . . . . . . . . . . . . . . .Practices in Other Countries ., . . . . .

Findings and Conclusions. . . . . . . . . . . .Overall Findings . . . . . . . . . . . . . . . . .Specific Findings . . . . . . . . . . . . . . . .

Benefits. ...,. . . . . . . . . . . . . . . . .costs . . . . . . . . . . . . . . . . . . . . . . . .Open-Dating Techniques . . . . . . . .Criteria in Establishing Open DatesEnforcement and Liability . . . . . . .

Congressional Options . . . . . . . . . . . . . .Voluntary System . . . . . . . . . . . . . . . .Mandatory System . . . . . . . . . . . . . . .

Congress Specifies the Detail. . . . .Leave Implementation of Detail

to Others . . . . . . . . . . . . . . . . . . .Voluntary/Mandatory System , ., ., .

Consumer Perspective on Open Dating.Attitudes Toward Open Dating . . . . . . .Understanding Open Dates . . . . . . . . . .Preference Among Open Dates . . . . . . .Differences Among Subgroups of

Shoppers. . . . . . . . . . . . . . . . . . . . . . .

Benefits of Open Dating. . . . . . . . . . . . .Food Quality.. . . . . . . . . . . . . . . . . . . . .Nutrition. . . . . . . . ..., . . . . . . . . . . . . .Food Safety.,.. . . . . . . . . . . . . . . . . . . .Inventory Control. . . . . . . . . . . . . . . . . .Education , . . . . . . . . . . . . ..., . . . . . . .

Alternative Open-Dating Techniques . .Method of Open Dating. , . . . . . . . . . . . .

Pack Date . . . . . . . . . . . . . . . . . . . . . .Sell-by and Best-if-Used-by Dates. . . .To Remain in Grade Use-(Sell-)

by Date . . . . . . . . . . . . . . . . . . . . . .Combination Dates . . . . . . . . . . . . . . .

Implementation, . . . . . . . . . . . . . . . . . . .Storage Instructions. . . . . . . . . . . . . .Type of Date Marking. . . . . . . . . . . . .

Exemptions. . . . . . . . . . . . . . . . . . . . . . .

Establishing Open Dates . . . . . . . . . . . .Alternative Criteria . . . . . . . . . . . . . . . .

Sensory Quality . . . . . . . . . . . . . . . . .Nutrient Loss . . . . . . . . . . . . . . . . . . .Perishability Time Categories . . . . . .

Scientific Tests and Data Needed . . . . .Impact on Technology Development . . .

11333555566778899

1011

13131415

18

192020212121

23232324

262627272728

31343435363637

Chapter PageVI. Alternative Open-Dating Systems . . . . . 39

Voluntary System, .., . . . . . . . . . . . . . . 39Mandatory System.,. . . . . . . . . . . . . . . 39Voluntary/Mandatory System . . . . . . . . 41

VII. Enforcement and Liability . . . . . . . . . . . 43Methods o fEnforcement . . . . . . . . . . . . 43

Before-Date Enforcement . . . . . . . . . . 43Beyond-Date Enforcement . . . . . . . . . 44

Federal/State Enforcement . . . . . . . . . . 45Liability, . . . . . . . . . . . . . . . . . . . . . . . . . 46

Liability Under the Food, Drug, andCosmetic Act . . . . . . . . . . . . . . . . . 46

Civil Liability. .,..... . . . . . . . . . . . . 47

VIII. Economic and Social Costs . . . . . . . . . . . 49Costs of Open Dating . . . . . . . . . . . . . . . 49

Establishing Shelf Life. . . . . . . . . . . . 49Dating the Package. . . . . . . . . . . . . . . 49Enforcement ..,..,.. . . . . . . . . . . . . 49Comparison With Nutrition Labeling. 50

Impact. . . . . . . . . . . . . . . . . . . . . . . . . . . 50Processors, . . . . . . . . . . . . . . . . . . . . . 50Wholesalers and Retailers . . . . . . . . . 50Consumers . . . . . . . . . . . . . . . . . . . . . 50Government . . . . . . . . . . . . . . . . . . . . . 51

IX. Array of Congressional Options . . . . . . 53Congressional Options . . . . . . . . . . . . . . 53

AppendixesA.

B.

c.

D.

E,

LIST

Application of Open Dating toSpecific Foods . . . . . . . . . . . . . . . . . . . 59

Basic Food Preservation andDeterioration Modes. , . . . . . . . . . . . . 77

Technological Evaluation of Shelf Lifeof Foods. ,. ....., . . . . . . . . . . . . . . . 87

Status of Open Shelf-Life DatingRegulations for Selected Countriesand International Food LabelingOrganizations, 1978. . . . . . . . . . . . . . 103

Bibliography, . . . . . . . . . . . . . . . . . . . . . 105

OF TABLES

Table No. Page1. Summary of Open-Date Labeling

Requirements by States, 1978 . . . . . . . . 42. Consumer Usefulness of Information on

Food Packages . . . . . . . . . . . . . . . . . . . . 143. Consumer Understanding of Freshness

Dates. . . . . . . . . . . . . . . . . . . . . . . . . . . . 144. Consumer Preferences for Open Dates. 15

vii

Table

5.

C-1 .

LISTFigure

No. Page

Major Modes of Deterioration, CriticalEnvironmental Factors. Shelf Life, andType of Open Dating by Food Product . . 32Weeks of Shelf Life at a GivenTemperature for Given Q10. . . . . . . . . , . 93

OF FIGURESNo. Page

1. Example of Interaction of CongressionalOptions . . . . . . . . . . . . . . . . . . . . . . . . . . 54

B-1. Moisture Content v. Water Activity. . . . 83B-2. Effect of aw on Rate. . . . . . . . . . . . . . . . . 83C-I. Nomogram of Temperature, Time, and

Quality for the Military Ration ItemsUsed in the Long-Term Storage Tests ., 88

Figure No. Page

C-2.C-3.C-4.C-5,

C-6.C-7.C-8.C-9.C-l0.C-1 1.

C-12C-13.C-14.

Constant Shelf Life Lost . . . . . . . . . . . . . 90First-Order Degradation . . . . . . . . . . . . 90First-Order Log Plot . . . . . . . . . . . . . . . . 91Initial Quality Gain Prior to First-OrderDegradation . . . . . . . . . . . . . . . . . . . . . . 91Shelf-Life Plot .....,... . . . . . . . . . . . . 92Temperature/Time History . . . . . . . . . . 93Sequential Regular Fluctuating Profile. 95Moisture Gain. . . . . . . . . . . . . . . . . . . . . 97Storage Conditions . . . . . . . . . . . . . . . . . 98Shelf Life as a Function of aW andTemperature. .,..... . . . . . . . . . . . . . . 99Calculated Moisture Content v. Time. . . 100Senescence Rate as a Function of O, ., . 101Rates of Permeation and RespirationOf oz. . . . , , . . , . . . . . . . . , . . . . . , . . . . . 101

. . .Vlll

Executive

Chapter I

Summary

In their concern over the freshness of food, consumers have increasinglyadvocated open shelf-life dating—the use of dates on a can or package of foodthat gives the consumer some idea of when a product was packed or should besold or used. Although such a step appears simple and sensible at first glance, itentails many scientific and financial uncertainties and involves some complexchoices.

The Senate Committee on Commerce, Science, and Transportation askedOTA to assess the feasibility of open shelf-life dating of food and to provide Con-gress with the necessary information to adequately address this area of foodlabeling.

This assessment analyzes: consumers’ perspectives on open-date labeling;benefits and costs; alternative systems and techniques; alternative criteria andscientific tests to establish open dates; enforcement mechanisms and liability re-lated to open-date labeling; and options available to Congress.

CONSUMER CONCERNSEver since the vast majority of Americans

became urbanized, consumers have had nosure way of knowing how fresh their foodreally is. Since they did not grow it them-selves or personally know such factors as itsage or storage condition, they have had torely on assurances that wholesalers and re-tailers were abiding by some system thatwould eliminate food that was no longerfresh. Fresh food refers to food in which thequality has been unchanged from its initialstate. Even under ideal conditions some foodslose their freshness within 2 or 3 days of be-ing packed, while other foods may remainfresh for over a year,

survey in 1971 showed that 20 percent hadcomplaints about food product freshness; aNielson survey in 1973 turned up 50 percentwith such complaints. A 1978 survey furthersupported this concern by noting that of allthe problems on the minds of consumerswhen they shop for food, making sure thatfood in supermarkets is fresh heads the list. ’

Facts that lend support to such concernsare scarce, however. There are no nation-wide statistics on the amount of food sold thatis not fresh, although there have been someindividual State studies that indicate there isa problem.

Recent studies have shown that, indeed,ISkeIly Yankelovich, and White, Inc., “A Study of

consumers are concerned over whether or Consumers’ Attitudes and Behaviors Towards Eating atnot the food they purchase is fresh. A U.S. De- Home and Out of Home,” Woman’s Day, Family Foodpartment of Agriculture (USDA) consumer Study, 1978.

1

2 . Open Shelf-Life Dating of Food

For example, a study of 25 supermarkets inMinnesota showed that all of those stores hadsome outdated food on their shelves.2 Anotherstudy in that State found that 44 percent ofthe baby formula being sold was over age andthat since 64 percent of the store managerscould not read a coded date, they could notrotate the stock.3 These findings led the Stateto adopt mandatory open shelf-life dating forsome foods.

Open shelf-life dating means the use of legi-ble terms such as a day, month, and year asan indication of when the food was packagedor by when it should be sold or used. Suchdating is considered by most people to be ameasure of food freshness. It does inform thebuyer about the time lapse between packag-ing and purchase or use and, to the extentthat such time lapse is synonymous with qual-ity loss, of the quality or freshness as well.However, such a time lapse is not necessarilythe only factor leading to quality loss—i.e.,deviation from freshness. Therefore, an opendate is not an absolute assurance of fresh-ness—but it can be an indication.

Dating of food is far from being a new con-cept—in fact, it started back in the early1930’s. However, the dates have usually beenin coded form, based on a color-keyed or num-ber/letter system. The codes were originallydesigned to aid in controlling food inventoriesand to assist in any product recalls, such asfor contaminated foods.

Consumers complain that since they cannotinterpret the codes, they cannot tell whetheror not the food they are buying is fresh. In-deed, sometimes employees at both the retailand wholesale level cannot read the codeseither and thus are unable to use them as ameans of keeping stocks in-date.

All indications are that consumers do wantdates they can understand. For example, in

‘Minnesota Public Interest Research Group, “Surveyof Minnesota Food Stores, 1972, ” testimony before theMinnesota State Senate on Open Dating Legislation.

‘Keith Ford, Minnesota Office of Consumer Services,testimony before the Minnesota State Senate Hearingson Open Dating Legislation, 1972.

1977 the New York Consumer ProtectionBoard published a report translating foodmanufacturers’ freshness codes. The Boardreceived over 100,000 requests for copies ofthe report.

Currently, no Federal policy exists on opendating. There is wide variation among the 21States and the District of Columbia that havesome form of mandatory open dating. For ex-ample, different States require differentproducts to be dated, require different datesfor the same products, and the same datescan have different interpretations. In addi-tion, none of the States seem to have done“before and after” studies of open dating.

Even where not required by State law,some manufacturers have chosen to volun-tarily open date their products. However,since there are no industry guidelines, thereis no uniform system.

The result is often consumer confusion. Forexample, a survey conducted for OTA showsthat three out of four consumers can correct-ly identify the type of date on milk. But onlyone in four knows the type of date on break-fast cereal, and only one in three knows thetype of date on ground beef. Of course, milk ismore often open dated than are breakfastcereal and ground beef.

To further complicate matters, there is noscientific body of knowledge to accuratelydetermine dates for various products, no con-sensus on which type of date or dates—“pack” (when food was processed or pack-aged for retail sale), “sell by” (the last date afood product should be sold), “best-if-used-by” (the date after which food is no longer atits most acceptable level of quality), or a com-bination of these—to use for which product,or even which products to date at all, and noreal guidelines as to how to display the date.

What appears at first to be a simple task ofconverting code to open dates readily be-comes complex with many unanswered ques-tions.

Even though no action has been taken atthe Federal level, there has been and contin-

Chapter /—Executive Summary ● 3

ues to be much congressional and executive and the Federal Trade Commission on foodagency interest in open dating. Bills have labeling issues. Over 9,000 written responsesbeen introduced in the U.S. Congress on food were received, 5,000 of which were from con-labeling that would require open dating. sumers. Preliminary results of the consumerHowever, only the Senate has approved such responses indicate that consumers do wantlegislation, some form of open dating,

In 1978, joint hearings were conducted bythe Food and Drug Administration, USDA,

BACKGROUNDState Practices

Some form of open-date labeling is re-quired in 40 percent of the States, includingthe District of Columbia (table 1). But morerevealing than the number of States that haveopen dating are the food products coveredand the type of date used.

Perishable foods, such as fluid milk, arethe most common food products open dated.In 21 States with some form of mandatoryopen dating, 12—or 60 percent—have lawslimiting coverage to fluid milk and/or milkproducts. *

Open-dating laws or regulations in sevenStates and the District of Columbia apply to abroader class of food products. One State,Massachusetts , includes both perishablesand nonperishables, or long shelf-life foods.

The type of date used varies by State, butthe majority either require or suggest a sell-by date, which is the last date a food productshould be sold. Seventeen States and the Dis-trict of Columbia fall into this category.

There is some variation among the States,however, in the requirement for sell-by dates—particularly for fluid milk and/or milk prod-ucts. For example, the New Mexico lawstates that fluid milk and cream containersshall be labeled “with a legible sell-by date

*Perishable foods have a short shelf life, usually lessthan 30 days. Semiperishable foods have a shelf life ofbetween 1 and 6 months. Nonperishable or long shelf-life foods have a shelf life of more than 6 months,

not to exceed 14 days including the date ofpackaging for pasteurized products and 5days for raw products. ” By contrast, theMaryland law requires all pasteurized milkproducts to have the term “sell by, ” which isdesignated as a date “7 days after the day ofpasteurization. ”

In addition to the 21 States requiring someform of open dating, some food manufac-turers voluntarily open date their products,Some use a pack date, others a sell-by date,and still others a use-by or best-if-used-bydate. Some explicitly indicate that it is a sell-by or use-by date, while others only show adate.

Therefore, in some areas of the country, aportion of the food supply has some type ofopen date, while in other areas, food does notcarry any date. Even among the States re-quiring open dating, the same date can havedifferent interpretations. And in voluntaryopen dating by industry, there is no guidanceas to: 1) which products to date, 2) which dateto use, 3) how to display the date, and 4) howto scientifically determine the date. In sum,there is no uniform system.

Practices in Other Countries

In contrast, many other countries and in-ternational organizations have establishedrequirements for dating of food products. Forexample, open dating, with or without codedating, is mandatory for prepackaged con-

4 . Open She/f-Life Dating of Food

Table 1.--Summary of Open-Date Labeling Requirements by States, 1978

Form of EffectiveState/locale Primary products open date since about

Alabama . . . . . . . . . . . . . . . . . . . DairyCalifornia . . . . . . . . . . . . . . . . . . Dairy .Connecticut . . . . . . . . . . . . . . . . MilkDistrict of Columbia . . . . . . . . .Perishable productsFlorida . . . . . . . . . .. . . . . . . . . . DairyGeorgia . . . . . . . . . . . . . . . . . . . . Milk, eggsMaryland . . . . . . . . . . . . . . . . . . . MilkMassachusetts. . . . . . . . . . . . .Perishable & long

shelf lifeMichigan. ....,.. .. .. .. .. .. . Perishable productsMinnesota . . . . . . . . . . . . . . . . .Perishable products

with shelf life<90daysNebraska . . . . . . . . . . . . . . . . . .EggsNevada . . . . . . . . . . . . . . . . . . . . DairyNew Hampshire. .. .. ... ... ..CreamNew Jersey. . . . . ,. .. ... ... ..DairyNew Mexico. . . . .. ... ... ... .MilkOhio . . . . . . . . . . . . . . . . . . . . . .Perishable productsOklahoma . . . . . . . . . . . . . . . . . . Meat, eggsOregon . . . . . . . . .. .. .. .. .. .. Perishable productsPennsylvania . . . .. ... ... ... .MilkVirginia . . . . . . . . . .. .. .. .. .. .Dairy & infant formulaWashington . . . . . .. .. .. .. .. . Dairy & othersWisconsin . . . . . . . . . . . . . . . . . Smoked fish

Sell-bySell-bySell-bySell-bySell-bySell-bySell-bySell-byor

use-bySell-bySell-by or

use-byPackSell-byUse-bySell-bySell-bySell-bySell-byPack or sell-bySell-bySell-bySell-byPack

1975197319731974197619731971

1979b

1969

1973—

19731973

—19771977

19751975197419741971

~hisreguiationispresentfybeing chaiiengedincouft.bl~g~r~h~ief~~; l~forff~~foods;and Iwl forremaining long shelf-life foods. These dates maychangede-pendingontheoourt’sdecision concerningthelagetityoftheregulation.

SOURCE:OTAsurvey.

sumer food items expected to have a shortshe l f l i f e in p rac t i ca l ly a l l deve lopedcountries—with the United States a notableexception. In the developing countries, thesame trend applies, particularly for foods in-tended for export, except that open dating isnot confined to short shelf-life items.

Some other countries have already movedfrom simply code dating to open dating forlong-life products. For example, Japan, Vene-zuela, and Sweden, while allowing codes, re-quire that the pack date also appear in an“open’’ form.

The Codex Alimentarius Commission, theglobal organization for food-labeling stand-ards, states a general preference for opendates but requires them only on infant’s andchildren’s foods. The European EconomicCommunity recently adopted open dating fornearly all food products, with some excep-tions. (See appendix D for a breakdown ofopen dating throughout the world.)

In view of these international develop-merits, the lack of a U.S. policy on open datingcould cause problems and lead to confusion infuture food trade. Therefore, the issue ofopen dating has international as well as do-mestic implications.

Chapter I—Executive Summary ● 5

FINDINGS AND

Overall Findings. -1 . 1 ..,1 .1

1.

2.

3.

4.

5.

There is little evidence to support or tonegate the contention that there is a di-rect relationship between open shelf-lifedating and the actual freshness of foodproducts when they are sold.

The pressure for open shelf-life datingcomes from a consumer perception thatsuch dating ensures food freshness andthat industry should disclose its codeddates.

Deterioration in food quality is affectedby environmental factors such as tem-perature, humidity, and light in relationto t ime. Ideally, dating informationshould reflect on these factors, but thetechnology to measure their influence in-expensively is in various stages of devel-opment and is not likely to be applicablein the near future,

Open dating is applicable for all foodcategories because all foods deteriorate.For most perishable and semiperishablefoods the major modes of deteriorationcause sensory quality loss such as colorloss or off-flavor development, whichcan be easily recognized. For long shelf-life products, a major mode of deteriora-tion is nutrient loss, such as vitamins Aor C, which cannot be recognized by con-sumers. In addition, most long shelf-lifefoods are packaged such that it is notpossible to examine contents for sensoryquality loss before purchase.

Information gaps exist on: a) the amountof food sold nationally that is not fresh,b) the experience of States that have ini-tiated open-dating programs, c) the sci-entific base to determine and monitor afreshness date, and d) the costs of opendating on a product-specific basis.

CONCLUSIONS

Specific Findings

Benefits

1.

2.

3.

4.

Open dating encourages better handlingpractices by wholesalers, retailers, andconsumers by expediting the sale or useof food near the end of shelf life. Thiscan result in a decrease of consumercomplaints about buying spoiled or stalefoods, Indeed, a USDA study found thatsuch complaints decreased by 50 per -cent af ter the introduction of opendating.

Open dating can increase consumer con-fidence in the freshness of food pur-chased. In the same study, USDA foundthat the reduction in consumer com-plaints about spoiled or stale foods wasreported for both open-dated and non-open-dated food in the same store. Ap-paren t ly , because in fo rmat ion wasavailable for some foods, shoppers hadmore confidence in the freshness of allfoods.

Better handling practices attributed toopen dating could minimize nutrient loss.A processor could estimate the length oftime the product would be in the distri-bution system and, given the environ-mental conditions, determine how thesefactors would affect the loss of unstablenutrients, such as vitamin C.

There is little or no benefit derived fromopen dating in terms of improved micro-biological safety of foods. For foods ingeneral, microbiological safety hazardsare a result of processing failures, con-tamination after processing, and abusesin storage and handling. These factorsare usually independent of the age of theproduct and have little relationship to anopen date,

6 ● Open Shelf-Life Dating of Food

Costs

Very little research has been done to deter-mine costs of open dating. These findings arebased on the best estimates of academic andindustry shelf-life experts and experience byindustry and Government with nutrition la-beling.

1. A major initial cost in adopting opendating is establishing a reliable date.Estimates are approximately $100,000for each perishable and semiperishablefood and $200,000 for each long shelf-life food (1979 dollars).

2. Major costs to wholesalers and retailerswould be for employee time to inspectshelves for out-of-date stock and thendispose of such stock.

3. Enforcement costs for the Federal Gov-ernment could vary from practicallynone to more than $500,000 per year, de-pending on the enforcement system andthe extent to which the system weremandatory.

4. Based on nutrition-labeling experience,total costs of adopting open dating wouldbe small on a per-dollar sales basis butnonetheless may add from 0.1 to 1 centto the cost of each package of food. In1975, the average cost of establishingnutrition information per dollar of saleswas .004 cents, and the average continu-ing cost of nutrition labeling, which in-volves complex testing procedures andmore information to be printed on thelabel than does open dating, was a min-imal amount—especially once it was es-tablished. The same should be true foropen-date labeling.

Open-Dating Techniques

There are many possibilities in convertingcodes to open dates. The date could be a packdate, sell-by date, best-if-used-by date, or acombination of these.

1. A pack date is the day, month, and yearthe food product was processed or pack-

aged for retail sale. It is of minimal valueto consumers in that it provides little in-formation as to freshness or how longproducts should remain at acceptablequality. A pack date is, however, theeasiest and least expensive for industryto implement.

2. A sell-by date is the last date a foodproduct should be sold in order to allowa “reasonable” length of time for con-sumer use. This date is appropriate forperishable foods such as milk and dairyproducts because they have a short shelflife. It is the most useful date for whole-salers and retailers in their inventorycontrol, since it states the last day ofsale. However, it does not indicate to theconsumer when foods should be used.Because it is currently being used onmany perishable foods, it could easily beimplemented by industry for productswith a short shelf life.

3. Best-if-used-by date is the date after

4

which food is no longer at its most ac-ceptable level of quality. It is the pre-ferred single date by consumers and pro-vides the most useful information onquality. It is more appropriate for foodsthat have a long shelf life. It is, however,the most difficult for wholesalers and re-tailers to use in inventory managementbecause they must subjectively deter-mine allowances for home storage inorder to determine the last day of sale.

This date is presently used on somesemiperishable and long shelf-life foods.However, the full implementation of thiskind of date may require as much as a 2-year period to scientifically establish itfor a given product at a cost of $200,000per product.Combination dates are preferred by con-sumers to single dates. They provide themost information, especially a sell-byand best-if-used-by combination. Combi-nation dates, however, have all of thedisadvantages of single dates.

Chapter /—Executive Summary . 7

Criteria in Establishing Open Dates

There are several criteria that can be usedto establish sell-by and best-if-used-by datesincluding: sensory quality, nutrient loss, anddegree of perishability,

1. Sensory quality, such as color, odor, andflavor, is the most discernible criteriafor establishing sell-by and best-if-used-by dates. For some foods, sensory qualitychange may also be an indicator of nutri-ent quality. However, regulatory agen-cies would probably not be able to usesensory criteria to determine whether afood that is still in date is out of com-pliance with some quality level, sincetests to determine whether a given prod-uct is of some designated sensory qualityrequire taste panels trained in specificareas. This is not applicable to regula-tory methods. However, if a physical orchemical method could be correlatedhighly with a sensory test, compliancetesting would be simplified.

2. Nutrient loss would be easier to meas-

3,

ure than would sensory quality, since itcan be done objectively in an analyticallaboratory. However, nutrient content ofthe same food commodity can vary; also,some foods are naturally poor in somenutrients, are not eaten to provide thosenutrients, and may be of good qualityeven if they lost a certain percentage ofthe nutrients. Thus, critical nutrient lossmethods are useful only where they arehighly correlated with overall sensoryquality losses,Perishability time categories, which es-tablish a date by a set number of daysafter processing, are more relevant forhighly perishable foods that have a mini-mum of processing, However, modernprocessing conditions and new types ofpackaging can increase the shelf life ofsome foods to the point where time cate-gories are not meaningful unless con-tinuously modified to reflect new cir-cumstances.

Enforcement and Liability

Open dating raises some unique problemsof enforcement and liability. Enforcement, forexample, raises two serious points: 1) en-forcement with respect to quality standardsin establishing the date and 2) sale of a prod-uct after the date. Liability in open datingpresents unique difficulties because mostother labeling requirements only involve theprocessor, but open dating involves whole-salers and retailers as well. This leads toquestions of who is ultimately liable andwhether existing law is adequate to deter-mine liability.

In general, the findings in these areas are:

1.

2.

3.

4.

5.

An enforcement system where proces-sors establish reasonable dates thatmust be approved by the appropriate ex-ecutive agency has many advantagesover a system where the enforcementagency performs the necessary labora-tory test to determine the validity ofopen dates. It is less expensive, wouldnot lead to a decline in quality specifica-tions for the date, and would avoid ques-tions of a processor’s liability.Consumer complaint-based enforcementfor products sold at full price after thestated date (i. e., the consumer complainsto the appropriate authority) is less cost-ly than Government agency inspectionfor out-of-date products and can be veryeffective,Some foods that are beyond date couldbe sold to consumers, perhaps at a re-duced price, because the foods will stillbe safe.Federal/State cooperation on enforce-ment is feasible. However, in order tohave each State enforce a Federal man-datory program, the Federal Govern-ment may have to provide 100 percent ofthe costs. If not, the States would preferenforcement at the Federal level.There have been no court decisions onthe questions of liability for deteriorated

8 c Open She/f-Life Dating of Food

food that has been open dated. If therewere a Federal requirement for opendating, the Federal Food, Drug, and Cos-metic Act (FDCA) seems to provideseveral mechanisms by which to ensurecompliance, especially as it relates toadulteration and misbranding. However,if literally interpreted, FDCA does notprovide for abuses to food products indistribution that could cause the date tobe involved. In addition, the meaning of asell-by date is somewhat vague. This

date suggests that the product can beconsumed for a reasonable period oftime after the date with no recognizabledifference in the food’s quality. Omis-sion of information disclosing the en-suing consumption period could consti-tute the omission of a material fact ren-dering the product misbranded. Theseareas should be specifically addressedin the legislative history of any open-dating provisions.

CONGRESSIONAL OPTIONS

There are three basic options for Congressto consider in the open-dating issue. Congresscan:

Allow the present voluntary system t ocontinue by taking no action. Under thissystem, the private food sector is devel-oping and adopting open-dating stand-ards.

~. Choose a mandatory system, w h i c hwould require the use of specific opendates.

3. Choose a voluntary/mandatory system,whereby the Federal Government devel-ops guidelines, and processors who electto open date are required to follow thoseguidelines.

If Congress chooses Options 2 and/or 3, itcan either specify the detail or leave it up toothers, such as an appropriate regulatoryagency or an industry association. In otherwords, Congress can legislate which type ofdates for which food and how those dates areto be determined, or it can delegate the task.

These options are not mutually exclusive.Congress can select one option, two options,or a combination of all three. For example,Congress can decide to leave open dating ofbulk fresh produce as is, under a voluntarysystem; make open dating of other perish-ables and semiperishables mandatory; andplace long shelf-life foods under a voluntary/

mandatory system. In addition, the type ofdate selected can vary by individual product.In short, many potential combinations exist(see chapter IX for a more detailed discus-sion).

Voluntary System

If Congress opts for the status quo, it willbe supporting a system in which the privatefood sector will presumably continue to devel-op and adopt open-dating standards.

Pros: The principal advantage to this sys-tem is that it allows processors flexibility indetermining whether or not to open date andminimizes the cost to the Federal Governmentand industry, compared with the other sys-tems. Moreover, under this approach 21States and the District of Columbia haveadopted open-dating laws over the past 8years and have done so with a minimumamount of regulatory control and enforce-ment.

This option would allow time for specificresearch to better gauge the cause-and-effectrelationship between open dating and spoil-age reduction. Specific areas in which fur-ther data is needed include: the amount andkinds of food sold nationally that are notfresh, better quantification of costs, and animproved scientific base to accurately deter-

Chapter l—Executive Summary ● 9

mine freshness dates, The experience ofStates that have adopted open shelf- l i fedating will be helpful in obtaining the abovedata.

Cons: The most serious perceived disad-vantage of this approach is the lack of uni-formity in deciding: 1) which products to date,Z) which date to use, 3) how to display thedate, and 4) what scientific guidelines shouldbe used to determine the date. In addition, in-ventory-control procedures are relativelymore difficult, which could result in morefood waste than under a mandatory system.Also, some industries may not adopt the pro-gram.

Mandatory System

A mandatory system would require the useof specific open dates.

Pros: The principal advantages of thissystem is that a mandatory system would pro-vide uniform regulations; tighten inventorycontrol, which could reduce food waste; pro-vide higher quality and nutritive levels formore food; and set criteria for calculating ac-curate open dates.

Cons: The principal disadvantage is that,with the exception of using a “pack date, ” itwould be difficult to implement in the shortrun of 2 to 5 years for semiperishable andlong shelf-life foods because of insufficientdata on shelf-life stability of these productcategories. However, since many perishableproducts are presently open dated, data areavailable to implement a mandatory systemfor perishables,

Other disadvantages would be: 1) costswould increase to Government for developingand enforcing regulations and to industry forcompliance, compared with a voluntary/man-datory system, 2) out-of-date products maybeusable but returned and wasted (unless spe-cial arrangements are made for their use), 3)development of regulations would be time-consuming for both Government and industry,4) innovation in terms of incentives to develop

new processing techniques to increase shelflife could be stifled, and 5) small processorscould be forced out of business.

If a mandatory policy is selected, Congressmust decide who should specify the tech-nique, criteria, and type of enforcement sys-tem. To specify these areas, there are twobasic ways Congress can legislate. Congresscan either specify the details itself or chargeothers with the responsibility for doing so.

Congress Specifies the Detail

Open-dating techniques. Congress couldspecify the use of one or a combination of thefollowing open-dating techniques: pack date,sell-by date, best-if-used-by date, or somecombination.

Pros: The advantages of a mandated tech-nique by product or product category includeuniformity in all States and less potential con-sumer confusion.

Cons: The disadvantages include:

It would be more difficult to change atechnique over time than if specifica-tions were left up to the appropriate reg-ulatory agency.A continuous legal and/or legislativeprocess may arise in an effort to changedates over time. This could be an expen-sive process for industry, Government,and ultimately for consumers.

Open-dating criteria. In addition, Congresscould decide which criteria must be used forwhich date or dates. In other words, whichcategories of sensory quality, nutrient loss,and perishability to use.

Pros: The advantage of mandating specificcriteria used in establishing dates includesstandardization among products and/or prod-uct categories.

Cons:

● Neither Congress nor the Secretary ofthe appropriate executive branch agen-cy currently may have the technical abil-ity and data necessary to specify criteriafor each food item.

49-394 0 - -9 - 2

10 . Open Shelf-Life Dating of Food

●

●

Technological innovation could be stifledbecause cri ter ia could not be easi lychanged.The criteria may not likely be based onsensory quality parameters because itwould be more difficult to regulate thanwould other criteria. This could be anadvantage for some products and a dis-advantage for others , depending onwhat test index is chosen.

An alternative to mandating specific cri-teria is to allow a range of criteria. The ad-vantage of mandating some range of criteriais that both sensory and nutritional criteriawould likely be included within the range.The disadvantage is that there would not bestandard criteria for similar products.

Enforcement and liability. Congress hastwo basic options for determining the en-forcement system and for establishing liabili-ty as it relates to open-date labeling:

●

●

Use Existing Laws

Pros—Enforcement: Allowing the exist-ing laws to specify enforcement simplifiesthe procedure and minimizes the cost andtime for both Government and industry.

Cons—Enforcement: Existing law doesnot specify what should be done in the caseof: a) food that is still edible but past dateand b) food that is beyond criteria but notpast date.

Pros—Liability: Existing laws coveringliabil i ty already offer several devicesthrough which manufacturers, wholesal-ers, and retailers might be held liable forviolations of an open-dating requirement.

Cons—Liability: Since there is no defini-tive legislative or judicial definition of thelegal significance of an open date, applica-tion of existing law remains speculative.

Pass New Laws

Pros—Enforcement: Legislating new en-forcement procedures has the advantageof allowing Congress to address specificitems such as use of State enforcement offi-

cials and/or complaint-based enforcementby consumers for beyond-date complianceand disposal of edible food that is out-of-date.

Cons—Enforcement: Writing a new lawto adequately provide for enforcement in-creases both time and cost to Governmentand industry.

Pros—Liability: Writing new legislationthat specifies liability and penalties, if any,for open-date labeling could provide con-sumers with more confidence in an open-date labeling system.

Cons—Liability: It is a difficult and bur-densome task to ascertain liability to thefirms responsible.

Leave Implementation of DetailtO Others

Delegating the specifics to either the ap-propriate executive agency or the privatesector would have the following results: 1) itrelieves Congress of the necessity to makethese determinations and 2) it would be easi-er to change a technique over time than ifspecifications were decided by Congress.

● Appropriate Executive Agency

—Open-Dating Techniques

Pros: The advantages of this option, aswith congressionall y mandated detail, in-clude uniformity of the open-dating tech-nique for all food processors producing asingle product. Also, the regulatory proce-dure would allow industry and consumersmore involvement than would the detailedstatutory approach.

Cons: The disadvantages of allowing ex-ecutive discretion include the potentiallylarge costs in time and money both Govern-ment and industry would incur before theregulations could be developed.

—Criteria

The advantages and disadvantages ofestablishing open-dating criteria are the

Chapter l—Executive Summary s 11

same for an executive agency as those dis-cussed for Congress.

● Private Sector

—Open-Dating Techniques

Individual processors could be allowedto choose the dating techniques and makethem defensible to the appropriate Secre-tary.

Pros: Allowing individual processors tohave this freedom would allow the market-place to determine the best system.

Cons:

● Lack of uniformity of date types on simi-lar products could confuse consumers andretailers.. The retailer may have problems usingopen dating for inventory control whenthere is a lack of uniformity on similarproducts.Ž Small processors may use pack datessince they might not be able to do the nec-essary research to establish sell-by or use-by dates.

As an alternative, an industry associa-t ion could be al lowed the freedom tochoose the dating techniques and makethem defensible to the appropriate Secre-tary.

Pros:

Ž Date types on similar products would beuniform.● Consumers could have input into indus-try association meetings to establish dates,especially if the association decision weresubject to Secretarial review.

Cons:

● If the system were voluntary/mandatory,it would allow nonmembers of the industryassociation to do nothing.Ž If mandatory and nonmembers of the in-dustry association have not had an oppor-tunity to participate in the process ofchoosing a technique for dating, this could

lead to legal problems such as antitrust orrestraint of trade.. There may be more than one industry as-sociation to which one processor belongs,and these associations might establish twodifferent techniques.

—Criteria

Pros: The advantages of allowing proc-essors to specify criteria for establishingopen dates include:

● Sensory criteria could be part of the in-put when considered appropriate for theparticular product.. Through the appropriate Secretary, con-sumers could have a continuing voice inwhat criteria is used.

Cons:

● Secretaries of the regulatory agenciesinvolved would have an additional burdenof reviewing the criteria submitted to them.Ž Costs to Government could be quite highrelative to other options.

Voluntary/Mandatory System

A voluntary/mandatory system is one inwhich the Federal Government developsguidelines, and processors who choose toopen-date food products are required tofollow these guidelines.

Pros: This system establishes a mechanismfor uniformity to open-date food products,and it provides individual food processors thebasic option of determining whether or not toopen-date products.

Cons: Costs to Government would increasefor developing and enforcing regulations andto industry for compliance. Development ofregulations would be time-consuming for bothGovernment and industry.

Note that if the Congress chooses this op-tion path, the issues discussed under the man-datory system become relevant.

Chapter II

Consumer Perspective onOpen Dating

thisSince consumers are the ultimate users of open dating, an integral part ofassessment is consumer interest in and perspective on open dates for food.

The background for this section comes from an Office of Technology Assessmentnationwide survey of consumers in 1978 to determine their attitude about open-date information, usefulness and understanding of dates, and preference amongdates. The survey itself consisted of a questionnaire sent to a statisticallyselected sample of 3,000 consumers. *

ATTITUDES TOWARD OPEN DATINGAccording to the survey, almost all shop-

pers (96 percent) were concerned about get-ting the freshest food products possible.About 1 in 10 (11 percent) felt that a lot offood they buy from grocery stores is spoiled.

Although the consumers were concernedabout food freshness, their awareness ofopen dates varied considerably. The datesthemselves—their presence and form—var-ied by both product and by store.

Nearly all the shoppers (96 percent) wereaware of dates on milk. At least half noticeddates on other perishable products such asbread, eggs, ground beef, and round steak.

On a few semiperishable items such ascheese, luncheon meats, and cereal, a majori-ty of shoppers also noticed dates. However,

*OTA commissioned this survey, recognizing thatother surveys have been completed on this subject. TheOTA survey provides more detailed information on con-sumer preference and is more recent than the othersurveys. This survey is available on request.

for most other semiperishable items, only afew noticed the date.

Only about 12 to 14 percent of the shopperssaid they were aware of dates on nonper-ishable or long shelf-life food items such ascanned soup and canned vegetables, but thisis not too surprising since a smaller propor-tion of these products are open dated, com-pared with perishable products.

Eighty percent of the consumers surveyedconsidered open dates to be useful. Thisfigure compares with 67 percent in a 1973U.S. Department of Agriculture (USDA) studyon open dating and 90 percent in a similarstudy by USDA in 1976. Thus, open dates areconsidered by many to be useful in food shop-ping.

The OTA survey found that 62 percent ofthe consumers sort through items with anopen date to find the freshest product. Thiscompares with a 61-percent response to asimilar question in the 1976 USDA study.Therefore, retailers selling foods with open

13

14 . Open Shelf-Life Dating of Food

dates have an incentive to keep tight controlover their inventory if they want to avoid con-sumer culling.

Shoppers in the OTA survey were asked torank the following four different types of in-formation that may be found on food labels:1) open date, 2) recipes and cooking instruc-tions, 3) list of ingredients, and 4) nutritionalinformation (table 2). They were asked to do

this for several perishable and long shelf-lifefood items.

The survey found that the open date is themost important piece of information on thepackage label for fresh meat and frozen vege-tables and is second in importance to the listof ingredients on a canned soup label. Thus,among the various types of information on alabel, open dates are considered useful forboth perishable and long shelf-life foods.

Table 2.—Consumer Usefulness of Information on Food Packages(percentage of respondents)

—.

Freshness date . . . . . . . . . . . . . . . . . . . . . . . .Recipes and cooking instructions . . . . . . . . . . . . . .List of ingredients . . . . . . . . . . . . . . . . . . . . . . . . . . .Nutritional information . . . . . . . . . . . . . . . . . . . . . . .

a Less th-an”O 5—percent

— —. ————— ——.— ——

Frozenvegetables

50 -

221910

Cannedsoup

‘ -2 4194316 i---

Freshmeat

9 1-

243

Frozenvegetables

7472222.

Cannedsoup

29 -

451015

Fresh - -

meat—(a)543014

Since different types of open dates withdifferent meanings appear on various foodproducts, consumer understanding is a keyfactor. Therefore, the survey asked the con-sumers to identify the correct type of dateon milk, breakfast cereal, and ground beef(table 3).

The results were mixed. Nearly three-fourths of the shoppers knew that the date onmilk is a sell-by date. However, only one infour identified the date on breakfast cereal

as a use-by date; over one-third thought itwas a sell-by date. For ground beef, only one-third knew the date was a pack date, whilealmost another third thought it was a sell-bydate.

Therefore, aside from milk, it seems thereis considerable confusion over the meaning ofspecific open dates. The illustrations of vari-ous products on pages 16 & 17, with datinghighlighted, give visual evidence to the confu-sion of consumer understanding.

Table 3.—Consumer Understanding of Freshness Dates(percentage of respondents)

— -. —- Breakfast Ground ‘-

Milk cereal beefWhen it was packaged. . . . . . . . . . . . . . . . . . .

-—9 8 34“

Last day it should be sold . . . . . . . . . . . . . . . . . . 74 35 31Last day it should be used or eaten . . . . . . . . . . 15 26 9Have never not iced a date on a

package of this product. . . . . . . . . . . . . . . . . . 2 31 26

NOTE Percentages In boldface Indicate correct answers.-

Chapter II—Consumer Perspective Open Dating ● 15

PREFERENCE AMONG OPEN DATESWith different types of dates now in use, The most preferred form of dating was a

consumer preferences can be useful in deter- combination date rather than a single date. Inmining open-dating policy. The OTA survey, fact, almost two out of three (64 percent) saidtherefore, asked consumers to express their they would like to see two dates, either sell-bypreferences for different types of dates or and use-by or pack and use-by. (Consumercombinations of dates for various food items. representatives on the OTA panel also pre-Some consistent patterns appeared, as shown ferred combination dates.)in table 4.

Table 4.—Consumer Preferences for Open Dates(percentage of respondents)

Preferences among single dates and combinations

BothBothOnlyOnlyOnlyBoth

sell-by and use-by date . . . . . . . . . . ., . . . . . . . . 37 25pack and use-by date. . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 37use-by date. . . . . . . , . . . . 16 42sell-by date. . . . . . . . . . . . . . . . . . . . 9 60pack date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 75sell-by and pack date. . . . . . . . . . . . . . . . . . . . . . 5 59

Preferences among single dates for selected foods

Last Last – ‘ - Wouldday day Date not use

used sold packaged datePerishable products

Milk . . . . . . . . . . . . . . . . . . . 43 37 18 (b)Ground beef : : : : : : : : . . . . . . . . . . . . . . . . . . . 39 24 33 1Round steak . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 23 32 1

Semi perishable and nonperishable productsCheese. . . . . . . . . . . . . . . 44 34 18 2Canned tuna fish . . . . . . . . . . . . . . . . . . . 43 21 20 8Frozen vegetables ., . . . . . . . . . . . . . . . . . . 43 24 23 4Flour . . . . . . . . . . . . . . . . . . . . . . . 35 26 24 11Cake mix . . . . . . . ..., . . . . . . . . . . . . . . 34 25 22 8Jelly, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 18 18 17-. —- —-

Preferences among combination dates for selected foods

Perishable productsMilkGround beef ::: :::::::::::::: :::::.Round steak . . . . . . . . . . . . . . . . . . . . .

Semiperishable and nonperishable productsCheese. . . . . . . . . . . . . . . . . . . . . . . . . .

Sel l -by - -and

use-by

. 46

. . . 3939

s. 40

—.Packand

use-by

283333

30

‘-Sell-by - ‘Only -

and onepack date —

8 21Frozen vegetables . . . . . . . . . . . . . . . . . . . . . . 35 33 8 21Canned tuna fish . . . . . . . . . . . . . . . . . . . . . 31 32 8 22Cake mix . . . . . . . . . . . . . 27 29 8 29Flour . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 30 8 29Jelly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 23 7 31

aRanked Iower than third most ImportantbLessthan05Dercent

Seldom/never

purchase

147

1773

1117

Nodate

12

13666

16

16 . Open Shelf-Life Dating of Food

Dating Techniques of Various Food ProductsWhat Do They Actually Mean?

7

Remains Fresh l-WeekAfter Date Shown

Sell By

Buy Before 9 Best When Purchased By

Chapter II—Consumer Perspective Open Dating ● 17

“,‘

7

Best When Purchased By Sell By

18 . Open Shelf-Life Dating of Food

This leaning towards more than one dateindicates that consumers want as much in-formation as possible on product freshness.However, a significant minority (19 to 31 per-cent, depending on the specific food product)desired only one date.

If just one date were to appear on foodpackages, the use-by or best-if-used-by datewas the most preferred. This was true re-gardless of the perishability or shelf stabilityof the product.

Second choice to the use-by/best-if-used-bydate is the date currently placed on specificproducts. For example, most respondentspreferred the sell-by date to the pack date formilk, but just the opposite for ground beef andround steak.

Among combination dates, a sell-by/use-bydate was preferred for the three perishable

products and for two out of six semiperish-able and nonperishable products. The pack/use-by combination was the second most pre-ferred, and very few respondents preferredthe sell-by/pack combination.

Preliminary results of nationwide hearingsin 1978 by the Food and Drug Administration(FDA), USDA, and the Federal Trade Commis-sion shed further light on the issue of con-sumer preference in open dating. For thoseconsumers requesting a combination of dates,a pack/use-by date was favored for long shelf-life foods and a pack/sell-by or pack/use-bydate for perishables.

In conjunction with the above hearings,FDA commissioned a food-labeling survey inlate-1978. Summary results of that survey onopen dating are very consistent with the find-ings of the OTA survey.

DIFFERENCES AMONG SUBGROUPS OF SHOPPERSA number of demographic variables were ences appeared. For example, in high-income,

examined to determine if certain subgroups high-education, and large households, slightlywithin a population might show different at- more respondents felt open dates were use-titudes and behaviors with respect to open ful. Generally, though, demographic differ-dating of foods. Race/nationality, education, ences were not impressive. At any rate, suchage, income, family size, and religion were ex- differences do not seem crucial for establish-plored. ing an open shelf-life dating policy because in

Not surprisingly, in a large number of com- all groups the majority of respondents indi-

parisons across many items, some differ- cated that open dates were useful.

Chapter Ill

Benefits of Open Dating

As soon as harvested or slaughtered, most foods begin to deteriorate inquality. Some exceptions are fruits picked prior to ripening, such as bananas,and red meats and seasoned prepared foods, which first improve in sensoryquality before they deteriorate. Subsequent processing is done to slow down therate of deterioration and thus increase shelf life, thereby preventing waste.

The type of process used to preserve food largely determines the shelf life ofa product (e.g., canning gives a longer shelf life than refrigeration). In addition,environmental conditions can also directly affect food quality and speed up dete-rioration. Conditions such as high temperature, high humidity, light, and contactwith air (oxygen] all speed up this quality loss.

However, open dating in itself only sets the time of shelf life of foods—by ne-cessity ignoring the changing environmental factors by assuming the food is heldunder certain average conditions. If the date is based on these average storageconditions, the closer to the date (except for a pack date), the lower is the qual-ity.

Ideally, dating information should take into account the environmental fac-tors as a function of time. Although current technology is unable to do this,technology is being developed that will measure the influence of both time/tem-perature fluctuations on quality deterioration. Currently, a device can be at-tached to a food package that can measure the reaction to a specified time/tem-perature relationship or exposure to some temperature above a set limit. Thedevice must be designed to respond to temperature change in the same way asthe food product.

Studies on the reliability of these devices indicate two major problems:1) they become unreliable if exposed to high temperature prior to activation, and2) in many cases, their responses do not match manufacturers’ specifications.Although these devices have been modified since the aforementioned studieswere published, the major problem is still to develop an indicator that exactlymatches the sensitivity of a particular food to a change in temperature and/orother environmental factors. (For more information, see appendix C).

Therefore, with the gap in technology, the focus of this analysis is by neces-sity one-dimensional (open shelf-life dating) for a multidimensional problem offood-quality preservation.

Despite the limitations just outlined for open dating, many benefits are at-tributed to it. This chapter identifies and analyzes these potential areas, includ-ing food quality, nutrition, food safety, inventory control, and education.

19

20 ● Open She/f-Life Dating of Food

FOOD QUALITYWhether open dating benefi ts product

quality is of primary importance, given thefact that most food deteriorates with age.There are no published studies that show thatopen dating leads to the availability of higherquality foods.

An open date may not provide an assur-ance of high quality, since storage conditionsare critical to the quality of all foods and canbe highly variable. For example, if semiper-ishable and long shelf-life foods are tempera-ture-abused and are stored long enough, a de-cline in quality may be detected. A food witha more recent date that has been mishandledwill be of substantially lower quality than anolder dated food that has been stored underideal conditions.

In order to achieve high quality at point ofpurchase, then, the food must be of high qual-ity initially and must be handled under prop-er storage and distribution conditions. If bothof these criteria are not met, the date on thepackage (unless it is a pack date) could bemeaningless as well as misleading. Also, stor-age conditions after purchase could greatlyaffect the shelf life of the product.

Nevertheless, today’s consumers believean open date assures “acceptable” quality;such assurance is their primary reason forwanting an open date. However, in actualfact, a situation may evolve in which con-sumers believe that a date will be helpful tothem in terms of “better” quality when thestate of the technological capabilities may besuch that the benefits will be considerablyless than what is expected.

Even foods produced under the same condi-tions at a single location may undergo manydifferent time/temperature/humidity changeswhen they are distributed around the coun-try. Thus, an open date based on average cli-matic conditions may be an adequate qualitymeasure for some northern parts of the coun-try where temperatures are lower, but inade-quate if the product were held under hightemperature/humidity changes when distrib-uted around the country. It is possible that re-quiring an open date could improve the con-trol over foods during distribution to the pointthat the date would be an assurance of highquality.

In an in-store U.S. Department of Agricul-ture (USDA) experiment where open datingwas introduced, the incidence of consumercomplaints on food items most often citedpreviously as spoiled or stale was reduced by50 percent. Store losses in dollar values andpackage rehandling also were reduced.

Attributing these results to open datingwas questioned by those reporting the studyfindings. The reason was that the studyshowed a reduction in complaints about spoil-age for both open-dated and non-open-datedfood in the same store. Thus, some of the im-provement may have been because of in-creased confidence in the freshness of allfood sold in the store (to which open datingcould have contributed), rather than changesin the food itself—i.e., less spoilage. l

‘Food Dating: Shoppers Reactions and The Impact onRetail Foodstores, Market Research Report No. 984(Washington, D, C,: U.S. Department of Agriculture,1973).

NUTRITIONOpen dating could be of some value if used time of the sale of the food. In order to set the

with nutrition labeling. The nutrition label nutr i t ional levels , the manufacturer mayalready has a time factor built into it because have made a judgment about the length ofthe values on the label are required to be time and environmental conditions involvedwithin established statistical limits at the in the distribution of the food and how these

Chapter Ill—Benefits of Open Dating . 21

conditions would affect nutrient loss of the Thus, as previously discussed for quality,most unstable nutrients, such as vitamin C. an open date could be used to ensure im-However, as with quality, improper storage proved handling conditions that could resultconditions could result in greater nutritional in less nutrient loss. But whether this wouldlosses than predicted under average condi- improve the nutritional status of Americanstions. is questionable.

FOOD SAFETY

Open dating has little or no benefit in termsof improved microbiological safety of foods.For foods in general, microbiological safetyhazards are a result of processing failures,contamination after processing, and abuse instorage and handling. These factors are allindependent of the age of the product andhave little relationship to an open date, Infact, an open sell-by or use-by date couldhave an adverse effect on food safety if con-

INVENTORYAt the processor level, adequate inventory

control is currently provided by the codeddates now being used on food packages. Dis-tribution centers of manufacturers and cen-tral warehouses of supermarket chains canalso use the code for proper stock rotation,although they do not always do so.

Consumers, however, feel that inventorycontrol via coded dates really breaks down atthe end of the distribution chain, The localstore managers and supermarket stock clerksmay or may not use the coded dates. Becausethey are in code, consumers cannot use them

sumers took it to be an assurance of foodsafety. For example, “Well, it looks, smells,and feels bad, but the date says it’s good foranother month, so I’ll use it. ” Poor manufac-turing processes can still exist with an open-dating system, and consumers could be givena false sense of security. A date with specificstorage information (e.g., “keep cool afteropening”) could, however, reduce hazards.

CONTROL

to decode each product. Open dating couldobviously tighten inventory control by boththe retailer and the consumer.

USDA found that in their in-store experi-ment, open dates encouraged better food-han-dling practices by making store personnelaware of the need for rotation. Confusionamong clerks about when to rotate or removeproducts was reduced, and closer attentionwas given to expediting sale of products nearthe end of their shelf life so they did not haveto be discarded.2

2Ibid.

EDUCATIONAn important benefit of open dating could tion conditions and studying how specific

be the education of the food manufacturer foods deteriorate. Open dating in the long runand the consumer. Much of the consumer’s would increase the body of knowledge abouteducation about a particular product usually the quality and chemistry of food products.comes from the food industry in the form of The food industry as a whole should be cer-advertising and package information. Thus, tain that the information given in an openthe research forced on the manufacturer in date is not misunderstood in terms of quality,order to establish an open date is a form of safety, and nutritional assurance.self-education in terms of analyzing distribu-

Chapter IV

Alternative Open-DatingTechniques

Converting codes to open dates offers many possibilities. The date could beany of four possible dates, or a combination of dates, and there is a variety ofways the date could be presented.

Basically, the types of open dates are:

1. date of pack or manufacture,2. pull date or sell-by date,3. best-if-used-by date,4. expiration date or use-by date, or5. combination of two of the above.

The meaning of these dates is not necessarily obvious. The pack date refersto the day, month, and year the food product was processed or packed for retailsale. The pull or sell-by date refers to the last date the food product should besold in order to allow the consumer a reasonable length of time in which to use it.The best-if-used-by date is the date after which the food is no longer at its mostacceptable level of quality. The use-by date is the date after which the food is nolonger at an acceptable level of quality.* The terms “pack,” “sell by,” and“best-if-used-by” will designate these alternative open dates, respectively.

This section is a general discussion ofopen-dating methods. Appendix A offers a de-tailed discussion by major food category ofthe advantages and disadvantages of eachmethod.

*Food scientists make this distinction between use-byand best-if-used-by dates. Consumers do not necessari-IV see the difference. Many think either of these datesindicate the date at which food is no longer at an ac-ceptable level of quality.

Pack Date

A pack date is the only date that could beput into effect in the near future if an opendate were mandated for all food products.Compared with the other dates, it is also theleast expensive because it requires only his-toric data—i.e., the time of the event is knownwithout research or estimation. However, itmay not be the best date for all food products.

23

24 ● Open She/f-Life Dating of Food

The pack date, as defined above, has threeproblems:

1.

2.

3.

the condition and length of time the prod-uct was held before being packaged isnot considered,some products such as fresh meat can bereconditioned and repackaged for sale,andages of separate components in a multi-component food such as a dried soup mixcould vary.

In regard to the first point, some consumersfeel that manufacturers store food in bulk foran unreasonably long time before putting it inthe final package. Manufacturers, on theother hand, feel they should be allowed tohold commodities for as long as is economical-ly expedient if they use ideal conditions ofstorage that minimize possible quality loss.Examples of kinds of foods that would fall inthis category are foods frozen in bulk beforebeing packaged, such as concentrated orangejuice, some vegetables, concentrated milk tobe used in ice cream, and flour.

For most perishable foods, a pack datewould be of minimal value to the consumer ifused by itself. For example, with milk anddairy products, it would only indicate thedate the milk was processed or packaged. Itwould not give the consumer any informationas to quality or how long the products shouldremain at a level of acceptable quality. Forprecut/prepackaged meats, poultry, and fish,the use of a pack date would give the consum-er some information as to general productquality but may also give a false sense ofquality assurance if the product is repack-aged under different conditions to lengthenshelf life or if held in frozen storage for someperiod of time before being offered for retailsale.

For shelf-stable engineered or multicom-ponent foods, the shelf life is determined bythe age and quality of the various compo-nents—which could vary widely. A pack datealone would give too little information for theconsumer to make any estimate of quality orshelf life. Examples of these multicomponent

foods include dried soup mixes, cake mixes,canned mixed fruits and vegetables, helper-type meals, and meat substitutes.

Foods for which a pack date seems reason-able are prepackaged fresh fruits and vegeta-bles. These food products are not processedto lengthen shelf life and cannot be frozen forany part of their storage life without seriousalteration of product quality. Thus, the use ofan open pack date would actually convey toconsumers freshness information (assumingimmediate packing after harvest).

The use of a sell-by or best-if-used-by datefor prepackaged fresh fruits and vegetableswould require the retailer to estimate whenthe product would reach its peak of ripenessor begin to exhibit significant and detectableloss of quality. Because fruits and vegetablesof different varieties, and even within thesame variety, may mature at different ratesdepending on the size, storage conditions, andother factors, such a date could not be estab-lished with a reasonable degree of accuracy.

Sell-by and Best-if-Used-by Dates

Information for scientifically determiningthese dates does not always exist, as for thepack date, so processors and manufacturersmust frequently estimate or create a date. Inorder to set a valid sell-by or best-if-used-bydate, the following information must be ob-tained:

1. a measure of some initial relevant quali-ty factor that can be used to estimate adecrease in consumer acceptance,

2. a reliable method to measure that quali-ty factor on a statistically sound basis,

3. the distribution system times and condi-tions,

4. the average time the product is held inthe consumer’s home before use, and

5. the amount of quality loss allowed be-fore the product is considered unaccept-able for sale at full price or for use.

A sell-by date could be set if the averagetime the product is in the distribution system

Chapter IV—Alternative Open-Dating Techniques ● 25

is known, but it must also assume someknowledge of how long it will take the aver-age consumer to handle, store, and use thefood in the home under conditions that will re-tain good quality. Thus, storage and distribu-tion information is necessary to establish anydate other than a pack date. If this knowledgeis not available, the date is not meaningfuland might be misleading.

There are regional problems involved withuse of open dates for products such as driedsnack foods, pasta, and breakfast cerealsthat are distributed nationwide and are sub-ject to extremes in temperature and humidityconditions, For example, for any food wheregain or loss of moisture is related to quality(e.g., loss of crispness in potato chips), a datefor reaching the critical moisture contentcould be established for any given distribu-tion area, but it could be costly to do.

If, on the other hand, the end destination isunknown, the date could be set for the worstpossible conditions. The problem with this ap-proach would be that a large percentage ofthe food going to areas of the country withmoderate conditions would still be good whenmarked out of date. For example, if the opendate must be set to allow for moisture gain ina high humidity area such as Mississippi, na-tional distributors would either have to pro-tect all packages against extreme conditionsand charge consumers for such steps, or suf-fer product losses. These considerationscould result in some companies withdrawingfrom national distribution.

The sell-by date is usually used in conjunc-tion with foods that have a short shelf lifeafter the date of sale, if properly handled.Milk and dairy products, such as yogurt, arelabeled in this way, and, in fact, some pack-ages may give further information as to daysof shelf life beyond the selling date.

The sell-by date is the single most usefuldate for wholesalers and retailers. Its advan-tage is that it is unambiguous relative to thebest-if-used-by date. Both wholesalers and re-tailers know the normal amount of time anygiven product requires to move through their

segment of the marketing system. This knowl-edge in combination with a recommendedsell-by date gives the wholesalers and retail-ers the means to assure freshness through in-ventory control.

OTA’s consumer survey found that the sell-by date is not the open date that consumersprefer for food products, however. In both theperishable, semiperishable, and long shelf-life food categories, consumers preferred thebest-if-used-by date to the sell-by date or packdate. Except for prepackaged fresh meat, thesell-by date says little or nothing about whenfoods should be used or when the quality maybe detectably worse.

A best-if-used-by date, on the other hand,does not permit wholesalers and retailers thesame ease or potential accuracy in inventorymanagement that a sell-by date allows. Thesedates require wholesalers and retailers to in-dividually and subjectively determine allow-ance for home storage time on each individ-ual product in order to calculate a sell-bydate—i.e., the date they need for manage-ment purposes.

For processors, a best-if-used-by date ismore useful than a sell-by or use-by date.They feel it is the most informative to the con-sumer and, with the exception of the packdate, the least arbitrary and restrictive. Tothe processors, the sell-by and use-by datesimply that at some moment in time a dramaticchange will take place in the quality and suit-ability of the product. That is, before a givendate, the product is acceptable; afterward, itis not and must be discarded. This, of course,is not true, but processors fear that consum-ers might interpret it this way. Therefore,they prefer the best-if-used-by date, feeling itcarries the connotation that there is a slowbut continuous loss of quality, and for thegreatest satisfaction to the consumer, thefood should be consumed by that date.

The best-if-used-by date is being examinedby Codex Alimentarius, the international or-ganization for food labeling standards. Thesestandards say that for all products the firstdate that should be looked at is the date of

49-394 0 - 79 - 3

26 . Open Shelf-Life Dating of Food

minimum durability, which translates to abest-if-used-by date.

A modification of the best-if-used-by date isthe best-if-used-within date. In this instance,phraseology such as “best if used within 30days of June 1“ becomes a compromise be-tween what retailers and consumers desirefrom an open date. For example, the best-if-used-by date indicates that the productshould be used on or before the date speci-fied. “Best-if-used-within” indicates the prod-uct should be used within 30 days of June 1.The difference between the two dates is thatthe former gives only a use-by date. The lattergives both a sell-by date and use-by date. Inthis example, the sell-by date is June 1. Theuse-by date is 30 days after, or July 1. Thesephrases offer an unambiguous sell-by datefor the retailer, while at the same time givingconsumers a use-by date.

TO Remain in Grade Use- (Sell-)by Date

An alternative to a use- (sell-) by date or,more specifically, instead of “best-if-used-by” may be a term that would indicate howlong a food may be held and yet remain at aquality level practically indistinguishablefrom that quality inherent in the original packdate. This may be accomplished by using aterm such as “to remain in grade, use (sell)by. ” For example, if a product is found to beof top quality and is graded and labeled“grade A,” “prime,” or “fancy,” the opendate would indicate how long it may be ex-pected to remain at top quality. If it is labeled“grade B“ or “choice,” the open date wouldindicate how long the unit is expected to re-main at the declared second quality level, etc.

Although such terminology would be lim-ited to products that have precisely definedand generally recognized and accepted quali-ty grades and standards, for those commodi-ties where it could be used, it would have theadvantage of specifying the quality levels ex-pected to be retained—not just a vague“best,” or “acceptable.” A corollary benefit

would be that if the date should be exceededbefore use (or sale), there need not be the im-plication that it is unsafe and should not beused.

Integrating open dating with grade labelinghas the potential of simultaneously strength-ening and appreciably reducing costs of im-plementing both. It may even be argued thatgrade labeling must include open dating,since “nothing is forever. ” This may be thesolution to the difficult problem of limiting thelife of a grade after it is posted on a label. Forexample, a carton of eggs labeled “grade A“could be assumed to remain “grade A“ for-ever unless the grade declaration would in-clude an open date. This benefit need not belimited to perishables. In-grade life of rela-tively stable foods, such as canned vegeta-bles, can vary substantially not only amongcommodities but even within commodities.

A disadvantage of an integrated system isthat it would work only for those productswhere the grade is equated with freshness-quality attributes. Products such as b e e f ,pork, lamb, and poultry would therefore beexcluded, since the grade is based more oncompositional/conformation characteristics.

Another disadvantage is that many con-sumers have little knowledge of what gradesmean, So, equating an open date with a gradewould result in consumer confusion.

Combination Dates

As reported in chapter II, the OTA consum-er survey found that the most preferred dateswere combination dates. Specifically, thecombination of sell-by and use-by dates wasmost preferred, followed by a pack and use-by combinat ion. Obviously, combinat iondates supply the most information to con-sumers.

Such a system is visualized as “retailer sellby” and “consumer use by” on the sameproduct— similar to the best-if-used-withindate, which is in itself a combination date. Onsome products, a combination date could give

Chapter IV—Alternative Open-Dating Techniques ● 27

the optimum information to both the whole-saler/retailer and the consumer. From a coststandpoint, combination dates would be morecostly than a single date, In addition, multipledates would take more label space, whichfrom industry’s viewpoint could be used forother information.

A key issue in using combination dates iswhether they will result in consumer confu-sion or education. For example, it can beargued that if only one type of open date wereused on all products, potential consumer un-derstanding could be at a maximum. Con-versely, if consumers were confronted withseveral different types of open dates, confu-sion could result.

If one accepts this “inverse” relationship,one could argue from a consumer viewpointthat a single type of open date should be usedon all products, regardless of other factors,such as product deterioration. The alter-

native viewpoint is that even if this “inverse”relationship does exist, efforts could be madeto educate consumers on the use of differenttypes of dates.

Results from the OTA consumer surveylend support to the latter viewpoint in thatthey tend to refute such an inverse relation-ship. The results suggest that a majority ofconsumers think that combination dateswould be beneficial on at least some prod-ucts. Presumably, if the consumers thoughtdifferent kinds of dates for different productswould be confusing, they would not feel thatcombination dates would be useful.

The benefit of adopting a standardizedopen date for all products is simplicity.Wholesalers, retailers, and consumers wouldknow or eventually learn how to use and dealwith that s tandardized date. However, astandardized date may not be the optimumone for certain products.

IMPLEMENTATION

Storage Instructions

Based on the OTA survey and other sur-veys, it is apparent that consumers feel thatas much information as possible should be in-cluded on the food package, including storageinstructions as well as an open date.

As discussed earlier, the shelf life of food isbased on some definite conditions of storage.If these differ significantly from those antici-pated, the shelf life of the food will vary, be-ing shorter if the actual conditions turn out tobe more unfavorable, and being longer if theyshould be more ideal. Thus storage instruc-tions, if observed, would enhance the useful-ness of open dates, but they raise the increas-ingly critical problem of space on the label.

Processors in the OTA working group feelthat the presently used instructions found onsome food products such as “keep refriger-ated, “ “keep in a cool, dry place, ” and “keepfrozen until used” are adequate. In addition,

available space on the package is not ade-quate for elaborate storage instructions, andtoo many other regulations relating to re-quired information and size of print usedwould be affected. There is little doubt thatconsumer education about proper storage in-structions is an important—and necessary—part of open dating. Such education might beaccomplished through use of television, pam-phlets, or posters, however, rather than thepackage label.

Type of Date Marking

With respect to the actual date itself, con-sumers surveyed and consumer representa-tives on the OTA working group wanted themonth, day, and year. 1 The most preferred

‘Food Do tin~: Shoppers Reactions and The Impact onRetail Foods tores, Market Research Report No. 984(Washington, D. C.: U.S. Department of Agriculture,1973).

28 . Open Shelf-Life Dating of Food

form was “8 May 78” rather than “May 8,‘78, ” “ 5/8/78, ” or “8/5/78” because of “possi-ble confusion. ” (Such a form also takes upless space than “May 8, ‘78.”)

Preliminary results from the 1978 con-sumer hearings held by the Food and DrugAdministration (FDA), the U.S. Department ofAgriculture (USDA), and the Federal TradeCommission (FTC) support these findings. Infact, indications are that the vast majorityprefer an alphanumeric date—"8 May 78” or“May 8, ’78” —to a da te in a l l numer -als—"5/8/78" or “8/5/78.”

Processors, wholesalers, and re ta i l e r shave no significant problems with these pref-erences. However, the possible exclusion ofthe year could be made for highly perishableproducts such as fresh meat and bakery prod-ucts, and omission of day of the month forlong shelf-life foods. This is a common featurefound in many countries that open date theirfood products.

As far as actual implementation goes, athree-letter designation could be used for themonth: JAN, FEB, MAR, APR, MAY, JUN, JUL,AUG, SEP, OCT, NOV, DEC. However, thefact that these designations require a com-bination of 20 letters, in addition to numbers,complicates high-speed printing operations.Still, too much confusion could result fromusing numbers alone. For instance, for thefirst 12 days of any month, the day of themonth could also be the number of the monthitself.

For some food packages, there are techno-logical problems in printing dates. Frozen

food packages— especially cardboard—pre-sent a challenge because cardboard tends t oreturn to its initial shape when a date is em-bossed on it; the wax loses its effectiveness asa humidity barrier if the date is cut into it;and inks do not mark well on wax.

The type of package employed should notinfluence the specific information providedby the date, but it could determine the par-ticular technique by which the date and asso-ciated information are applied on the contain-er. For example, it may be impractical anddangerous to emboss a retortable pouch, andsome type of printing or sticker label mightneed to be designed. Also, it is generallyacknowledged that open-date printing wouldhave to be done at the point of packaging onpreprinted labels with space left for an opendate. It would be difficult to make labels withthe proper information ahead of time becauseof the logistics of processing.

Despite the technological problems, themajor impact on food manufacturers of ap-plying open dates would be that more pack-age space would be taken away from themwhich must be used for the label. This couldlead to a decrease in the availability of smallsingle-serving packages that may not have theadded space required.

The impact on other groups would be theincreased need for education. Precision andbrevity of terms and easily recognized datesare important for the consumer to under-stand the date itself as well as to help thoseinvolved in the distribution and marketingsystem.

EXEMPTIONS

There are specific food products that tainer or wrapping prior to sale; c) salt; andshould be exempted from open dating. These d) crystallized refined sugar.are: a) bulk fresh fruits and vegetables—those products sold unpackaged at producecounters; b) fresh meats, poultry, and fish The principalthat are cut and prepared in the retail store, fresh fruits andare not frozen at any t ime during their poultry, and fishstorage life, and are not packaged in any con- quality of these

reason for exempting bulkvegetables and fresh meat,from open dating is that theproducts is normally deter-

Chapter IV—Alternative Open-Dating Techniques “ 29

mined by sight, touch, and smell before pur-chase is made. Because these products aresubject to varying rates and types of deter-ioration, including physical destruction as afunction of consumer handling, it would notbe possible to arrive at a meaningful shelf-lifedate for each product. There would also beproblems in physically placing a date on in-dividual items, and the cost of such a pro-gram would be prohibitive.

A date of any kind is not meaningful for

certain foods such as salt and crystallizedrefined sugar, which when held under properconditions are good for 10 to 20 years. Theseproducts however, do not have an infiniteshelf life because if held at high humidity,they can cake. From a practical viewpoint,though, there are very few si tuat ions inwhich food is actually stored 10 to 20 years.These foods could be said to have a shelf lifeso long that it is not a relevant factor in theirpurchase or use.

Chapter V

Establishing Open Dates

In order to establish a fairly accurate open date (except a pack date) for aparticular food, one needs to know how that food deteriorates. All foods begin todeteriorate at some speed (rate) as soon as they are packaged and continue todeteriorate until they may no longer be acceptable. Some foods deteriorate rela-tively quickly and others very slowly.

Food shelf life is not totally dependent on time but also on environmentalconditions such as temperature, humidity, light, and oxygen. The prime fac-tors—temperature and humidity-may increase deterioration as they rise, orslow the process as they become lower. However, their impact depends on howwidely they vary and on the product itself. Also, as the food deteriorates, theprocess may accelerate because of its own momentum.

Examples of possible modes of deterioration, the most critical environmen-tal factors; and the most feasible open date for some perishable, semiperishable,and long shelf-life foods are listed in table 5. The primary mode, if known fornormal conditions, is in bold italic type. How foods deteriorate may change radi-cally with sterilization procedures, packaging, condition of raw material, etc.

As can be seen in table 5, in no case is safety a concern in any of the normaldeteriorations of food. In cases of certain meats or poultry, foodborne infectionsthat might be disseminated by the product could make the question of safetymore relevant than for other foods. However, for most food, other factors thatresult in an inedible product occur before a point of health hazard is reached ifthe product has been properly processed, packaged, and not abused or contami-nated.

Most perishable and semiperishable foodsdegradate mainly on sensory quality criteria.For example, fresh meat degrades mainly bybacterial activity and oxidation that cause anoff-flavor development and loss of color. Thisis readily recognizable by consumers.

In contrast, many long shelf-life foods deg-radate mainly on nutritional criteria. For ex-ample, frozen fruits and vegetables are con-sumed as a major dietary source of vitaminsand minerals. In some cases, vitamin content

may fall below some accepted standard be-fore sensory quality becomes inadequate. Inaddition, most long shelf-life foods are pack-aged so that it is impossible to examine thecontents. Consumers cannot recognize loss ofsensory quality until the product is unpack-aged after purchase. Open shelf-life dating is,therefore, as applicable to long shelf-lifefoods as it is to perishable and semiperish-able foods, particularly if these foods arestored in the distribution system or home fora fairly long period of time. Some type of dateis useful to ensure proper rotation and give

31

32 ● Open She/f-Life Dating of Food

Table 5.—Major Modes of Deterioration, Critical Environmental Factors, Shelf Life, andType of Open Dating by Food Product

—— — . —

Shelf lifeDate mostsuitable for Additionalproduct information —-Food product

Perishables factors (average)

Fluid milkand products

bacterial growth,oxidized flavor,hydrolytic rancidity

7-14 days atrefrigeratedtemperature

sell-by length of timeproduct can bestored at home

oxygen,temperature

Fresh bakeryproducts

staling, microbialgrowth, moistureloss causinghardening, oxidativerancidity

2 days (bread)7 days (cake)

sell-byoxygen,temperature,moisture

Fresh redmeat

bacterial activity,oxidation

3-4 days atrefrigeratedtemperature

pack orsell-by a

oxygen,temperature,light

Fresh poultry pathogen growth,microbial decay

2-7 days atrefrigeratedtemperature

sell-by a length of timeproduct can bestored in homeeither frozenor refrigerated

oxygen,temperature,light

Fresh fish bacterial growth temperature 14 days whenstored on ice(marine fish)

pack(catch date)a

Fresh fruits microbial decay,and vegetables nutrient loss,

wilting, bruising

temperature,light, oxygen,relative humidity,soil & water,physical handling

(b) pack a

Semiperishables and perishables

Fried snack rancidity, loss offoods crispness

sell-by orbest-if-used-by

home storageinformation suchas “store in acool, dry place”

oxygen, light,temperature,moisture

4-6 weeks

Cheese rancidity, browning,lactose crystalliza-tion

temperature processedcheese4-24 months;natural cheese4-12 months

1-4 months

best-if-used-by

Ice cream sell-by orbest-if-used-by

recommendedhome storagetemperature

graininess caused bylactose crystallize.tion, loss of solubil-ization (caking),Iysine loss

Long shelf-life foods

Dehydrated browning, rancidity,foods loss of pigment,

loss of texture,loss of nutrients

fluctuatingtemperature(below freezing)

estimateof shelflife beyondsell-by date;store in cool,dry place

moisture,temperature,light,oxygen

dehydrated vege- sell-by ortables 3-15 best-if-months; dehy- used-bydrated meat 1-6months; driedfruit 1-24 months

Nonfat flavor deterioration,dry milk loss of solubilization

(caking), Iysine loss

moisture,temperature

12 months best-if-used-by

Chapter V—Establishing Open Dates ● 33

Table 5.— Major Modes of Deterioration, Critical Environmental Factors, Shelf Life, andType of Open Dating by Food Product—Continued

Food product

Breakfastcereals

Pasta

Frozenconcentratedjuices

Frozen fruitsand vegetables

Frozen meats,poultry, andfish

Frozenconveniencefoods

Cannedfruits andvegetables

Coffee

Mode of deteriorate ion(assuming anintact package)

rancidity, loss ofcrispness, vitaminloss, particlebreakage

texture changes,staling, vitaminand protein loss

loss of turbidityor cloudiness, yeastgrowth, loss ofvitamins, loss of coloror flavor

loss of nutrients; lossof texture, f/aver,color: and formationof package ice

rancidity, proteindenaturation, colorchange, desiccation

rancidity i n meatport ions, weepingand curdling ofsauces, loss offlavor, loss ofcolor

loss of flavor,texture, color,nutrients

rancidity, lossof flavor and odor

Criticalenvironmentalfactors

moisture,temperature,rough handling

too high or lowmoisture,temperature

temperature

temperature

temperature

oxygen,temperature

—D a t e - m o s t

Shelf life suitable for Additional(average) product information

6-18 months best-if- recommendedused-by storageor sell-by conditions

pasta with egg best-if-solids 9-36 used-bymonths; macaroniand spaghetti24-48 months

18-30 months sell-by orbest-if-used-by

6-24 months best-if-used-by

beef 6-12 months best-if-veal 4-14 months used-bypork 4-12 monthsfish 2-8 monthslamb 6-16 months

6-12 months best-if-used-by

temperature 12-36 months best-if-used-by

oxygen ground, roasted, best-if-vacuum-packed, used-by9 months;instant coffee18-36 months

Tea loss of flavor moisture 18 months best-if-absorption used-byof foreign odors

month of highquality left inhome storage

recommendedstorageconditions

recommendedstorageconditions

recommendedstorageconditions

aThls date applres only If the product IS packaged prior to sale If unpacked or sold In bulk prior to sale this product IS exempt from an open date-.

bDepend~ on the spec(f(c commodity Sweet corn has a shelf life of 4 to 8 days and apples range from 3 to 8 months at ProPer temperature For this sPeclf(c ‘n fo rma

!Ion see Theodore Labuza et al Open Shelf Dattng of Foods. Dept of Food Science and Nutrltlon Unlverslty of Minnesota report prepared for the Office of Technology Assessment 1978

NOTE When known the pr)mary mode of deterioration IS In bold (tal!c type

34 ● Open Shelf-Life Dating of Food

the consumer an index of when foods shouldbe used.

Since the mode of deterioration and criti-cal environmental factors determine the shelflife of a product, they should be considered inselecting the type of open date. In general, forperishable products, the most feasible date isthe pack or sell-by date. For example, almostall fresh red meat is packaged by the retailerwho deals directly with the public. The meatmay have been slaughtered from 1 day to 2weeks previously. Since carcasses of proper-ly handled beef are essentially sterile inter-nally, it is the packaging procedure that initi-ates color change and bacterial spoilage. Be-cause the shelf life of fresh meat is relativelyshort beyond the date of packaging, a packdate or sell-by date may be sufficient for con-sumer use and understanding.

A best-if-used-by date would also be usefulto the consumer for fresh meat and other per-ishable products. However, these productsare very sensitive to temperature changes,which can result in very rapid deterioration.

Thus, the potential for consumer abuse maybe too great for a best-if-used-by date to be apractical alternative.

In general, the most suitable date for longshelf-life foods is the best-if-used-by date. Forexample, with canned fruits and vegetables,the date of pack would be the easiest to imple-ment but would not tell the consumer any-thing about the shelf life of the product. Can-ners who pack seasonal crops would be in adifficult position because the date on the canswould seem old when the product is actuallystill well within the shelf life of the product.This would be especially true in years whenan overabundant crop would force the can-ner to sell some products the following year.

A sell-by date is not applicable to cans thatare often stored in the home for some longperiod of time after being sold. The best-if-used-by date could be useful to consumersbecause it would give an appreciation of theshelf life of the product if conditions of stor-age were known or uniform. (For a detaileddiscussion by product, see appendix A.)

ALTERNATIVE CRITERIAThe general criteria to establish a sell-by

or best-if-used-by date will depend on whatthe date is meant to imply. A sell-by dateshould mean that there is still high-quality lifeleft for some time period of home storageunder reasonable conditions. A best-if-used-by date further states this by projecting areasonable time period. It is not possible toset an exact end to shelf life (a definite use-bydate) for any food product.

Such criteria would have to be based onwhat degree of change caused by each of thedeteriorative reactions in table 5 would leadto a “significant” loss in high quality. Thiswould apply to rancidity, flavor loss, brown-ing, textural change, etc. Such tests for sen-sory quality (taste panels, preference tests,etc.), although well-developed and used inproduct testing, would be difficult to use in a

regulatory sense to determine whether a spe-cific food was in or out of compliance at a cer-tain date unless the regulators were trainedfor each product. What is needed in thissense is a chemical or physical index thatchanges in a similar manner to the sensorychanges.

Sensory Quality

Although more difficult to measure in cer-tain cases, sensory quality is the most impor-tant characteristic for consumers and proc-essors alike, and in some cases with foods oflong shelf life, this quality may also be an in-dicator of nutrient quality. This is not true forshorter shelf-life foods such as milk.

Chapter V—Establishing Open Dates ● 35

Manufacturers def ine their o w n q u a l i t ystandards through elaborate product devel-opment studies, many of which include sen-sory testing, when they put a brand name ona product with a best-if-used-by date. In thisway, they assume quality loss up to that pointis still acceptable enough that the consumerwill buy the product. If consumers buy theproduct and find it below their own qualitystandards, they will probably not buy theproduct again.

Consumer reaction, then, is the key to qual-ity standards, because Government regula-tory agencies would not have available theneeded methods to determine whether a givenfood that is still in date is out of compliancewith some quality standard. For example, ifan inspector picked up a can of soup and tookit back to the laboratory, he might not havethe scientific tests available which could de-termine with any degree of accuracy if thatsoup is of a designated quality and thereforeacceptable to the consumer.

Assuring compliance with sensory qualitymight be feasible if the sell-by or best-if-used-by date were coupled with official Govern-ment or widely accepted industry qualitygrades. Thus, instead of merely stating “use-by” or “best-if-used-by” when there is no de-fined “best” quality, the open date could bepreceded by a statement such as “to remainin grade, use by. ”

The addition of an open date to a gradedeclaration would automatically solve the ex-isting serious problem of unlimited guaranteeof a specified quality grade level from thetime the grade is marked on the container un-til its destruction. The more perishable theproduct, the more important would be thegrade/open-date combination, While cannedgreen beans could well remain in grade for ayear or longer provided the container is un-damaged and not exposed for long periods tohigh and/or fluctuating temperatures, freshgreen beans could go out of grade in just afew weeks, or even days,

Open dating, when coupled with qualitygrade levels , can be based on accurate,

rapid, and scientifically sound methods ofanalysis for some foods. However, opendating based on retention time within thegrade can be applied only to those few hun-dred items for which generally recognizedand approved grades already exist. Theseitems are those for which grade levels can bemeasured accurately and precisely.

Nutrient Loss

Another measure of shelf life could be theloss of a certain percentage of a criticalnutrient, such as vitamin C. This factor wouldbe much easier to measure than overall quali-ty, since it can be analyzed accurately andrapidly in the laboratory. The same would betrue for moisture gain or loss of a criticalvalue that would cause some textural change,such as loss of crispness of a potato chip.

However, many scientists favor a specificsensory quality criteria for each type of foodrather than a given percentage loss of anunstable or critical nutrient for all commod-ities. Nutrient content of even the same foodscan be quite variable, particularly the vita-min content of many raw agricultural com-modities, For example, two tomatoes pickedat the same time can vary significantly invitamin C content. More importantly, somefoods are naturally poor in some nutrients,are not eaten to provide those nutrients, andmay be of good quality even if they have lost acertain percentage of the nutrients. In otherwords, if a food only contains 1 percent of theU.S. recommended daily allowance of vitaminC, a 10-percent decrease in this low amountwould most likely have an insignificant effecton overall nutritional status of the consumer.

If nutrient loss is to be used as one index ofquality loss, foods would have to be examinedon a product-by-product basis. In essence,this has already been done for nutrition label-ing. However, to prove that a loss in nutrientsis of significance to overall quality of eachand every commodity would be difficult.

36 ● Open Shelf-Life Dating of Food

Perishability Time CategoriesSome States with open-dating require-

ments use perishability time categories to es-tablish an open date. The three general cate-gories are: perishable, semiperishable, andnonperishable. Time categories can be rele-vant for highly perishable foods that have aminimum of processing such as fresh meat ormilk. However, processing conditions andtypes of packaging can increase the shelf lifeof semiperishable and long shelf-life foods tothe point where such perishability time cate-gories are not meaningful unless continuouslymodified to reflect new circumstances. Forexample, semiperishable foods can be de-fined as those foods with a shelf life ofgreater than 7 days but less than 90. Underthis system, in general temperature and envi-ronmental condit ions, most potato chipswould be defined as semiperishable. How-ever, if they were packed in a foil pouchunder nitrogen with added antioxidants, thechips might last for up to 6 months and wouldnot fit the category.

Some States have met this problem by de-veloping a nonperishable or long shelf-life

food category that can be defined as foodswith a shelf life of greater than 6 months. Aspointed out earlier in this report, this is, infact, a scientific misnomer, for all foodsdecay at some rate by some means. Even inthe above example with potato chips, if thenew method of packaging gave an averageshelf life of 120 days but the product wasabused in distribution and held at high tem-peratures (38 0 C) for a few days, it could de-teriorate fast enough that it would no longermeet the criteria of nonperishability. There-fore, perishability terminology cannot be logi-cally backed-up scientifically since one cancontrol or change shelf life through varyingprocessing, packaging, and environmentalconditions.

Basing open dating on time categoriescould also be a hindrance to implementingnew technology. For example, better packag-ing can increase shelf life of potato chipsfrom 90 to 120 days, even in regions with highhumidity. However, this better packagingwould not be used if potato chips could not besold at full price after 90 days no matter whattheir quality may be.

SCIENTIFIC TESTS AND DATA NEEDED

To develop sell-by or best-if-used-by datesscientifically, each manufacturer would needto conduct shelf-stability studies on eachproduct and determine the point in time atwhich sensory quality falls below the point ofconsumer acceptance. This is very time-con-suming and difficult to determine unless thefood has a short life under constant normalenvironmental conditions.

Knowledge of temperature and humidityconditions encountered during distributionare necessary to set the sell-by or best-if-used-by dates. A manufacturer can deter-mine this in one of two ways. He can put aproduct out in the marketplace, pick upsamples at various times and places in themarketing channel, and test the quality of the

samples at regular time ntervals to establishthe appropriate date for the product. But forproducts with several years shelf life, such ascanned vegetables, these studies could takeas long as 3 to 4 years.

The other alternative for the manufactureris accelerated shelf-life tests (ASLT). Thesetests would be necessary for new-product de-velopment and could be advantageously usedfor existing products where shelf life undernormal marketplace conditions is very long.ASLT involves subjecting the product to twoor three given constant environmental condi-tions and measuring the rate of quality loss ateach condition. A mathematical formula canthen be established for the rate of deteriora-tion as a function of temperature and/or

Chapter V—Establishing Open Dates ● 37

humidity and used to predict the time neededto reach an unacceptable amount of changeduring distribution and storage.1

In a select sample of 50 food manufac-turers, OTA found that the scientific ap-proach described in this section and in thebackground report is frequently not utilizedexcept by major corporations with highlyqualified scientific personnel. The low use ofshelf-life testing results from lack of knowl-edge and, more importantly, lack of experi-ence in determining the shelf life of estab-lished foods as well as the costs involved.2

The major impact of developing scientificdata would fall on the food manufacturer. Asignificant amount of time and money must beused to establish a data base for each prod-uct because broad generalizations cannotsuffice, Because of the cost, most manufac-

‘Theodore Labuza et al., “Open Shelf-Life Dating ofFoods, ” Department of Food Science and Nutrition,University of Minnesota, report prepared for the Officeof Technology Assessment, 1978.

‘Ibid.

turers would probably consider these data tobe of a proprietary nature and would notrelease it to the Federal Government or thescientific literature. Another impact wouldbe that the wholesalers, distributors, foodbrokers, and retailers would need to supplyinformation on each product’s history, as re-gards time, temperature, and humidity condi-tions encountered along the way to final sale.

Since shelf-life testing is product-specific,it would be very expensive for the FederalGovernment to undertake these types of testsfor all food products. The Government could,however:

1.

2.

Support research into modeling shelf-lifestudies for various reactions leading toloss of quality under variable time/tem-perature/humidity conditions.Support or conduct research into devel-opment of reasonable cost devices thatcould be at tached to food packageswhich could detect the impact of time,temperature, and humidity on shelf lifeof an individual food.

IMPACT ON TECHNOLOGY DEVELOPMENT

An open-dating system based on perish-ability time categories with a sell-by date,such as many States have now adopted, caninhibit efforts to improve processing technol-ogy, packaging methodology, and a distribu-tion system that would extend the shelf life ofmany foods. This is because there is no bene-fit gained in improving a food if it cannot besold at full price beyond a certain date aftermanufacture. However, if manufacturers areallowed to use the best-if-used-by date on avoluntary basis that they feel is reasonable,the incentive to do research to extend thedate may be greater than it is now.

From the consumer’s viewpoint, however,extending the date may be a processor’s at-tempt to make old foods taste and look good,at the risk of some additives. Many consum-ers today are extremely distrustful of food

additives used simply to extend shelf life.Also, consumer distrust may be a reason whyUHT (ultra-high temperature) milk has notbeen widely accepted in the United States.Because of improved sterilization techniques,this milk can remain shelf-stable for at least 6months at room temperature.

Another pitfall to consider is that too muchemphasis in product development may be putsimply on extending shelf life and thus de-crease efforts to develop a wide variety ofother interesting and convenient foods thatare enjoyable but which may not have an ex-tremely long shelf life. It is impossible, how-ever, to project such an impact at this time.

At present, theoretically accurate and reli-able shelf-life indicators for some types offood products exist that could measure the

38 ● Open Shelf -Life Dating of Food

reaction rate of food to both temperature andmoisture. However, these indicators are nottechnologically or economically feasible forindividual consumer-size packages.

If such indicators were in widespread use,food companies buying commodities or ingre-dients from other food companies could in-clude a value on the indicator as part of theirspecification for the ordered food. Some Gov-ernment contracts currently mandate use ofshelf-life indicators in shipping frozen foodcases. The use of indicators could well be ex-tended to other cases or pallets of food. How-ever, the indicators may never become inex-pensive enough to warrant their use on indi-vidual consumer packages, They would prob-ably cost at least as much as the packageitself.

Open dating could have a real impact on la-beling technology. There would be increasedincentive to develop quick-drying inks andways of printing on difficult surfaces, espe-cially at high speed. At present, it is not possi-ble to do this, and the materials are not avail-able, according to the industry. New unidirec-tional shrink-film that can be preprinted

without distortion as the label is appliedcould be the answer. It is currently used forbottle labels.

The other major issue is in the area ofquality standards. With the exception of thecommodities for which there are now qualitygrades and standards, no specific guidelinesexist for thousands of new, fabricated, andprocessed foods. However, the vast sourcesof existing knowledge on which Governmentand industry quality grades are based couldbe tapped.

If a best-if-used-by or sell-by dating systemwere imposed, research by Government, uni-versities, and industry laboratories would bestimulated. They would most likely center on:

1. shelf-life indicators,2. modes of deteriorations and quality indi-

cators,3. prediction of packaging requirements,

and4. more precise and objective methodology

for measuring changes in sensory quali-ty attributes.

Chapter VI

Alternative Open-DatingSystems

There are three basic systems that could be used for open dating: privatevoluntary system, mandatory system, and voluntary/mandatory system. With aprivate system, the industry develops and adopts standards voluntarily. With amandatory system, the use of open dates would be required by law. If the systemwere nationwide, the Federal Government would develop regulatory guidelines.Under a voluntary/mandatory system, only processors who elect to open datetheir products would be required to follow Federal guidelines.

An outline of the three systems is given in this chapter. For an analysis ofcongressional options among these systems, refer back to chapter I.

VOLUNTARY SYSTEMThis system is in current use because proc- be followed. Some processors date their prod-

essors who open date their food products ucts, while others do not. Those that do canhave chosen to do so. It is the preferred sys- select any date, can display it in any fashion,tern by many processors because it allows and can establish the date by any testing pro-flexibility in terms of: cedure.

1. whether or not to open date, This nonuniform system also can make it2. which products to date, more difficult for inventory control in the3. which date to use, and distribution channel, which can result in food4. which tests to use to determine the date. waste. In addition, it can increase food waste

in the home because the consumer does notOn the other hand, the system has led to know the food is approaching an unaccept-

confusion because there are no standards to able quality level.

MANDATORY SYSTEM

The mandatory system is used in 21 States is no uniformity on a national scale. Since na-and the District of Columbia for open dating tionwide distributors must meet differentof some food products—mostly milk and milk State requirements, the result is higher costs,products. As with the voluntary system, there which mean higher prices for consumers.

39

40 ● Open She/f-Life Dating of Food

A Federal mandatory system is preferredby many consumer representatives because itwould provide:

l . uniform regulat ions throughout theUnited States,

2. tighter inventory control in the distribu-tion channel, and

3. higher quality and nutritive levels forsome foods.

The major impact of the system would beon the processor. It would be very difficult forprocessors to comply with a mandated sell-byor best-if-used-by date within the next 2 to 5years, particularly for semiperishable andlong shelf-life foods. This is because there is alack of currently available data on shelf-lifestability for many food products. A mandatedsell-by or best-if-used-by date at this timewould force “manufacturers to guess aboutthe shelf life of their products and/or to ex-tend the known shelf life of one product to en-compass other similar products, which wouldnot necessarily benefit the consumer. Time tophase in the program would allow industry toestablish the necessary data on shelf life oftheir food products,

An alternative would be that the regula-tory agency could mandate that all food in acertain category had to meet a minimum date.If a company could not afford testing to dem-onstrate a longer shelf life, they could use theestablished, mandated minimum. If theycould demonstrate a longer shelf life, theycould use that date. If their product could notmeet the minimum shelf life, they wouldeither have to change the process, go out ofbusiness, or challenge the legality.

Objections to this alternative include thefact that a minimum shelf life for a productwould be similar to a standard of identity,which specifies the minimum composition ofmany processed foods. The Governmentwould have to identify criteria for each par-ticular food category and be able to defendthe criteria and the minimum shelf life. Forexample, if the Food and Drug Administration(FDA) developed a best-if-used-by date foreach product category, the agency would, in

effect, be assuring the public that the productis good.

It is more probable that the regulatoryagency involved would have to go to the op-posite extreme and determine the maximumdate that could be put on a product unless themanufacturer could prove otherwise. Sincethe process would have to be repeated foreach specific food, it would be very costly tothe Government.

Manufacturers could presently identifyand indicate the pack date if it were man-dated. The pack date would have to be de-fined as the date the product was put into thefinal consumer package for sale and use.However, there are problems in defining thepack date, which were discussed in an earlierchapter, mainly for multicomponent prod-ucts. If the pack date were mandated, theprinting system for the present codes wouldhave to be changed, but the system could beinitiated immediately.

The impact of a mandatory system on re-tailers and wholesalers would vary, generallyby size of operation. That is, smaller busi-nesses tend to have fewer inventory turn-overs per unit of time, so they could be ad-versely affected by out-of-date stock. Manda-tory open dating would likely have the leastimpact on national chains, the next least im-pact on smaller independent retailers/whole-salers, and the greatest impact on “mom andpop” stores. Convenience stores would be af-fected much like national chains.

Because of the potential adverse impact onsmall retail stores, a mandatory system mightexempt smaller stores, based on number ofemployees or gross dollar sales. However,such an exemption could mean that thesestores would receive products that werepulled after date from shelves of largernonexempt stores and shipped to them by dis-tributors (either manufacturers, representa-tives, or wholesalers). In the end, an exemp-tion could work to the disadvantage of smallretailers, regardless of the intent of the ex-emption.

Chapter Vi—Alternative Open-Dating Systems ● 41

Some consumers prefer a completely man- last as well as help stock rotation. Under adatory system, arguing that it would both voluntary system, these benefits are piece-educate consumers about how long a food can meal.

VOLUNTARY/MANDATORY SYSTEMThis system would combine the character-

istics of the voluntary and mandatory systemsby allowing the processors the choice of open-dating food products, but requiring that oncethey elect to do so, they must do it in a pre-scribed manner, This is essentially the systemused for nutrition labeling.

A voluntary/mandatory system would havea number of the advantages of the two othersystems, It would allow the processor tochoose whether or not to open date and toelect which products to date. However, sincethe processor who elects to open date must doit in a certain way, the result would beuniform open dating throughout the UnitedStates. Also, because processors would havea choice about open dating their products,this system should not have an adverse effecton smaller processors or retailers,

Of course, another factor to consider isconsumer pressure, Consumers could effec-tively pressure processors who do not useopen dating by purchasing products fromthose firms that adopt open dating.

This had been the case under the volun-tary/mandatory system on nutrition labeling,In 1973, when nutrition labeling regulationswere issued, very few products had a nutri-tion label, By 1978, 40 percent of the leadingnational brands, 25 percent of the remaining

national brands, and 44 percent of privatelabels displayed nutrition information on ma-jor packaged processed foods. In terms ofdollar sales, this represents 39 percent of the$24 billion of packaged processed foods sold. ’

The voluntary/mandatory system appealsto processors because it allows them the op-tion about open dating their products. It alsoallows them time to collect scientific data ona product-specific basis to determine thedates.

The system also appeals to many consum-ers because when products are open dated,every processor must meet specific require-ments. This provides for a more uniform sys-tem and reduces consumer confusion.

However, compared with the voluntarysystem, this system would increase costs toGovernment for developing and enforcing theregulations and would increase costs to in-dustry for complying with the regulations. Inaddition, developing the regulations in thefirst place would be time-consuming for bothGovernment and industry.

‘Raymond Schucker, “A Surveillance of Nutrition La-beling in the Retail Packaged Food Supply” (Washing-ton, D. C.: U.S. Department of Health, Education, andWelfare, Public Health Service, Food and Drug Admin-istration, 1978).

Chapter Vll

Enforcement and Liability

Open dating, as it exists today, has a built-in enforcement mechanismthrough the consumer. If a consumer is aware of date marking, understands it,and uses it, out-of-date products with a sell-by date will not be purchased at fullprices.

In most States, provision is made for sale of these products at a reducedprice. If the product cannot be sold, most manufacturers will take the productback and refund the retailer. The same is true if consumers feel a product is notup to the quality desired, they can return it and get their money back from mostretailers.

Some consumers feel, however, that returning a product is too time-consum-ing and unfair to them. They look to open dating as the institution of a fail-safesystem—i.e., anything purchased with an unexpired sell-by or use-by date wouldnot be bad; it would presumably be of excellent quality. Unfortunately, aspointed out in the previous parts of this report, such a guarantee is an impossi-bility, since unintentional abuse during distribution can severely reduce foodquality even though an item is dated.

The type of enforcement and liability would depend very much on the sys-tem used. With a pack date, there is no liability except from the standpoint ofmisbranding if it is made mandatory and left off the package. It would be up tothe Federal or State inspection systems to routinely survey the market for suchviolations, and the liability would be the same as at present for misbranding.The sell-by and best-if-used-by dates are another matter, however, as discussedin this chapter.

If the date were a sell-by or best-if-used-bydate, there could be two types of enforce-ment. The first would be before-date enforce-ment. In other words, if a date is based onsome standard such as loss of sensory qualityand the food is found to be below that stand-ard before the date is reached, it would be inviolation. The second type of enforcementwould involve offering a product for saleafter the date (beyond-date enforcement).

ENFORCEMENT

Before-Date Enforcement

Two types of before-date enforcement arediscussed and are presently used for enforc-ing labeling standards. Note that they lead tosubstantially different potential costs and lia-bility.

One method is to construct an enforcementscheme that would allow processors to estab-lish reasonable dates (be they sell-by or best-

43

44 . Open Shelf-Life Dating of Food

if-used-by) for each individual product and/orprocess within a product. Thus, canned greenbeans may have different sell-by dates, forexample, than canned peaches. Also, glazedfrozen shrimp may have longer sell-by datesthan frozen shrimp that are not glazed. Proc-essors in this scheme would be required tojustify the “reasonable” dates chosen, pre-sumably before instituting the system and ifasked by the regulatory agency. Tests anddata would be necessary to support the claimmade for reasonableness by the processor forhis date.

A second method could be for an enforce-ment agency to spot check products at theprocessor and retailer level via laboratorytesting. A regulatory agency could sampleproducts from the processor’s line or pur-chase products at retail and perform appro-priate laboratory tests for nutritional and/orsensory characteristics. However, the lab-oratory testing would vary from quick andsimple for some products to difficult and cost-ly for most products. The regulatory agencywould still need the information of the firstmethod to determine whether the productwas within the quality limits for the date set.

With spot-check enforcement, food produc-ers might feel the necessity of setting qualityspecifications for a date as low as possible inorder to protect themselves in case the prod-uct is severely abused during distribution.The quality standards would probably bemuch lower than those at which the proces-sors currently try to sell their products—inother words, lower than those the consumercurrently expects and finds. It should benoted that spot-check enforcement of labelclaims is presently done by Federal and localagencies. The Food and Drug Administration(FDA) is preparing to initiate this enforce-ment scheme to help enforce nutrition label-ing declarations.

The first method would be considerablyless expensive to enforce and would not leadto a decline in quality specifications for thedate. In addition, the first alternative wouldavoid liability questions raised by the secondalternative. The second scheme raises ques-

tions about the extent of manufacturers’ lia-bility, especially if the product tested werepurchased at retail. If the product chosen fortesting had been abused in the distributionchannel (e.g., high temperature in frozenfood), processors could conceivably be heldresponsible for the actions of distributorsover which they have no control.

Beyond-Date EnforcementTwo alternatives are possible. One is com-

plaint-based enforcement, the other is spot-check enforcement.

Complaint-based enforcement would in-volve a consumer’s return of a beyond-dateproduct, or the out-of-date product wouldsimply go unsold, thus indicating consumerdispleasure or disinterest. This system wouldbe possible with sell-by or best-if-used-b y

dates, but not a pack date. Enforcement costswould be minimal.

A second alternative would be to have anenforcement agency randomly spot-check re-tail stores for merchandise that was beyonddate. Costs of this alternative would be con-siderably higher than complaint-based en-forcement. In the case of pack dates, spotchecks could be made at the origin of retailpackaging, so this alternative could cover anytype of open date.

Again, the manufacturers who set the high-est standard would run the greatest risk ofbeing in technical violation of their ownstandard. For this reason, food should beallowed to be sold after a sell-by or best-if-used-by date, since the date is only an esti-mate.

Especially with semiperishable and longshelf-life foods, there should be no discernibledifference between quality shortly before thedate and shortly after. Even with perishablefoods, open dating is not a safety issue, sincethere are laws currently in effect that make itillegal to sell unsafe food. If consumers re-fused to pay full price for over-age food, itcould be offered at a reduced price.

Chapter V//—Enforcement and Liability ● 45

FEDERAL/STATE

As discussed earlier in this report, 40 per-cent of the States have some type of manda-tory open-dating law that they are currentlyenforcing. Thus, an alternative to exclusiveFederal enforcement would be cooperationwith the States. Basically, this type of cooper-ation could be achieved either through cost-sharing programs or model regulations,

Cost-sharing programs can be in the formof contracts or grants. The most common ar-rangements are 50-50, although there aresome arrangements with 80 percent Federaland 20 percent State and some with 90 per-cent Federal and 10 percent State. Contractsare formal agreements between Federal andState governments to perform specific tasksover a specified time period. Grants are lump-sum payments to States for use at their dis-cretion in a general area.

OTA found that Federal and State officialsprefer contracts over grants for the purposeof cooperating on enforcement. The advan-tage for Federal officials is that specific tasksare identified and both parties know what isexpected for satisfactory performance. Forthe States, the advantage is that in mostcases, multiyear contracts can be establishedwhich will provide a continuous source offunds for the States to perform their tasks.

Grants are viewed as “one-shot” affairs,and States cannot depend on them for con-tinuous funding, Federal officials also take adim view of grants because they are not spe-cific in terms of tasks to perform. This makesit difficult for Federal officials to judge eachState’s performance.

The basic problem with these cost-sharingprograms is nonparticipation by the States.The program works only if States feel there isa need for a specific activity or that they aregoing to benefit directly. Thus, States thatpresently have open-dating legislation will bemore likely to participate than those that donot. If States do not participate, there is noequivalent means of enforcement. This is thepresent situation with the Fair Packaging and

ENFORCEMENT

Labeling Act (FPLA). FDA is doing little FPLAenforcement in States where there are nocontracts.

In the final analysis, the Federal Govern-ment must assume enforcement responsibil-ities if States decide they do not want to coop-erate. Experience with cost-sharing or par-tial-funding programs such as the WholesomeMeat Act indicate that the States are not like-ly to cooperate. One-hundred percent Federalfunding may have to be provided to ensureState cooperation. Otherwise, State officialsare not going to look with much favor or givepriority to a program the Federal Governmentwill have to take over if States are not willingto do it.

To qualify for 100-percent” funding, Statesmust have a law that is at least as encom-passing as the Federal law. To illustrate, if aState has no law or a law that is less than theFederal law, it would not qualify for funding.However, if the State had a law that wasmore encompassing than the Federal law, itwould qualify.

States adopting the Uniform Model Acthave a history of adding to their laws andacts, areas that are above and beyond thoseof the Federal Government. Thus, if an ab-solutely uniform open-dating law or regula-tion is desired, using State enforcement willnot ensure this outcome,

The alternative to a cost-sharing programis a model State regulation applicable to Stateand local jurisdictions. The National Bureauof Standards has designed such a model foropen dating. The model provides for the useof a sell-by date on perishable and semi-perishable foods but does not address thebasis on which to establish the date and ex-cludes products for which a date would beuseful and feasible. Four States have adoptedthe model to date. As a result, the Associationof Food and Drug Officials is consideringpreparing its own model regulation for opendating.

46 . Open Shelf-Life Dating of Food

The Association has designed the UniformFood, Drug, and Cosmetic Act, which hasbeen adopted by some States. The Act couldbe amended to include food-labeling areaslike open dating.

The Act as currently written is State-ori-ented, since each State can change the Act tomeet its individual situation. It is purely amodel and not sufficient in terms of enforce-ment. A State may adopt the model regulation

but may not enforce it if funds have not beenallocated.

Although there is the possibility of Federalfunds for States that adopt the model Act,Congress would have to first amend the Food,Drug, and Cosmetic Act. Presently, FDA doesnot have the authority to establish contractsfor which it does not have basic responsibilityby law.

LIABILITY

There is a difference in establishing liabil-ity between open-date labeling and mostother food-labeling requirements. For exam-ple, in nutrition labeling, basically only themanufacturer, not distributors, is involved incompliance, although abuse in distributioncan lead to labels that overstate nutritionalvalue. In open-date labeling, processors,wholesalers, and retailers are all involved incompliance. If a retailer sells a product at fullprice that is out of date, the retailer, not themanufacturer, would be liable. Naturally,wholesalers and retailers are concerned thatif a Federal open-dating system were imple-mented, this would in effect increase theirliability.

At present, there is no definitive legislationor judicial definition of the legal significanceof an open date. A search of the literaturefound no court decisions during the last twodecades on the question of liability for spoiledfood that has been open dated. Thus, the dis-cussion of this question must be speculative.

In order to assess possible legal conse-quences, it is necessary to make certain as-sumptions about the intent and effect of aFederal open-dating requirement. First, sucha requirement must avoid as much as possi-ble the technological problems associatedwith open-date labeling of some foods. Sec-ond, it must provide for specific, uniform, andscientifically sound criteria by which thechosen date is established and its validity

measured. Third, it must be designed tominimize confusion about the attributes of afood product. That is, the objective of opendating is to increase consumer awarenessabout food freshness; it is not an indicator ofthe safety of food. As indicated earlier in thisreport, consumer confusion on this pointcould have serious consequences.

Liability Under the Food, Drug,and Cosmetic Act

Food manufacturers and retailers could besubjected to increased liability exposureunder the Federal Food, Drug, and CosmeticAct (FDCA) if a Federal open-dating require-ment is intended to relate to the misbrandingand adulteration provisions of that statute.To the extent that any food is marketed in away (for example, without a sell-by or best-if-used-by date, if required) that it becomes mis-branded under FDCA, it is an illegal commod-ity, Additionally, the sale of “spoiled” food isprohibited by the adulteration provision ofFDCA, whether or not the label of a productbears an open date.

Liability for such misbranding would flowto the manufacturer who failed to properlylabel the food, as well as to the intermediatedistributors and retailers who sold, or heldfor sale, the misbranded product. Liabilitywould not extend to distributors and retailerswho could demonstrate that they received the

Chapter V/l—Enforcement and Liability ● 4 7

misbranded food and delivered or proffereddelivery of it in “good faith, ”

The FDCA provision that declares as mis-branded any food article the label or labelingof which is false or misleading, if taken liter-ally, raises difficult problems from both acompliance and enforcement standpoint, Theleast of these problems involves food prod-ucts the label of which might declare thatthey were packed on a particular date. If the“pack date” is not accurate, the product ismisbranded and the manufacturer or packerof the product would be liable for such mis-branding. (A retailer who has purchased themisbranded product in good faith and sells itor holds it for sale would probably not beliable. ) Pack dates are definite in time andthus can be objectively determined to beeither accurate or false.

On the other hand, the other forms of opendates that might be selected (“use by, ” “sellby," “best-if -used-by,” etc. ) only can provideapproximations of the ultimate shelf stabilityof the labeled products. Such dates offerfreshness guidelines, but nothing more, andcan never be precise. Different food manu-facturers are likely to have different qualitystandards for their products, limiting the“precision” and significance of open dates.Moreover, storage or handling variables towhich a product is subjected during its dis-tribution cycle, or even during home storage,can affect the accuracy of all dates otherthan a pack date on the package.

The sell-by date raises an additional issue.The meaning of this date is somewhat vague.A sell-by date suggests that the product canbe consumed for a reasonable period of timeafter the date with no recognizable differ-ence in the quality of the food. The exclusionof information that indicates the ensuing con-sumption period could constitute the omissionof a material fact rendering the product mis-branded. This should be specifically ad-dressed in the legislative history of any open-dating provision.

Literal application of FDCA could result inmisbranding of a product because of distribu-

tion abuses—abuses that would render theopen date inaccurate or misleading. For in-stance, a phrase such as “use by’* on a foodlabel might lead a consumer to believe thequality of the food will remain unchanged aslong as it is consumed by the stated date, Ifsuch a product were left an unusually longtime in the sun on a retailer’s loading dock,for example, that inference would no longerbe true. If and when it is discovered that theproduct is “outdated,” it is unlikely that thefact of its storage irregularity would also bediscovered. One possible solution to this prob-lem might be to provide that as long as a la-beled date is objectively accurate in light offoreseeable marketing conditions at the timea product is labeled, when measured in termsof those criteria specified for the establish-ment of such a date, that product should beconsidered to be in compliance with FDCA.

Literal application of FDCA might or mightnot also result in an illegal product becauseof abuse in distribution. The same issuearises with respect to the declared net quan-tity of contents of packaged food. The lawpermits FDA to enforce it sensibly by deter-mining the average net quantity of contents.There is nothing inherent in FDCA that wouldsuggest that this approach would not beequally applicable for open dating of food.

Civil Liability

In addition to liability under FDCA, thereare two theories under which a manufac-turer, distributor, or retailer could be heldcivilly liable to a consumer and/or third partywho purchases and/or consumes a “spoiled”food product, the label of which bears anopen date, The two potentially applicabletheories are: 1) strict product liability undertort law and 2) warranty l iabi l i ty undereither the Magnuson-Moss Warranty Act orthe Uniform Commercial Code. The viabilityof either of these theories will depend primar-ily on what an open date—and especially anyqualifying terminology accompanying thedate (“use by," “best-if-used-by,” “freshnessguaranteed if used by,’” etc.)—means to aconsumer purchasing the food product. For

—

48 . Open Shelf-Life Dating of Food

example, if an open date and/or accompany-ing terminology were construed to constitutea promise, guarantee, or other affirmation offact with respect to a food’s quality, and aconsumer, relying on the dating information,purchased a food that “spoiled” prior to thedate, that consumer might be able to recoverdamages under a breach of warranty theoryof civil liability.

Research in the individual States withopen-date labeling found no court decisionson the question of liability for spoiled foodthat has been open dated. Since product lia-bility is almost entirely a matter of State law,a discussion of the theories would be specu-lative.

The criteria by which an open date is es-tablished and by which food quality is meas-ured, as well as the legal meaning and signifi-cance of the date, will ultimately determinethe viability of the theories noted. These mat-ters should be thoroughly explored and re-solved in the legislative history of any open-dating provision. In this regard, it is impor-tant that the limitations of open-date labelingbe addressed. The legislative history of anyopen-dating provision must make clear thatopen dates are only guides to freshness, notsafety indications nor guarantees of productfreshness. Otherwise, unintended and poten-tially onerous legal ramifications could ariseunder both criminal and civil law.

Chapter VIII

Economic and Social Costs

Economic and social costs of open dating are an important consideration.Based on the previous chapters, costs can be discussed in terms of: 1) establish-ing shelf life, 2) putting the open date on each package, 3) enforcement, 4) com-parison with nutrition-labeling costs, and 5) food disposal. At the present time,there are no exact cost estimates for each of these areas. The costs presentedare the best estimates available.

COSTS OF OPEN DATING

Establishing Shelf Life

Experts interviewed by OTA grouped thepossible costs of establishing the shelf life ofindividual food products into two categories.The first, for perishable and semiperishablefoods, would be about $100,000 per item, re-quiring at least one investigator and a techni-cian plus facilities for 1 year. Nonperishableswould cost $200,000 per item, taking 2 yearsto determine. These would be one-time costs,but future adjustments in the shelf life wouldhave to be made with each change in productformula, package used, and mode of distribu-tion, thus adding to costs in the long run.

Dating the Package

The cost of putting a date on food packageswill vary widely, depending on type of pack-age and method of date placement. For exam-ple, for canned products, existing closing ma-chines can be modified to emboss the opendate on the can for a cost of between $1,000and $3,600 per machine. This is a low cost ona per-can basis. However, for perishableproducts, equipment costs can vary between$1,500 and $15,000 per food product.

Enforcement

In terms of enforcement, if the programwere self-enforcing— that is, if there were nopenalties for out-of-date food products andthe only enforcement were consumers re-fusing to pay full price for out-of-date food—there would be no cost of enforcement per se.If a legal penalty were involved, the cost ofenforcement could be more than $500,000per year. ’

Even if the program were self-enforcing,there would be considerable cost in foodeither sold at a lower price or returned to themanufacturer as unsalable. This cost wouldvary widely with the length of shelf life, reli-ability of the distribution system, and popu-larity of the items. At present, this cost wouldbe difficult to estimate.

‘U.S. Congress, Consumer Food Act of 1976, report toCommittee on Commerce and the Committee on Laborand Public Welfare, U.S. Senate on S. 641, Mar. 4,1976.

49

50 ● Open Shelf-Life Dating of Food

Comparison With Nutrition Labeling

Because there are no good estimates oncosts of open dating, a comparison with asimilar area of labeling—nutrition label-ing—is worthwhile. A survey conducted bythe Grocery Manufacturers of America in1975 indicated that $8.4 billion worth of foodproducts would have nutrition labeling thatyear, For those products, the initial average

cost of putting the information on labels perdollar of sales was estimated at .004 cent,and the average continuing cost at .00016cent per dollar of sales. Thus, nutrition label-ing, which involves complex testing proce-dures and more information to be printed onthe label than does open dating, costs aminimal amount once established. The sameshould be true for open dating.

IMPACT

Processors

The greatest impact of an open-dating sys-tem would be on the food processors, espec-ially if the system were completely manda-tory. In this case, much research at high costwould be entailed for each product/packagesystem, and at present, there may not beenough scientists or laboratories trained oravailable to do the total job in just a fewyears, Industry would need to apply new ormodified films, adhesives, and packaging ma-chines. With a voluntary/mandatory labelingsystem, the same costs would exist, but onlythose companies who could afford the costswould undertake the job. This would not tendto reduce market competition as might hap-pen with a completely mandatory sell-by orbest-if-used-by system.

Wholesalers and RetailersWith a voluntary/mandatory or completely

mandatory system in which enforcement andliabilities required segregation of product,retailers would have two related costs. Thefirst would be more time to inspect shelves toensure that no out-of-date products werepresent, and the second would be using spaceto sell out-of-date products at a reduced cost.The latter could be eliminated by returningthe product to the food manufacturer, butthat would mean an additional transportationcost and either a remanufacturing or disposalcost. At any rate, the result would be a priceincrease to the consumer.

Costs of various disposal schemes for out-of-date products can vary depending on thescheme and product category. For example, ifmandatory open dating were imposed onfresh meat and poultry, without allowancefor reconditioning and redating, the addi-tional costs of open dating could be burden-some for some retailers. The impact would begreatest on smaller retailers who tend tohave fewer inventory turnovers. Also, eco-nomic incentives already exist for retailers tominimize the amount of meat reconditioned.

Alternative disposal schemes at retail in-clude marking out-of-date stock down inprice, allowing return to processors (whereappropriate), giving the food t o charities, orsimply disposing of it. The first of these is like-ly the least expensive to the distribution sys-tem in the long run, while the latter is likelythe most expensive.

Social costs from mandatory open datinginclude potential for less variety of sizes andmore products out-of-stock on retail shelves.Such reaction would be logical for retailers inan attempt to minimize past-date merchan-dise on their shelves.

Consumers

The overall result of open dating, whethervoluntary or mandatory (except for a packdate) would be to increase the cost of food tothe consumer, since all the above costs would

Chapter Vlll—Economic and Social Costs ● 51

be passed on as increased price, ’ Experts onthe OTA working panel could not make an ex-act estimate of increased cost, but thought itcould be between 0.1 and 1 cent per packageof food.

The greatest impact on consumers otherthan cost would be increased education onthe storage and handling of foods, whichmight mean increased quality at point of con-sumption and an opportunity for purchasingout-of-date bargains.

Government

With a required open pack date, the over-all cost to the Federal Government would notbe much more than under present food pack-age screening and recall procedures on thebasis of misbranding.

If the Government were to mandate a use-by or best-if-used-by date with Government-set standards of quality, a large share of cur-rent FDA and USDA budgets would be re-quired for the research to set such standardsfor all packaged foods. Since it would have tobe on specific products, consumers wouldlikely complain that the Government is doingthe industry’s job. In addition, the size of theenforcement and legal force would have to beincreased to cope with the problem of retailinspection and control.

If the labeling systems were voluntary, butwith a mandated label format and qualitystandards set by the food companies, therewould be little cost impact on the Governmentexcept through FDA and USDA educationoffices to help the consumer understand thelabel. However, based on problems with nu-trition-labeling-education costs, this could berelatively expensive. Other costs to Govern-ment would be in enforcement if the correctlabel format were not used. Another problemwould be in setting standards for removal orsegregation of out-of-date food, especiallywith respect to the price reduction thatshould be used,

Chapter IX

Array ofCongressional Options

This chapter provides a detailed explana-tion of the interaction among the variousissues surrounding open shelf-life dating. Asstated in this report, there are many possiblecombinations, each of which represents acongressional option. The interaction amongthese is detailed below.

The issues discussed in this report thatgive

1.

2.

3.

4.

rise to congressional options are:

Whether open shelf-life dating will beimplemented by regulation through anexecutive branch agency or requiredthrough a specific law;Whether open shelf-life dating should bevoluntary, voluntary/mandatory, or man-datory;Which products or product categorieswill be exempt from open shelf-life dat-ing or will have a voluntary/mandatoryor mandatory date established;The method chosen for open shelf-lifedating.

There are important aspects of theseissues that interact to create an open shelf-life dating system for food products. This is il-lustrated by the decision tree of figure 1.

The first branch, path A, illustrates thedistinction between regulation through theappropriate executive branch agency or re-quiring specifics through statutory law. Thisis a basic option that underlies each issuespecific to open shelf-life dating.

The second branch, path B, illustrates thethree possibilities for the degree to whichopen shelf-life dating would be mandatory.One possibility is to specifically exempt cer-tain products or product categories or toallow present voluntary dating to continue.Another possibility is to opt for a volun-tary/mandatory program for certain productsor product categories. A third possibility is tomake open dating mandatory for certainproducts or product categories.

The third branch, path C, illustrates thatany of the previous options could be appliedto product categories such as perishables,semiperishables, or long shelf-life products.Of course, specific products or more narrow-ly defined product categories also would beappropriate at this point in the decision tree.As an example, a branch could be “strawber-ries” or “bulk fresh fruits and vegetables, ”rather than “perishables.”

The extreme right-hand side of the decisiontree illustrates the options for the methodused to convey an open shelf-life date. Theseinclude pack, sell-by, best-if-used-by, andcombination dates. Each of these methods ofdating represents an option by product orproduct category.

The decision tree clearly illustrates the in-teractive nature of the options. That is, if aparticular option is chosen under one of thefour issues, the impact of it will be differentdepending on which options under the otherissues are chosen.

53

54 . Open Shelf-Life Dating of Food

——

To clarify the interactions among the op-tions, several examples are given using figure1 as the basis for the example. These ex-amples will follow specific paths of the deci-sion tree.

Congress might opt to allow the appropri-ate executive branch agency to set volun-tary/mandatory open shelf-life dating on per-ishables using a sell-by designation for thedate (denoted as decision path “A” in figure1). This particular path through the decisiontree would mean that the specific decisionslikely would be made by the appropriate ex-ecutive branch agency, Also, the specifics ofthe open-dating system such as the products

Combination

or product categories and the method for des-ignation of the date would be accomplishedby regulation issued by the executive branchagency rather than written into the law byCongress. Congress can stop at any point inthe decision tree once the decision is made toallow an executive branch agency to put opendating in place via regulation rather thanstatutory law.

Note that the alternative paths through thedecision tree are not mutually exclusive. Onepath may be chosen for a particular productcategory or method for dating while an en-tirely different path is chosen for anotherproduct category or method.

Chapter /X—Array of Congressional Options ● 55

Another specific path through the decisiontree is for Congress to write a law that wouldspecifically exempt long shelf-life productsfrom open dating (denoted as decision path“B” in figure 1). This would mean that manu-facturers of many canned or frozen productswould be exempt from a Government pro-gram but could still voluntarily open da tetheir products, as some presently do.

A final example is that C o n g r e s s c o u l dwrite a law that would place mandatory opendates on perishable products using a sell-bydesignation (denoted as decision path “C”’ in

figure 1). The implementation would be theresponsibility of an executive branch agency,but the law would be specific with regard toproduct category and method used to desig-nate the open date.

Similar open shelf-life dating systems aredepicted by fol lowing the various decis ionp a t h s t h r o u g h t h e d e c i s i o n t r e e . S e v e r a lpaths may be combined to form the basis ofan open-dating system. The consequences ofthe various opt ions are found in the maintext.

APPENDIXES

These appendixes provide more detailed information on open shelf-life dating of food.

Appendixes A, B, and C provide technical background on the ap-plicability of open dating of food. They summarize a report prepared forOTA by the Department of Food Science and Nutrition, University ofMinnesota, under the direction of Dr. Theodore P. Labuza. These appen-dixes were prepared by Dr. Labuza and Linda Kreisman and were re-viewed by the OTA panel on open shelf-life dating of food.

Appendix D is a summary of the status of open shelf-life datingregulations in selected foreign countries and international organiza-tions. It is based on a paper prepared for OTA by Dr. Amihud Kramer.

Appendix E is a detailed bibliography on open shelf-life dating offood.

Appendix A

Application of Open Dating toSpecific Foods

This appendix contains aOTA-C-78-001 for various food

condensation of data on shelf life collected in contractcategories. In that contract. the specific modes of deteri-

oration were analyzed, and shelf-life plots presented for each mode. The reader is re-ferred to the specific data and literature references in that report.

In this review, the foods have been broadly classified into perishability categories,since many States have legislated open dating on a perishability basis. Three categorieswere chosen, based on normal processing, distribution, and handling conditions:

Perishable--foods of less than 30 days shelf life in which the major problem is high-temperature abuse.

Semiperishable--foods of greater than 30 days but less than 6 months’ shelf life.Long shelf-life foods-these are foods of greater than 6 months’ shelf life. In some

cases, they have been described as nonperishable foods. However, as noted in thisreport, all foods decay at some rate for certain environmental conditions.

It is noteworthy that this classification is not actually based on the food itself but isbased on the food/process/package/storage conditions. Thus, a long shelf-life food like acanned food could deteriorate in less than 1 week if held at 400

to 500 C or in a few days ifopened and held at room temperature. This point must be remembered when the regula-tory aspects of shelf life are considered. It must also be noted that it is difficult to actuallyseparate the semiperishable and long shelf-life foods.

Modes of deterioration. Fluid milk and fer-mented milk products such as buttermilk, yogurt,and cottage cheese deteriorate because of: 1) bac-terial growth and 2) lipid reactions, includingboth autoxidation and enzymatic hydrolysis. Theshelf life is usually from 7 to 14 days under refrig-eration conditions.

Milk products are an ideal medium for growthof a number of psychrophilic bacteria. The opti-mum temperature for their growth is 200 to 30° C,but they also grow well, although more slowly, at

refrigeration temperatures. Following pasteuriza-tion, it is generally only the more heat-resistant(thermoduric) bacteria, some of which can be psy-chrophiles, that remain. Their numbers should bequite low, and at low temperatures (0° to 10° C),the milk should have a fairly long shelf life. Thus,the best way to prevent spoilage is to prevent re-contamination after pasteurization. Growth ofpsychrophiles in milk can lead to a variety of off-flavors and defects. Among these are bitter,fruity, rancid, stale, and putrid flavors, and ropi-ness in milk. One problem associated with estab-lishing standards for acceptable levels of bac-

59

60 ● Open Shelf-Life Dating of Food

teria in milk is that different species produce dif-ferent types and intensities of off-flavors andodors. The off-flavors may be detected at 104 col-ony forming units per milliliter (cfu/ml) of onespecies and not until 107 cfu/ml of another spe-cies, The temperature coefficients (Q10's)* for mi-crobial growth in milk range from 3 to 30 andaverage around 6.

Enzymatic hydrolysis of triglycerides in milkcan yield free fatty acids that cause rancidflavors even when present in very low concentra-tions. Lipase and other such enzymes are general-ly inactivated by pasteurization, but certainmicrobes can produce the enzymes as they grow.Oxidation of unsaturated fats and phospholipidscan lead to a variety of off-flavors. Sunlight,fluorescent light, metal ions, excessive agitationas in homogenization, and a small amount of as-corbic acid and riboflavin favor or catalyze theoxidative reaction. Addition of antioxidants tomilk is not allowed in the United States. Tocopher-ols are the only antioxidants known to be presentnaturally, although sulfhydryl groups producedduring pasteurization also have antioxidant prop-erties. The use of opaque- or colored-glass milkcontainers reduces the catalysis of autoxidationreactions. The Q10’s for lipid reactions in milk arefrom 3 to 4, much lower than for microbialgrowth.

In milk conforming to current health standards,off-flavors and off-odors occur more quickly thando actual safety hazards or significant nutrientloss. These sensory quality defects should be usedto set the end of shelf life.

Pack date. In pasteurized milk, the pack date isthe date of pasteurization. Milk quality after pas-teurization is highly dependent on sanitary han-dling, temperature control, and protection fromlight. Without a knowledge of these processingand distribution parameters, the pasteurizationdate is not very useful to the consumer. For exam-ple, milk unopened in the carton normally is ex-pected to have a shelf life of 7 to 10 days at 6° C. Ifheld at 0° C, it can last for 20 to 30 days with highquality, but the consumer usually does not knowthis.

Sell-by date. This dating system is currentlyused in several States for milk. Usually, the sell-bydate is set as a certain number of days from proc-essing (e.g., 10 days) for all pasteurized milkwithin a given State. This system has the advan-

*A measure of sensitivity of food to temperature is called thetemperature coefficient (Q,,,). See app. B, equation 8.

tage of forcing all processing and distribution sys-tems to conform to a minimum standard. It, how-ever, also has the disadvantage of discouraginghigher quality practices and inhibiting introduc-tion of new technology.

For example, ultra-high temperature (UHT)milk produced in Europe is milk pasteurized atvery high temperatures, giving it a much longershelf life (3 to 4 months) at room temperature.Since it would be classified as pasteurized milk, itmight have to be labeled as a perishable food andthus there would be no technological advantage inproducing it. A system of setting the shelf lifeseparately for each batch of milk depending oninitial quality and on quality of processing anddistribution conditions would be more accurateand just. However, to do this would require fur-ther studies to develop time/temperature specifi-cations on microbiological and esthetic milkqualities, which could be expensive. It would alsorequire a flexibility within the dating system toadjust to changes in processing and distributionsystems.

Best-if-used-by date. The high sensitivity ofmilk to sani tary t reatment and temperaturemakes this date unsatisfactory. This is especiallytrue if control of distribution is not undertaken.On the other hand, with good distribution controland knowledge of the initial quality parameter,one could theoretically place an end-of-shelf-lifedate on fluid milk.

Fresh “Bakery Products

Modes of deterioration. The various modes bywhich breads and cakes deteriorate include:1) microbial growth, primarily visible moldgrowth on the surface of the product; 2) moistureloss causing hardening; 3) oxidative rancidity; 4)nutritional losses; and 5) staling.

The baking process is similar to pasteurizationin that both enzymes and micro-organisms are de-stroyed by the heat. Thus, bread may be stored atroom temperature in spite of its high water activi-ty. By the time microbial growth begins to be aproblem, the bread has usually been consumed orother modes of deterioration have already limitedshelf life. Calcium propionate is often added tobread as a mold inhibitor to slow this process.Moisture loss can be kept to a minimum by use ofmoisture-proof packages, although it can be thelimiting factor in cakes packaged in cardboard.

Staling usually occurs before either oxidativerancidity or significant nutritional losses. This is

Appendix A—Application of Open Dating to Specific Foods “ 61

especially true of bread and usually true forcakes, in which rancidity can occasionally be aproblem. Vitamin losses occur very slowly inbakery products. Loss of available lysine throughnonenzymatic browning occurs more quickly butis not a significant problem, since bread is not asignificant source of lysine in the diet.

Staling is by far the major mode of deteriora-tion in fresh bakery products. Effects of staling in-clude changes in taste and aroma, increasedopacity of crumb, increased crumbliness, and in-creased hardness of crumb (with or without mois-ture loss). Many factors affect the rate and extentof staling, including the protein content of theflour used, pentosan content, and monoglycerideand diglyceride additives. Staling is one of the fewdegradative reactions in foods that proceedsfaster at lower temperatures, having an inverseQ 10 of 1.5 to 2.0. The shelf life of breads is usuallyconsidered to be about 2 days and that of cakesabout 1 week.

Aside from the possibly toxic effects of consum-ing large amounts of moldy bread, there are littleor no safety considerations in determining theshelf life of fresh bakery products. Most people, infact, would reject moldy bread even when one col-ony forms. Nutrient loss is of minor considerationsince it occurs much more slowly than sensoryquality losses caused by staling.

Pack date. The pack date for bakery productswould let the consumer know when the producewas made. This would be acceptable for bakeryproducts, although not the most desirable type ofopen date. With a pack date on the product, theconsumer may expect bread to be fresh when it isin fact very close to staleness. On the other hand,for cakes, with a shelf life of about 1 week, con-sumers may feel the product is too old when, infact, there is considerable high-quality life left.The only way a pack date would be acceptablewould be if people had an excellent knowledge ofshelf life.

Sell-by date. A sell-by date sets a limit on theacceptable amount of staling of bakery productssold at full price in the marketplace without mak-ing a judgment of the amount of staleness the con-sumer would personally tolerate when actuallyeating the product. Sell-by dates are presently re-quired in several States. Bakeries in these Stateshave found that consumers do tend to pick thefreshest product, but this presents no real prob-lem since deliveries are made every day or everyother day. They also have experienced no trouble

in selling the average products at reduced pricessince they are still edible and have lost no nutri-tional quality.

Best-if-used-by date. This date tells consumersthat for maximum freshness they should use theproduct by that date without fear that if they donot, they must throw it away. This date would alsobe beneficial for the bakeries. They could sell theproducts past that date at a reduced price andtherefore would not have to dispose of the productas could be the case with a use-by date.

For fresh bakery products, either the sell-by orbest-if-used-by date would be suitable.

Fresh Meat

Modes of deterioration. There are essentiallytwo modes of spoilage for fresh meat products:bacterial growth and loss of appropriate color.

Consumers relate the characteristic red colorof fresh meat with quality and freshness. This redcolor occurs when red oxymyoglobin is formedbecause of the oxidation of purplish myoglobin.Exposure to air and light causes the color changeof oxymyoglobin, generally within 24 hours,although packaging under a low oxygen atmos-phere can delay the reaction. The color change isalso extremely temperature-dependent as re-flected in a high Q10, of 20 to 35. It should be real-ized that although the color may change, the foodstill has high flavor quality and nutritional value.With some meat such as pork the use of a color in-dex is not possible because of its initial color.

Bacterial spoilage is caused mainly by psycho-trophs and, with the exception of ground beef, isprimarily a surface problem yielding slime, off-colors, and off-odors. The shelf life of fresh meatis generally 3 to 4 days at refrigerated tempera-ture, considerably longer than that for brown-color development. The critical factors to guardagainst microbial spoilage are: 1) maintenance ofproper temperature, since the Q10’s are relativelyhigh (3 to 8), and 2) maintenance of proper sanita-tion to keep the original bacterial load low. At 5°C, ground beef with an original load of 105 cells/ghas 2 more days of shelf life than that with anoriginal load of 107 cells/g.

The package atmosphere can also drasticallyaffect shelf life. A carbon dioxide (CO2) atmos-phere will lower the pH of the meat surface andretard growth, increasing shelf life by severalweeks without any significant nutritional losses.It should be noted that the history of the animalprior to slaughter can also affect shelf life.

62 ● Open Shelf-Life Dating of Food

Proteolytic psychotropic bacteria grow morequickly in fresh meat at proper storage conditionsthan do pathogenic bacteria. Thus, the productionof slime, off-flavors, and off-odors is rapid enoughto occur before the possible development of safetyhazards of pathogenic growth. Using color changeas a sensory-quality criterion also means that sen-sory changes occur sooner than any safety haz-ards or significant nutrient loss. However, thesecolor changes can cause rejection of the meatwhile it still has high flavor quality.

Fresh meat that is cut and prepared in the re-tail store, is not frozen at any time during its stor-age life, and is not packaged in any container orwrapping prior to sale could be exempted fromopen dating. The quality of fresh meat describedabove can be determined by sight, touch, andsmell before purchase is made, In addition, therewould be problems in physically placing a date onindividual items, and the cost of such a programwould be prohibitive.

For fresh meat that is packaged and/or frozenat some time during its storage life, an open dateis more meaningful because consumers have moredifficulty determining the quality of the product.An open date would be of more use to consumersunder these conditions and would be more feasi-ble placed on the package as opposed to the indi-vidual item.

Pack date. Almost all fresh meat is packaged bythe retailer who deals directly with the public.This meat may have been slaughtered anywherefrom 1 day to 2 weeks previously. Since carcassesof properly handled beef are essentially sterile in-ternally, it is the packing procedure that initiatescolor and bacterial spoilage, Thus, the pack dateis a good index in determining the shelf life. Sincethe shelf life of fresh meat is relatively shortbeyond the pack date, this date may be sufficientfor consumer use and understanding, However,many people freeze meat at home, and the packdate does not give them any idea of the frozenproduct shelf life.

Sell-by date. The sell-by date may not be anymore useful to the consumer than a pack date forfresh refrigerated meat because it does not tellthe consumer the time at which quality changeswere initiated. However, if the marketer has goodquality control, it represents a better method thanthe pack date, as it might reduce wastage,

Best-if-used-by date. In the case of fresh meat,this date could be “for highest quality, use orfreeze by .“ This date might be most useful tothe consumer. However, as evidenced by the Q10’sof the deteriorative reactions, high temperature

can result in very rapid deterioration of freshmeat. Thus, the potential for consumer abuseprior to the date may be too great for this date tobe a practical alternative,

Poultry

Modes of deterioration. Discussion of themodes of deterioration of quality will be limited tothose changes occurring after death that affectwholesomeness and fitness for food. These in-clude: I) microbial decay, 2) pathogen growth, 3)sensory quality changes, 4) chemical and enzy-matic degradation affecting color and rancidity,and 5) physical decay.

Hundreds of different species of micro-orga-nisms have been reported to grow in poultry meatand may or may not be pathogenic. In the UnitedStates, fowl foods once were the most frequentvehicle of dissemination in outbreaks of food-borne infections, and Salmonella were the mostimportant organisms implicated in these out-breaks. However, according to the Center for Dis-ease Control, poultry has become a minor vehiclefor food poisoning in recent years because of bet-ter process controls.

Microbial growth during storage may or maynot cause decay, depending on the type of orga-nism (proteolytic or nonproteolytic). Slime forma-tion occurs at a level of 108 to 109 organisms persquare centimeter (cm2) of surface, and sensoryspoilage is detectable at 107 to 108 organisms perc m2. Low temperature is the best preventionagainst microbial growth. Growth occurs onlyvery slowly below – 12° C, and it is importantthat the temperature doesn’t fluctuate above that,Since the Q10 for growth is about 3.

Flavor changes are affected by the sex and ageof the animal, amount of fat, and surroundings ofthe carcass. They can be monitored by the degra-dation of inosinic acid into inosine and hyposan-thine. Therefore, some chemical index of qualitycan be used.

Color change, weight loss, and rancidity devel-opment can be retarded by freezing, vacuum-packing, and use of low-oxygen permeable films.Careful handling of carcasses at low temperatureslows the disappearance of adenosine triphos-phate and postmortem glycolysis, Storage at hightemperature leads to irreversible toughening.Careful handling also reduces bruising and loss oftissue water (syneresis),

The overall Q 1 0 of deterioration of frozenpoultry is about 20, which is very typical of frozen

Appendix A —Application of Open Dating to Specific Foods ● 63

foods and meats in general. The Q10 for freshpoultry shelf life varies from 2 to 7, depending onthe preprocessing and processing methods used.

The past frequency of foodborne infections thatcan be disseminated by poultry makes the ques-tion of safety relevant. This, however, cannot beprevented by an open date. From a consumerstandpoint, nutrient loss and loss of sensory quali-ty are the most important considerations in set-ting the open date.

Fresh poultry that is cut and prepared in theretail store, is not frozen at any time during itsstorage life, and is not packaged in any containeror wrapping prior to sale could be exempted fromopen dating. The rationale for exemption is thesame as discussed for fresh meat, However, forpoultry that is packaged and/or frozen beforesale, an open date is useful to the consumer.

Pack date. The pack date for most poultry is thedate on which the product is slaughtered, cut up,and put into a package. With a product such aspoultry that has a short shelf life, a pack date—ifdone at retail or in a process center—would be auseful date if it is close to the date of slaughter.However, temperature abuse would lead to an im-proper guess by the consumer as to the quality ofthe product beyond this date.

Sell-by date. The estimation of a sell-by datecould be made by each producer, based on aknowledge of the exact processing conditions andthe normal distribution conditions, including theretail store. The sell-by date would provide somehelp to the consumer, but the exact informationregarding how long after the sell-by date the prod-uct could be used is missing. Coupled with a sell-by date, information on how long the productcould be stored in the home—either frozen or re-frigerated—would be most useful.

Best-if-used-by date. From the producers’standpoint, estimating a sell-by date is almost asdifficult as estimating a use-by date, the only dif-ference being the knowledge of temperature con-ditions under refrigeration and freezing in theconsumer’s home. Theoretically, a best-if-used-bydate would be the most meaningful date for theconsumer. However, based on presently availableinformation on poultry shelf life, it would be dif-ficult to estimate a general sell-by or best-if-used-by date. In addition, home storage temperaturecan vary by 6° and with a high Q10 this could af-fect shelf life. Determining these dates would re-quire considerable money to collect the requiredinformation. In addition, different methods andmore control for the grocery store display of prod-ucts would have to be developed.

Fresh Fish

Modes of deterioration. The major mode ofspoilage for fresh fish is bacterial decompositionon the surface of the fish. Factors affecting thekeeping quality of fish are: 1) environment wherecaught (season, location, bacterial load of water),2) fish species, and 3) handling conditions (tem-perature, sanitation). The same factors apply toshellfish, although since lobsters, clams, andcrabs are sold alive, proper temperature—partic-ularly prevention of any rapid change in tempera-ture—is of paramount importance.

Fresh fish is generally not prepackaged and isalmost always packed and distributed in ice.Maintenance of surface temperatures below 2° Cis of utmost importance. Shelf-life data show thata typical marine (saltwater) fish such as cod has ashelf life of approximately 14 days when storedon ice. The Q10 values of from 4 to 6 indicate theimportance of keeping fish properly chilled, sincea small change in temperature has a drastic ef-fect on an already short shelf life. For example,raising the temperature to 10° C would reduceshelf life to less than 2 days. The Q10’s of growthfor typical spoilage bacteria closely resemble theactual sensory quality data. As with fresh meatand poultry, safety from pathogenic organismscannot be guaranteed by open dating, it is onlypossible by proper sanitation and holding tem-peratures below 7° C.

The detrimental effects of psychotropic bacte-rial growth become evident in fresh fish muchsooner than any nutrient loss or safety hazard oc-curs. Thus, sensory considerations are the limit-ing factors in determining shelf life.

Fresh fish that is prepared in the retail store, isnot frozen at any time in its storage life, and is notpackaged in any container or wrapping prior tosale could be exempted from open dating. The ra-tionale for exemption is the same as discussed forfresh meat. However, for fresh fish that is pack-aged and/or frozen before sale, an open date isuseful to the consumer.

Pack date. In the case of fresh fish, the packdate should be termed the “catch date. ” Thecatch date marks the beginning of deteriorationand must be known in order to set a sell-by or use-by date. However, even with proper temperaturecontrol and sanitary handling, the length of shelflife varies with each species of fish and alsowithin species because of season, location, andbacterial load of the water. Therefore, the catchdate is not technologically useful in setting a shelflife. From a retailer’s and a consumer’s stand-

64 ● Open Shelf-Life Dating of Food

point, the pack date would be most meaningful,since one could easily determine if the fish wereold. Even if it were already packaged, a consumercould then reject it based on experience with oldfish. This is especially true since most consumersbuy fresh fish on or close to the date of consump-tion.

Sell-by date. This date would have to be set bythe fishing company with knowledge of the catchenvironment as well as of the species of fish andthe catch date. Its validity would depend on con-trolled temperature and sanitary conditions dur-ing distribution and retailing, Since most freshfish is handled directly by independent fishermenwith no research resources, presently it would betechnologically impossible to set realistic datesbased on real data. The only thing that could bedone would be to set some average values on theproducts which might in fact deceive the consum-er, especially since abuse may easily occur.

Best-if-used-by date. This date would be nomore useful than a sell-by date for the same rea-sons. Since most consumers buying fresh fish feela need to buy it as close as possible to the actualtime of use, a pack date is more meaningful. Theextreme sensitivity of fresh fish to temperaturesabove 2° to 4° C and to unsanitary handlingwould make retailers very reluctant to initiate ause-by date,

Fresh Fruits and Vegetables

Modes of deterioration. The major modes of de-terioration of fresh fruits and vegetables can beclassified as: I) enzymatic and chemical reactionsleading to nutrient loss as well as loss of sensoryappeal, and 2) microbial decay resulting in loss ofsensory appeal as well as possible health hazardsif pathogenic organisms are present.

Some of the factors affecting the point of onsetand the rates of these various reactions includethe following:

1.

2.

3.

Growing conditions—such as soil and waterconsumption, amount of sunlight, and tem-peratures—that have a direct effect on thechemical composition of fruits and vegeta-bles.The point in the maturation process at whichthe fruit or vegetable is harvested, since itdetermines the degree of maturity and therate of maturity. This effect varies with thetype of fruit or vegetable.The temperature of harvesting and subse-quent storage. The higher the temperature,

4.

5.

6.

the faster the reaction rates (Q10 of 2 to 3),but damage can also occur if held at too lowa temperature (chill injury), which varieswith each fruit and vegetable,Any physical bruising or damage occurringduring harvesting and transportation. Punc-tures and broken skin can allow entry andgrowth of micro-organisms; cell ruptureallows mixing of enzymes and substrateswith subsequent decay reactions.The composition of the storage atmosphere.Addition or removal of ethylene can speed orslow ripening; the ratio of CO2 to oxygen hasa direct effect on the rate of respiration, andlack of humidity can cause wilting,Sanitation conditions. Washing or disinfect-ing reduces microbial loads on the surface;fumigation lowers the extent of insect dam-age.

The combinations of these various factors influ-ence shelf life so radically that it is extremely dif-ficult to predict. From the standpoint of food safe-ty, most pathogens (except for molds) do not growon these products. The presence of mold is easy toidentify visually and can serve as an index for re-jection.

Vitamin C is a relatively unstable vitamin. Itdegrades more quickly than most nutrients, so itsloss can be used as a standard in judging the endof shelf life for foods that are major sources ofvitamin C. However, since consumers cannotmeasure vitamin loss, consumers judge fruits andvegetables by their market quality—appearanceand firmness. Market quality has been found tohave a direct relationship to nutritive quality, mi-crobiological contamination, and/or insect con-tamination. Sensory quality is therefore the pri-mary consideration of the type of open-dating sys-tem,

Fresh fruits and vegetables sold in bulk—notpackaged—could be exempted from open dating.This is because the quality of fruits and vegeta-bles sold in bulk can be determined by sight,touch, and smell before purchase is made. Itwould be very difficult to determine a meaningfulshelf-life date because fruits and vegetables aresubject to varying rates and types of deteriora-tion, including physical deterioration as a func-tion of consumer handling. There would also beproblems in physically placing a date on individ-ual items, and the cost of such a program wouldbe prohibitive.

For packaged fresh fruits and vegetables, con-sumers have more diff icul ty in determiningquality.

Appendix A—Application of Open Dating to Specific Foods ● 65

Pack date. In the case of fresh fruits and vege-tables, the pack date would be the date of harvest.Most consumers in the United States would prob-ably have little knowledge as to when a fruit orvegetable was harvested unless it was in thegrowing season from local markets. In addition,the great influence of the factors discussed aboveon shelf life would make this date inapplicable tofruits and vegetables that can have extendedshelf lives if stored under ideal conditions. How-ever, a harvest date would be of great help in thecase of vegetables that usually are picked at thepeak of quality and have a relatively rapid deteri-oration in quality. Sweet corn on the cob is an ex-ample, but even here, unless the corn is immedi-

ately chilled, it can lose 50 percent of its sweet-ness in several hours, and the date would be no in-dication of quality.

Sell-by date. A sell-by date would be extremelydifficult to predict, implement, or enforce, espe-cially for products with a short shelf life. In anycase, consumer judgment by appearance and tex-ture is more valid and is a built-in means of shelf-life assessment.

Best-if-used-by date. The conclusions for a sell-by date are also true for a best-if-used-by date,unless advances are made to have absolute con-trol over distribution. If such control were possi-ble, a sell-by or best-if-used-by date could be im-plemented.

SEMIPERISHABLE FOODS

As noted earlier, this category is given to foodsthat do not deteriorate very rapidly but, on theother hand, do not last for a long time under nor-mal storage conditions. Perishable foods can bemade semiperishable by better handling and byuse of new technology such as controlled atmos-pheric storage. Long shelf-life foods, if abused,become semiperishable. Thus, the choice of put-ting foods into the semiperishable category ismore subjective than objective.

Fried Snack Foods

Modes of deterioration. Common to all friedsnack foods is fat added as a processing agent. Allfats are subject to deterioration by oxidative andhydrolytic rancidity—the major mode of deteri-oration of all fried snack foods. The more unsatu-rated the fat, the more subject it is to rancidity.

A second mode of deterioration of dry-friedsnack foods is moisture gain. Unacceptable loss ofcrispness occurs when moisture gain reaches awater availability (aw) of 0.4 to 0.5. Hydrolyticrancidity (an enzyme reaction) can be inhibited byhigh-temperature denaturation of the naturallipase enzymes present in most foods, It also is in-hibited by drying to below an aw of 0.2 and at lowtemperature.

Oxidative rancidity has a Q10 of about 1.5 to 2.5.It can be controlled by protecting unsaturatedfats from oxygen, metal ions, light, and high tem-perature, Addition of phenolic-type antioxidantsis one of the most important means of preservingfats. Use of fresh oil in processing also is impor-

tant since the presence of intermediate com-pounds produced accelerates the reaction.

The shelf life of fried snack foods can also beextended by packaging under an inert atmos-phere. Potato chips in cellophane film coated witha moisture barrier have a shelf life of 4 to 6 weeksat 21° C. This can be extended to 6 months bypackaging in a laminated container under nitro-gen gas.

No microbiological safety hazards are pre-sented by average fried snack foods since theirwater activity is low and they would lose crisp-ness before microbes would grow. The end prod-ucts of lipid oxidation have been shown to be toxicin animal studies. However, large amounts of ex-tremely rancid fried foods would have to be con-sumed for a hazard to appear. Likewise, there islittle nutrient loss because of lipid oxidation,since only a small portion of the fat oxidizes. Thusthe primary consideration in determining the endof shelf life is sensory quality.

Pack date. The pack date has the advantageover the other two types of open dates in that itcould be most easily and cheaply implemented.However, the disadvantage of the consumer’slack of knowledge about shelf life is compoundedin this case by the fact that processing conditions(temperature, moisture content, use of fresh oil,and antioxidants) and packaging effectiveness(type of moisture, light barrier, and headspacegas) are crucial in determining the length of shelflife. Since these factors are different for eachproduct, shelf life must be determined individual-ly for each product. Therefore, a pack date is notmeaningful except to help in stock rotation.

66 . open Shelf-Life Dating of Food

Sell-by date. The sell-by date could be a mean-ingful date for fried snack foods if the date werebased on meaningful data as to quality changes inrelationship to the environmental and initial oilcharacteristics, Companies could, based on typi-cal ingredients, develop tests to measure shelflife. However, a range would be needed, since dis-tribution conditions could vary, The date wouldbest be accompanied by some meaningful home-storage information such as “store in a cool, dryplace” or “store away from home appliances andin a cupboard. ”

Best-if-used-by date. This date for fried snackfoods would be relevant under the same condi-tions as a sell-by date. It would probably be mostrelevant if accompanied by recommendations forhome storage. Abuse conditions, however, couldoccur that would lead to loss of quality before theend of shelf life.

Cheese

Modes of deterioration. Modes of deteriorationfor cheese include: 1) undesirable microbialgrowth resulting in visible surface-mold colonies,slime, putrefaction, or gas formation; 2) moistureloss; 3) chemical reactions such as nonenzymaticbrowning, lipid oxidation; and 4) lactose crystal-lization, In properly packaged, unopened cheese,surface mold or slime formation and moisture lossshould not occur.

In processed cheese, chemical reactions arethe major deteriorative modes, while in naturalcheese, both undesirable microbial growth andchemical reactions lead to deterioration.

The shelf life of processed cheese stored at 4°C is generally about 4 months to 1 to 2 years.Natural cheese stored at 0° to 2° C has a shelf liferanging from 4 to 12 months, The Q10 for lipid ox-idation is low, about 2, whereas for nonenzymaticbrowning, it is about 5. The Q10 for microbialgrowth is generally 6 to 8, so that temperatureabuse will generally lead to microbial activitycausing the end of shelf life. It should be notedthat some browning is desirable as it leads toflavor development, and thus some cheese im-proves in quality with aging.

Cheese is susceptible to pathogenic growth, no-tably Staphylococcus aureus. However, con-tamination with pathogenic organisms only oc-curs if poor sanitary conditions occur duringprocessing. The organism cannot grow below 7°C. Pathogenic growth does not correlate to shelf

life, however. Also, since nutrient loss occursvery slowly after the initial processing proce-dures, it does not determine shelf life. Sensoryquality changes from undesirable microbialgrowth and chemical reactions, therefore, are theprimary factors in determining the end of shelflife.

Pack date. Since most consumers do not haveknowledge of the shelf lives of cheese (and theyvary considerably), a pack date is not beneficialexcept: 1) to ensure rotation and 2) for thosecheeses that improve in quality as they age.

Sell-by date. Since most consumers storecheese under refrigeration, a sell-by date couldbe a meaningful way of open dating some cheesesthat have a relatively short shelf life (1 to 6months). For cheese of longer shelf life, it is prob-ably not as meaningful as a use-by date. Ofcourse, this means that distribution temperaturesmust be adequately controlled.

Best-if-used-by date. For cheeses with a longshelf life that are kept under adequate refrigera-tion, a use-by date based on good laboratory datawould be a meaningful method of dating. Thiswould also facilitate stock rotation.

Ice Cream

Modes of deterioration. One primary mode ofdeterioration of ice cream is the development of agrainy texture caused by crystallization of lactoseunder fluctuating temperature conditions as a re-sult of the automatic defrost cycles of most freez-ers, Flavor deterioration caused by fat oxidationand hydrolysis becomes important during long-term storage,

Sensory quality as measured by adverse tex-ture is the limiting factor in determining shelf life.Safety hazards or nutrient losses are not of im-portance since these would occur only if the icecream were thawed, and the product would thenbe texturally inedible.

Pack date. The pack date would be the easiestdate to implement, but differences in temperaturecycles in different distribution systems far out-weigh the relevance of the pack date. It wouldhelp to facilitate turnover, however,

Sell-by date. This date could be determinedwith knowledge and control of the temperature-time conditions encountered in the distributionsystem. It would be the most useful date to theconsumer, since most ice cream is consumedwithin a relatively short time after purchase.

Appendix A—Application of Open Dating to Specific Foods ● 67

Best-if-used-by date. Determining this date ket. It would therefore not serve a meaningfulwould be very difficult, given the uncertainty of purpose.temperature cycling after purchase from the mar-

LONG SHELF-LIFE FOODS

Some foods have been classified by variousState governments as being nonperishable andthus not subject to open dating. In fact, somemanufacturers suggest their products have an in-definite shelf life. As pointed out in this report, allfoods deteriorate as a function of the environmen-tal conditions. Open dating of foods with a longshelf life may be the most meaningful of any foodperishability category because these foods mayremain on the shelf for a fairly long time bothbefore and after purchase. Some type of datewould help to ensure proper rotation and give theconsumer an index of when the food should beused,

Dehydrated Foods

Modes of deterioration. In general, the majormodes of deterioration for dried foods include:1) loss of nutrients, especially vitamins C, B1, andlysine; 2) nonenzymatic browning; 3) lipid oxida-tion; 4) pigment degradation; and 5) moisture gainto a critical level that causes sogginess, To ensureagainst these problems, drying to a specific pro-tective moisture value is critical along with a goodwater-impermeable pouch to prevent gain, Thepouch should be vacuum-sealed or gas-flushed,and should be opaque.

For all dehydrated foods, the moisture contenthas a great effect on the rate of the deteriorativereactions and also on the sensitivity of the rates toan increase in temperature. For example, therates of loss of water-soluble vitamins, nonenzy-matic browning, and chlorophyll degradation in-crease with increased moisture content, Overdry-ing causes an increase in the rate of lipid oxi-dat ion and increases the loss of carotenoidpigments and fat-soluble vitamins. For some reac-tions, an increased moisture content increasesthe Q10, while in other reactions, the Q 10 i slowered. Protection from oxygen can slow oxida-tion reactions, but the cost of oxygen-excludingpackaging must be balanced with the practicalityof adding antioxidants.

A knowledge of the types of deteriorative reac-tions in each product, their rates, and how these

rates change with temperature, moisture content,packaging, oxygen availability, and other proc-essing parameters is necessary to determine theshelf life of any dehydrated food, Hence, shelf lifemust be determined separately for each individ-ual product.

In general, the shelf lives of dehydrated vegeta-bles at 210 C vary from as low as 2 or 3 months toas much as 12 or 15 months. Similarly, meat shelflife can vary from 1 to 6 months, and dried fruitsfrom 1 month to 2 years, depending on the aboveconditions. The Q 10 for these reactions rangesfrom 2 to over 10.

Safety hazards from microbes are generally nota consideration in determining the shelf lives ofdehydrated foods if they are protected from mois-ture gain. The only microbial growth that can oc-cur is that of xerophilic yeasts and molds that cangrow at water activities from 0.6 to 0.7. Thisgrowth is generally slow and not of a pathogenicnature and would be easily recognized. Nutrientlosses occur through lipid and vitamin oxidationsand through loss of essential amino acids duringnonenzymatic browning. These have a Q10 of from2 to 6. Sensory quality losses occur through colorlosses (Q10 = 2), nonenzymatic browning leadingto darkening and hardening (Q10 = 4 to 6), andlipid oxidation (Q10 = 1.5 to 2) resulting in rancidi-ty. Thus both nutrient loss and sensory qualitychange must be considered, the shelf life beingl imited by whichever becomes unacceptablesooner , based on some s tandard set for thechange in the specific reaction allowable.

Pack date. With respect to dehydrated foods, amyriad of reactions can occur that are a functionof initial quality and processing conditions andthat are influenced by temperature, moisturechange, oxygen level, light, and package permea-bility. Since consumers are unaware of these fac-tors, a pack date would seem useful only from thestandpoint of stock rotation.

Sell-by date. To implement a sell-by date, amanufacturer must assess the major mode of de-terioration of a particular product and gather in-formation on the distribution system. From this,an average sell-by date could be instituted. If an

68 ● Open Shelf-Life Dating of Food

estimated shelf life after the sell-by date wereestablished for various environmental combina-tions of temperature and humidity in the home,the product could be offered for sale after thesell-by date at a reduced price. Although a sell-bydate is a reasonable type of open dating for dehy-drated foods, some type of system that would giveestimated shelf life for the food beyond the dateshould be included. This information could, ofcourse, depend on the area of the country.

Best-if-used-by date. The interaction of the ef-fects of environmental conditions illustrated inthe above discussion and the fact that significantbut condition-variable shelf life is left after thedate of sale could make this date inapplicable todehydrated foods unless it was based on the prod-uct being sold and consumed in specific areas ofthe country.

Nonfat Dry Milk

Modes of deterioration. Nonenzymatic brown-ing, resulting in loss of protein nutritional value,and flavor deterioration are the major deteriora-tion modes of nonfat dry milk, The Q10 of nonen-zymatic browning varies from 2.3 to 3, increasingas relative humidity rises, The Q10’s for flavordeterioration range from 2 to 16, increasing withrising moisture content. The shelf life of nonfatdry milk under normal storage conditions isaround 1 year.

Under normal storage conditions, safety is nota consideration in setting the shelf life of nonfatdry milk, unless it was previously contaminated.Nutrient loss should probably be the major con-sideration in shelf life. Studies have shown thatflavor change occurs but is not as significant asnutrient loss.

Pack date. The pack date could be most easilyimplemented for dry milk on the date of manufac-ture. However, the dependence of shelf life on ini-tial moisture content lessens the usefulness of thepack date without an industrywide standard forinitial moisture, Lack of consumer knowledge ofshelf life is always a disadvantage in using a packdate, especially for long shelf-life foods.

Sell-by date. The sell-by date could be deter-mined given a basic knowledge of initial moisturecontent, package permeability, and temperature/humidity conditions of distribution, Generally, asell-by date is not as useful to consumers as a use-by date since it does not define the amount of timeleft for home storage, but it conveys more infor-mation than a pack date. If average home storage

times were indicated, the sell-by date would beuseful,

Best-if-used-by date. Given the sensitivity to ex-ternal relative humidity and thus moisture con-tent of nonfat dry milk deteriorative reactionrates, this date may be difficult to determine.Moisture gain after the package is opened wouldvary greatly with humidity conditions and couldbe the determining factor in shortening shelf life.Obviously, moisture gain would not be a problemwith a small package that is used rapidly, butwould be a problem with slowly used packages.Therefore, shelf life should be a criterion of thesealed pouch and not include time after opening,A best-if-used-by date could be set if all the sameinformation as in a sell-by date were known.

Breakfast Cereals

Modes of deterioration. The shelf life of mostready-to-eat dry breakfast cereals is 6 to 1 8months at ambient temperatures assuming pack-age integrity based on industry estimates. Themodes of deterioration include: 1) moisture gainresulting in loss of crispness, 2) lipid oxidationresulting in rancidity, 3) vitamin degradation re-sulting in loss of nutritional value, and 4) break-age resulting in esthetic undesirability.

Proper packaging can keep the moisture gainbelow the critical value of 2 to 3 percent and canminimize breakage. Turnover of most cereals usu-ally occurs before any significant vitamin loss,since vitamin degradation proceeds very slowly.Vitamin A loss, under dry conditions, is the mostrapid, but is still small. Thiamin and riboflavinloss become important only if abused at high tem-peratures.

Lipid oxidation is the major mode of deteriora-tion most often resulting in the end of shelf lifebecause: I) cereals are dried to the monolayermoisture value or below inhibiting other modes ofdeterioration and 2) cereal grains have a highratio of unsaturated fats that promotes oxidation.The Q10 of lipid oxidation in cereals is less than 2,As a consequence of this low Q10 the potential fortemperature abuse with respect to flavor is alsolow. Antioxidants, added to the flakes by sprayingor to the package liner, extend shelf life but do notaffect the Q10.

No safety hazards are presented by over-agecereals under normal conditions, and there is lit-tle nutrient loss at the point of detectable rancidi-ty. Sensory quality is thus the primary considera-tion in limiting shelf life.

Appendix A—Application of Open Dating to Specific Foods ● 69

Pack date. The use of a pack date would be ad-vantageous in that it would be little different fromthe present system. Coded pack dates are present-ly placed on most cereal package overwraps, ifnot on each individual container. The majorchange would be to an uncoded date. If a packdate is used, there is no necessity of settingcriteria concerning the quality of the product orfor analysis of the modes and rates of deteriora-tion. Cost of implementing the use of a pack datewould be minimal and yet the open date wouldbetter facilitate stock rotation than would thecoded date.

A disadvantage, however, would be the possi-bility of consumers confusing the pack date with asell-by or use-by date and thus believing all theproducts to be over-age. The obvious disadvan-tage of a pack date is the lack of any informationabout the expected length of the high-quality lifeof the cereal—a life that varies more among thedifferent cereal types than many consumerswould expect. Consumers also may expect ashorter life in general than is actually the case,which could result in unnecessary waste. Thepack date does have a consumer advantage inthat it in no way imposes manufacturers’ judg-ment about the “staying power” of product quali-ty. Consumers are left to make their own judg-ment.

Sell-by date. A sell-by date has the advantageof giving consumers some idea of how long to ex-pect high quality. It would always be a future datein the market so that there would be little roomfor confusion, and it is easily policed by retailersand consumers alike. A sell-by date is not a finaldate for use, so it leaves open the possibility of theretailer selling the product after the date if theretailer clearly informs the consumer that thesell-by date is past. The Q10’s of cereal deteriora-tion are so low that temperature variations do nothave an extreme effect on the rate of deteriora-tion unless a cereal is held for long times at hightemperatures. Therefore, the time at which dete-rioration may become noticeable to the consumercan be adequately predicted over a fairly broadtemperature range.

The disadvantages of a sell-by date include thefact that consumers may not know how long theycan expect to store the product at home beforeusing it, especially if they do not know properstorage conditions. The other side of this disad-vantage is that a sell-by date alone does not giveconsumers the date of manufacture, so they mustrely on the manufacturer’s judgment of shelf life.

In addition, temperature is still an important fac-tor, so the end of shelf life would have to beunderestimated to allow for possible temperatureabuse, possibly resulting in the waste of someproduct if turnover rates were slow enough.

Best-if-used-by date. This date could be advan-tageous because it gives the consumer the bestidea of the actual length of high-quality life. Itsuse can be considered for cereals because of thelow Q10. However, it should be accompanied withrecommendations for storage conditions, sincelong-time abuse of high temperature would invali-date the date,

The major disadvantage of a best-if-used-bydate over a pack or sell-by date would be that itrequires the most accurate knowledge of distribu-tion conditions and deteriorative reaction ratesunder these conditions. It should not result inmuch product waste because the shelf life ofcereals is long compared with the turnover time,but it could result in some consumer objection tothe length of the manufacturer’s estimate of shelflife, especially at the beginning of implementa-tion.

Pasta

Modes of deterioration. The shelf life of pastaproducts with egg solids added is generally recog-nized to be 9 months to 3 years, and that of maca-roni and spaghetti to be 2 to 4 years. The modes ofdeterioration include: 1) moisture gain or loss, 2)loss of carotene pigment in the egg solids, 3) ab-sorption of flavors from the package, 4) “staling”probably caused by lipid oxidation, 5) loss of Bvitamins, and 6) loss of protein quality in enrichedproducts.

Little or no information is available in the U.S.literature concerning rates of pigment loss orflavor deterioration in pasta.

Pasta with a moisture content below 6 percentis too fragile, and above 13- to 16-percent mois-ture content, both mold growth and starch retro-gradation, which cause toughness when cooked,occur. Moisture gain or loss has been found tohave a Q10 of 2.6 to 4.9, much higher than that oflipid oxidation (1.5 to 2.0). The loss of proteinquality has a Q10 of 4 to 6.

Loss of B vitamins occurs very slowly in opaquepackages, but when exposed to light. 50 percentof the riboflavin and pyridoxine content can belost in 19 and 62 days, respectively. This vitaminloss has not been adequately considered in shelf-life studies and is not reflected in the shelf livesgiven above. No Q10 data are available.

70 Ž Open Shelf-Life Dating of Food

No microbiological safety hazards can occurwith over-age pasta under normal conditions.There is some evidence that nutrient losses mayoccur primarily because of vitamin B degradationin nonopaque packages. More information isneeded, however, before nutrient loss can be usedto set shelf life. Loss of sensory quality caused bytoughening or flavor change is at present the pri-mary consideration in determining shelf life,

Because the Q10 of the sensory changes is low,the advantages and disadvantages of each type ofopen dating are very similar to those previouslydescribed in the section on breakfast cereals.

Pack date. A pack date would be most easilyand cheaply implemented, since it would simplymean uncoding dates already used. It involves nojudgment of quality criteria and is simply a fac-tual date. The disadvantage of using it includesthe possibility that distribution times of pastaproducts of 1 to 2 months may lead consumers toobject to a perceived lack of freshness, Consum-ers would need a knowledge of the actual shelflife in order to adequately use a pack date.

Sell-by date. The low Q10 of most deteriorativereactions found for pasta products means that adate could be set that would be very representa-tive of products distributed within a fairly broadtemperature range, However, if the pasta were toserve as a protein source in the diet, the high Q10

for nonenzymatic browning could lead to furtherdeterioration if the product were abused. Muchmore data is needed on actual distribution times,temperatures, and humidities, and on the deteri-orative reaction rates under these conditions tobe able to set a sell-by date. The length of time ofacceptable quality remaining after the sell-bydate would have to be standardized, and consum-ers would have to be informed of this and of prop-er storage conditions.

Best-if-used-by date. This date gives consumersthe best idea of the manufacturers’ judgment ofthe shelf life of the product. However, it requiresthe most accurate knowledge of distribution con-ditions and deteriorative reactions.

Concentrated Juices

Modes of deterioration. Frozen and cannedconcentrated juices can deteriorate by: 1) nutri-ent loss, primarily vitamins C or A; 2) microbialgrowth, primarily caused by yeasts and molds;3) loss of color and flavor; and 4) loss of turbidityor cloudiness through enzyme reactions.

Vitamin loss tends to be very slow in concen-

trated juices. Frozen concentrated citrus juicesretain 90 to 97 percent of their vitamin C for 1year at temperatures as high as 0° C. Cannedpineapple, tomato, and carrot juice may be storedat 10° to 15° C with minimal loss of vitamins Aand C for 2 years.

The low pH of juices prohibits microbial growthother than yeasts and molds. Microbial growth oc-curs in two cases: 1) if the frozen juices areabused by holding above freezing temperatures or2) after the cans are opened. Color and flavorchanges occur to the greatest extent in concen-trated frozen juices, mainly because of heat treat-ments needed to inactivate enzymes. New meth-ods of high-temperature, short-time (HTST) pas-teurization and canning procedures, coupled withthe addition of aroma concentrate, have madegreater color and flavor retention possible. Innonpasteurized concentrated juices , loss ofcloudiness and turbidity are the primary limits toshelf life, With inactivation of the enzyme pectinmethylestenase by HTST pasteurization, how-ever, cloud stability has been significantly in-creased.

The shelf life of frozen concentrated fruit juicesof – 18° C varies from 18 to 30 months, dependingon the type of fruit. The Q10’s for sensory qualitylosses of frozen fruit juices vary from 2 to 8. TheQ 10’s for vitamin loss are less than 2. Of concern isthe long storage of bulk product from a bumperyear for sale the next year.

Open-dating considerations for frozen juicesare very similar to those for frozen fruits andvegetables, with the exception that vitamin dete-rioration does not occur before sensory qualitydefects. Safety hazards from pathogenic orga-nisms should not be of concern because of the lowpH of the product.

Pack date. Since the shelf life of different juicesvaries significantly, a pack date may not be mean-ingful to the consumer. Pack dates, however,would help in maintaining stock rotation butwould create problems if the juice is packed fromthe previous year’s bulk storage.

Sell-by date. The sell-by date for concentratedjuices would be of advantage if distribution condi-tions were known and abuse—especially for fro-zen products— were prevented. Some allowancewould have to be made for excess products pro-duced in bumper crop years and held into a sec-ond year to ensure against quality loss. A sell-bydate with information as to months of high qualityleft in frozen or canned home storage would bebeneficial.

Appendix A—Application of Open Dating to Specific Foods ● 71

Best-if-used-by date. This would be the bestform of dating if adequate knowledge of storageconditions could be obtained. However, abuse—especially in the home—could shorten shelf lifesignificantly.

Frozen Fruits and Vegetables

Modes of deterioration. The mode leading toloss of quality and nutritional value during stor-age of frozen fruits and vegetables is very depend-ent on the type of product, its initial quality, andthe freezing conditions. Microbiological growthand spoilage should not be a problem if the prod-uct is stored below the freezing point, In fact, themicrobial population will gradually decline dur-ing subfreezing storage, However, abuse can leadto growth, but it should not be significant withrespect to pathogens.

The types of changes that can cause loss of sen-sory quality and nutritive value during storage offrozen produce include: 1) pigment loss, 2) ascor-bic acid oxidation, 3) off-flavor developmentcaused by either lipid autoxidation or browning,4) loss of the characteristic flavor notes, 5) weightloss, 6) package ice formation, and 7) cellular andstructure breakdown (loss of final crispness). Theeffects of desiccation because of a highly permea-ble package can cause a loss of up to as much asone-fifth of the weight over a storage period of 1year at – 18° C. This will result in evidentchanges in appearance but has little or no effecton palatabi l i ty or loss of ascorbic acid orcarotene. Under longer storage, surface dehydra-tion can advance to a stage where objectionablecolor and textural changes, as well as a dry ap-pearance, are developed.

The shelf life of frozen fruits and vegetablescan vary from 6 months to 2 years, depending onthe product and on the quality aspect measured.Also, the temperature coefficients of the qualitylosses vary from 2 to 40. Thus, deteriorative reac-tions with greater temperature sensitivities maydominate at higher temperatures and be insignifi-cant at lower temperatures. The high sensitivity,however, indicates that good temperature controlis necessary.

A hazard due to pathogens can occur from fro-zen fruits and vegetables only if the microbes arefrozen with the initial product (a processing fail-ure), survive the freezing, and then thawing oc-curs so that the pathogens can grow (a handlingfailure). These events are rare enough that theyare not open-dating considerations.

However, nutritive value is another matter.

Frozen fruits and vegetables are consumed forpleasure and as a major dietary source of vita-mins and minerals. In some cases, vitamin contentmay fall below some accepted standard beforesensory quality becomes inadequate. Therefore,if vitamin content is used as the primary open-dating consideration, provisions should be madefor the continued sale of over-age frozen fruitsand vegetables up to the point of actual unpalat-ability y.

Pack date. Because the shelf life of frozen fruitsand vegetables varies from 6 months to 2 years,the pack date may be the easiest to implement.However, it would not tell the consumer anythingabout the shelf life of the product. The problem ofseasonal packing and of overabundant crops in I

year could be a very difficult problem, since itcould lead to wasting good products.

An extensive educat ion program, perhapscoupled with a system similar to the British“three-star” system, could make the sell-by datebeneficial. Under the British three-star system,home storage life for different temperatures isdefined on the package. Freezer units are ratedon their ability to maintain certain temperatures( -6°, -12°, and -18° C), and based on the tem-perature, receive a one- ( k), two- ( A A), or three-( k + k) star rating. Product packages are labeledwith recommended storage times (either from thepack date or after a sell-by date) for each of thestar ratings. As with other foods, the pack datedoes facilitate stock rotation.

Sell-by date. The sell-by date could be imple-mented without a home freezer-rating system. Thelast date of sale could be determined with aknowledge of initial product quality distributiontimes and temperatures and rates of deteriorativereactions at these temperatures, However, col-lecting this data could be expensive.

A sell-by date, coupled with the home-storagesystem mentioned above, would be very beneficialand would eliminate the possible wastage prob-lem from years of high crop production. This sys-tem would also facilitate rotation,

Best-if-used-by date. The high Q10 of some of thedeteriorative reactions of frozen fruits and vege-tables, together with the uncertainty of home-stor-age temperature conditions make implementationof a definite use- by date difficult. Also, a definiteuse-by date may be impractical, since surveyshave shown that a major portion of frozen fruitand vegetable deterioration occurs with the enduser. The optimum date would be a best-if-used-bydate, since it is most appropriate for a food with

72 . Open She/f-Life Dating of Food

long shelf life under controlled conditions andwith some estimate of home storage.

Frozen Meats and Fish

Modes of deterioration. Lipid oxidation andprotein denaturation are the major modes of dete-rioration in both frozen meats and frozen fish,However, they occur more rapidly in frozen fishbecause of the greater ratio of unsaturated tosaturated fats and the higher percentage of myo-fribular proteins that become insoluble with stor-age. Tissue desiccation and myoglobin colorchanges also occur with extended frozen storage.

Antioxidants have not been successfully ap-plied for increasing shelf life of frozen meat andfish. Glazing with various solutions of phosphates,sugars, monosodium glutamate (MSG), benzoicacid, and polyhydric and other alcohols, if al-lowed, can be used in place of the more expensivewrap-packaging. Effective packaging increasesshelf life and overall product quality by protect-ing from excessive dehydration, denaturation,oxidative rancidity, and microbial recontamina-tion.

At – 18° C, the shelf life of fish varies from 2 to8 months, depending mainly on the species, withQ 10’s varying from 1.5 to 4,5. Frozen shellfish gen-erally have a shelf life at – 8° C of 2 to 4 months,with the exception of 10 months for crab. Frozenbeef, pork, veal, and lamb at - 18° C have shelflives of about 6 to 12 months, 4 to 12 months, 4 to14 months, and 6 to 16 months, respectively, withQ10’s of about 2.

The biggest problem is abuse by holding justbelow the freezing point. Under those conditions,excessive deterioration could occur. A freeze-thaw indicator with the right melting point couldindicate whether this has occurred.

Microbial deterioration with possible patho-genic growth is not a major mode of deteriorationin frozen meats and fish, since freezing tempera-tures inhibit activity of most microbes. Safetyhazards are therefore not a consideration in opendating unless the product is abused and storedabove freezing. Even then, spoilage organismsusually grow faster than the pathogens.

Nutrients in frozen meats are generally wellpreserved. Thiamin, riboflavin, and niacin haveshown changes upon freezer storage, but no rela-tionship between these changes and storage tem-perature have been seem The nutrient losses areinsignificant and are not a good measure of shelflife in frozen meats and fish, Flavor deterioration

caused by oxidation of fats is usually the primarylimiter of shelf life.

Pack date. The date of packaging is useful in in-dicating production and facilitating stock rota-tion. However, since the shelf life is very species-dependent and consumers have little knowledgeof shelf life, it is not a feasible system.

Sell-by date. A sell-by date for frozen meat andfish, using the same system as for frozen fruitsand vegetables, would be of benefit to the consum-er. The major problem would be abuse—especial-ly holding just below the freezing point—whichwould deteriorate the product much sooner thanexpected.

Best-if-used-by date. As with frozen fruits andvegetables, the same information to set a sell-bydate can be used to set a best-if-used-by date ifadequate knowledge of home-storage conditions isavailable.

Frozen Convenience Foods

Modes of deterioration. Frozen conveniencefoods are precooked meat, vegetable, and pastaproducts packaged separately or in combination.Reheating in a tray is all that is usually necessarybefore consumption.

The predominant mode of deterioration of pre-cooked frozen foods is lipid oxidation, causingrancidity in the meat portion of the product. How-ever, the susceptibility of the product to lipid oxi-dation is strongly influenced by ingredients, proc-essing, and packaging that go into making theproduct.

Changes in gravies and sauces (weeping andcurdling) is the other major deteriorative mecha-nism. Note, however, that most of the literature onthese convenience foods is more than 10 yearsold, and thus this may not necessarily be the ma-jor modes of deterioration of today’s products(that is, few TV dinners or frozen precooked en-tree products list antioxidants as ingredients).

The shelf life of frozen precooked chicken, beef,and pork entrees with no sauce or gravy rangesfrom 6 to 12 months. With sauces and gravies act-ing as an oxygen barrier, the shelf life can be in-creased by over 400 percent. The Q10's range from2 to 3.5 in the – 23° to – 29° C temperaturerange.

The shelf lives of the sauces and gravies aresimilar to those for meats, with a Q10 of up to 30.

In considering modes of deterioration, freezerstorage at or below – 18° C has been assumed,although it is not always the case. At these tem-

Appendix A—Application of Open Dating to Specific Foods ● 73

peratures, microbial growth is not a problem. Pre-cooked frozen foods pose no real health hazardeven if eaten when rancid—unless the productthaws out and is held at above 7° C, allowingpathogens to grow in the sauces. Adequate pro-tection such as a freeze-thaw indicator would beneeded to guarantee safety.

Nutrient losses may occur, but the great varietyof ingredients, ingredient history, and packagingcombinat ions that ul t imately appear in thefreezer case make generalizations difficult. Sen-sory quality changes are the most readily ap-parent and are the mode of deterioration m o s toften reported in the literature. However, withthe institution of open dating and further studyinto each product, it may be found that nutrientlosses should actually be used as an indicatingchemical factor to predict the end of shelf life ofsome frozen convenience foods,

Pack date. The great variation in ingredients,processing, and packaging of precooked frozenfoods, resulting in a great variation in shelf lives,makes the pack date relatively useless to the con-sumer who cannot be cognizant of all variations.A legible pack date would aid in first-in, first-outstock rotation but may result in inappropriatepurchasing patterns because of misconceptionsabout shelf lives.

Sell-by date. Given assurance of a temperaturerange of – 18° C or below in distribution condi-tions, this date could be determined by producersfor each of their individual products. It would beespecially useful to the consumer if coupled withlabel information concerning appropriate lengthof storage in different types of home freezers asdiscussed for other frozen foods. Even withoutthis information, however, the sell-by date wouldbe of more use to the consumer than would a packdate.

Best-if-used-by date. If the uncertainty of thefrozen distribution system could be removed byassuring that some maximum time/temperatureexposure would not be exceeded, a best-if-used-bydate would seem to be most appropriate, as withother frozen foods.

Canned Fruits and Vegetables

Modes of deterioration. Components of cannedfruits and vegetables deteriorate as a function oftemperature in the following order: 1) flavor, 2)color, 3) texture, and 4) nutritive losses.

Changes in flavor in canned fruits and vegeta-bles during storage can be caused by browning

reactions, staling, and loss of flavor (flat taste).Browning reactions result in burned and bitterflavors, especially in fruits canned in syrups, andto some extent in sweet potatoes. Many vegeta-bles get a “musty” taste, which could be de-scribed as “old. ” Products high in starch becomestale tasting as staling of the starch occurs. Thisreaction can be accompanied by yellowing.Changes in color during storage include fading ofboth chlorophyll and carotenoid pigments in redand green vegetables. Fruit and starchy vegeta-bles generally turn dark, or brown, in color.

Changes in texture during storage include soft-ening of some vegetables when stored at high tem-peratures. Extremely low temperatures can breakdown the texture of many vegetables, especiallypotatoes, beans, squash, greens, peas, and toma-toes. Other textural changes include a tendencytowards lumping or clumping in beans and peas.

Loss of vitamins tends to occur more slowlythan changes in flavor, color, and texture. Caro-tene and vitamin A are generally at least as stableas the overall quality of a given product. How-ever, thiamin and ascorbic acid may or may notremain at acceptable levels, depending on theproduct, when compared with overall sensoryquality.

Containers used for canned fruits and vegeta-bles also deteriorate during storage. Corrosiveproducts such as fruits tend to have shorter shelflives than bland vegetables because of a morerapid deterioration of the can interior surface.Also, in rare cases, slight imperfections in thedouble seams of cans lead to a loss of vacuum dur-ing long-term storage. Storage at extremely lowtemperatures can lead to damage of can seamsand subsequent loss of vacuum.

The shelf life of canned fruits and vegetablesranges from 1 to probably 3 years, depending onthe product and on the quality aspect being meas-ured. The Q10's of the deteriorative reactions areall quite low, from 1.5 to 2.5, indicating that theend of shelf life can be predicted over a fairlybroad temperature range. Moisture gain or lossshould not occur through the can wall, and oxida-tive reactions should be minimal,

A microbial hazard from Clostridium botulinumin canned fruits and vegetables is the result ofprocessing failures and is not of importance inopen dating, Most often, sensory quality defectsoccur more quickly than vitamin or other nutrientlosses. However, thiamin and vitamin C losses dooccur more quickly in some canned fruits andvegetables. It has been suggested that acceptable

49-394 0 - 79 - 6

74 . Open Shelf-Life Dating of Food

levels of these vitamins should be used as theshelf-life basis for canned foods that are signifi-cant sources of these vitamins in the list.

Pack date. According to the National FoodProcessors Association, the date of pack would bethe easiest to implement but would not tell theconsumer anything about the shelf life of theproduct. Canners who have seasonal packs wouldbe in a difficult position because the date on thecans would seem old when the product is actuallystill well within the shelf life for the product. Thiswould be especially true in years when an over-abundant crop would force the canner to sellsome product the following year. Since the can-ning industry usually figures that a 3-year shelflife for most fruits and vegetables is the norm, a 1-year delay would still result in a more-than-ade-quate shelf life for a given product. However, theconsumer would have to be convinced of this fact.This would take much time, effort, and money.There is also. some chance for confusion amongconsumers who could mistake the pack date for ause-by date.

Sell-by date. This date is not really applicableto cans that are often stored in the home for somelong period of time after being sold. However, ifsome system that indicates shelf life beyond theselling date were indicated, this would be feasi-ble. It would not account for abuse, however.

Best-if-used-by date. This date could be usefulto consumers because it would give an idea of theshelf life of the product if conditions of storagewere known. This would also be useful for rotat-ing stock at the grocery level. However, with allsuch dating, the actual end of shelf life wouldvary with processing, distribution, and home-stor-age conditions. Probably the most useful way topresent this information would be to give label in-formation of shelf life at several temperatures,but it is doubtful at the present time that there issufficient good data for this format. However,since there is data for products at ambient condi-tions, a single date could be embossed on the canwith an explanation of the storage temperatureon which it is based, The canning industry couldcollect data on each product for each mode ofdeterioration, estimate time/temperature dis-tributions, and then estimate the shelf life left atseveral home-storage conditions.

Coffee and Tea

Modes of deterioration. Staling is the majormode of deterioration of ground roast coffee. In-creased humidity increases the rate of staling,

Moisture can cause hydrolysis of the esters,acetals, and ketals in coffee aroma to compoundswith less-pleasing aromas. Staling is thought to becaused by loss of flavor volatiles or by chemicalchanges in the volatile components caused bymoisture and oxygen absorption. The aroma de-generation is defined as changing from flat to oldto sharply rancid, with a cocoa odor in the ad-vanced stages. Flavor concurrently changes fromflat to bitter, old, and rancid. Unprotected groundroast coffee borders on unsalability in 1 to 2weeks, depending on the relative humidity.

The shelf life of ground roast coffee packagedunder vacuum in metal cans depends largely onthe efficiency with which oxygen is removed, Inorder to ensure the greatest product stability, it isnecessary to have no residual oxygen in the can.The difference between 27 “in” of mercuryvacuum and 29 “in” is significant, Nine months’shelf life is an acceptable industry average,

Instant coffee also loses flavor and stales dur-ing storage. Freeze-dried coffee has a longer shelflife than spray-dried coffee. This extended shelflife is largely because of the lower moisture con-tent (2 percent) of the lyophilized coffee comparedwith 4.5-percent moisture content of the spray-dried.

In addition to flavor loss, instant coffee has theproblem of caking because of moisture absorptionwhen it is exposed to the atmosphere. Isothermsshow that the moisture content of instant coffeerises rapidly when it is exposed to increasingrelative humidities (RH). At 50-percent RH, in-stant coffee begins to agglomerate, and above 75-percent RH, it will turn into a liquid. The shelf lifeof unopened instant coffee varies from 18 to 36months, depending on the type of package. TheQ10’s for coffee staling and moisture absorptionare quite low, 1.5 to 2,0,

Tea is preserved by its low moisture content,which inhibits growth of micro-organisms. Duringstorage, tea may undergo staling or lose some ofits aroma. Sometimes foreign or incompatibleodors may be absorbed, Moisture absorption re-sults in caking of instant tea but occurs only if thejar is opened. Black leaf tea and packaged instanttea have a shelf life of about 18 months at 21° C,with a very low sensitivity to changes in tempera-ture, Changes in humidity are more importantconsiderations in the shelf life of tea, especiallytea bags packaged in boxes.

No microbiological hazards are presented byover-age coffee or tea, They do not provide a sig-nificant source of nutrients in the diet, so nutrient

Appendix A—Application of Open Dating to Specific Foods ● 75

loss is not a consideration. Loss of sensory qual-ities is the major open-dating consideration.

Pack date. The date of manufacture would notbe advantageous to the consumer because itwould not provide any information about the shelflife of the product. In fact, an open date of manu-facture might result in considerable wastage,since the consumer might conclude that an olderproduct is not as good as a newer one and wouldbuy the product with the latest date on it. Thisconclusion would be particularly erroneous in thecase of ground roast coffee, since the greatestconsumption of shelf life occurs after the productis opened.

The date of manufacture also does not give anyindication of the true age of the coffee or tea,since the green coffee beans or tea leaves couldvary in age considerably from the time they wereharvested until they were processed and pack-aged. The date would also not reflect any differ-ences in shelf life caused by different processingprocedures among manufacturers.

For example, two manufacturers of groundroast coffee may package on the same day andhave the same date of manufacture. One manu-facturer, however, evacuates the cans to 29 “in”of mercury and thereby rids the cans of essential-ly all of the oxygen. The second manufacturerevacuates the cans to 27 “in” of mercury andleaves a residual amount of oxygen. The coffeeproduced by the first manufacturer would be ex-pected to have a longer shelf life than that of thesecond, yet this fact would not be reflected in thedate of manufacture. The date of manufactureplaced on a product with no explanation of whatkind of date it was would also tend to confuse theconsumer who might interpret it as an expirationdate and assume that it was already beyond itspredicted shelf life.

Many manufacturers use coded dates of manu-facture, and this practice could be changed to anopen date for coffee and tea. Open pack dating orcoded dating would assist in stock rotation for theprocessor, distributor, transporter, and retailerto allow a “first-in, first-out” system. A codeddate could also include other information such asthe factory, shift, lot number, etc. to aid in inven-tory control and tracing of an item should a con-sumer complaint ever occur or a recall be neces-sary. The tracing of a consumer complaint wouldmean that the code must be placed on each pack-age of food.

Sell-by date. Placing a sell-by date on coffee ortea products would be beneficial; however, theshelf life of these products is long, and abuse

might make these dates meaningless. The onlyproduct for which a sell-by date would be ap-plicable would be ground roast coffee packagedin bags, since the shelf life of this product is muchshorter than that of coffee packaged in vacuumcans. Some manufacturers already place an openpull-date on this product for the benefit of the con-sumer and as an aid in stock rotation, but thepractice of selling ground roast coffee in fold-topbags is usually localized and has become ratherscarce.

Best-if-used-by or use-by date. The shelf life ofcoffee or tea mainly depends on the storage condi-tions such as temperature and relative humidi-ty—especially after the product has been opened.Storage of instant coffee or tea mix, for example,with the lids open or loosely screwed on wouldresult in moisture pickup and caking of the prod-uct. Storage of ground roast coffee in an unsealedcontainer would result in faster staling.

A use-by date would also result in wastage notonly because the consumer might reject the foodin the grocery store because of the date but alsobecause an expiration date would give the im-pression that the product should not be consumedfor health reasons after a certain period of timewhen, in fact, no health hazard exists when agedcoffee or tea is consumed. Food deterioration isalso a gradual process, and rarely is a productgood one day and bad the next. Shelf-life predic-tions for the same product can differ from onemanufacturer to the next, since the end of shelflife is often a subjective decision, and a consumermay unjustly reject a product with a conservativeshelf life in favor of the same product producedby a different manufacturer with a more liberalshelf-life prediction.

The same storage information collected by themanufacturer can be used to implement a best-if-used-by date based on minimal changes in flavorand odor during storage and does not have thedisadvantages discussed above.

Spices, Sugar, and Salt

Modes of deterioration. Flavor, pungency, andcolor may be lost from spices by either physical orchemical routes, The active principles of mostspices are organic compounds in the volatile oilfraction. Whole spices retain essential oils verywell, as illustrated by the 5-year shelf life ofwhole cumin at room temperature. But loss ofthese volatiles can be a problem in ground spices.In ground spices, the temperatures during and im-

76 ● Open She/f-Life Dating of Food

mediately after grinding have been found to be im-portant in retaining essential oils.

Color loss from capsicum spices (paprika andred peppers) is thought to be an oxidation reac-tion that may be induced by light, pro-oxidants, orcoupled with other oxidation such as lipid oxida-tion. Increasing storage temperature and de-creasing water activity seem to increase the rateof color loss as is true of lipid oxidation. In sweetred paprika, the color seems most stable at aW

0.65. However, at this aW, caking and browningbecome problems.

Pure sucrose is not susceptible to microbial orchemical deterioration, but sugar can becomeunacceptable to the consumer if contaminated byinsects or rodent droppings. Excessive moisturegain leading to caking can also render the pack-age unacceptable. However, these failures are in-dicative simply of poor storage or packaging fail-ure. Under proper storage conditions, granulatedsugar should be indefinitely shelf-stable.

Brown sugar, which is susceptible to moistureloss resulting in an extremely hard mass, is sealedin plastic or waxed bags for retail sale. Confec-tioners’ sugar is susceptible to moisture gainresulting in caking, but anticaking agents such ascornstarch are added to combat this problem. Theshelf life of confectioners’ sugar is about 18months at 21° C. The Q10 is about 2 for both brownand confectioners’ sugar, based on moisture gain.

Table salt (NaCl) is not susceptible to microbialor chemical deterioration. However, pure salt isvery hydroscopic and will absorb moisture fromthe surroundings above 75-percent RH. For thisreason, anticaking agents are added to salt to en-sure the free-flowing property. Stored in mois-ture-proof containers, salt will remain indefinite-ly stable.

Sensory quality (aroma, pungency, taste, andcolor) is the determining factor for shelf life ofspices. Although some spices, notably paprika,are rich in vitamins, they are not consumed fortheir nutritive value. Spices imported from areaswith poor sanitary facilities can have high loadsof micro-organisms and be contaminated with

aflatoxin via rodent or insect infestation or inclu-sion of extraneous plant material, Although con-taminated spices can be sources of inoculum forfoods, microbial contamination per se does notlimit shelf life of spices because most spices aretoo dry to permit growth. Fumigation with ethyl-ene oxide can be used to reduce the microbialload of spices.

Neither safety hazards nor nutrient loss occursin sugar or salt, No sensory losses occur in salt orgranulated sugar. Functional loss can occur inbrown and confectioners’ sugar because of mois-ture loss/gain, resulting in loss of free-flowing-ness.

Pack date. Very little published data are avail-able on deterioration of spices. However, sincewholesalers sell oleoresin, oils, and extracts to in-dustrial users at certain specifications, it wouldbe surprising if these wholesalers do not havedata on storage stability of spice products.

Considering this lack of published data, how-ever, a legible pack date would be of little or novalue to consumers. Indeed, it is interesting tospeculate whether or not the majority of consum-ers, with no standards for comparison, have anyidea as to the strength of spices in terms of taste,pungency, or color. A pack date on sugar or saltwould also be of little or no value,

Sell-by date. A sell-by date with no instructionsfor storage or to use within a specified time forbest results is of little value in products such asspices, sugar, and salt that tend to be stored forlong periods before use in the home.

Best-if-used-by date. A statement to the effect“for best flavor results, use before “ w o u l dbe the most useful method of open dating for con-sumers of ground spices. However, even with ade-quate data made available. the simple loss ofpungency and color is a subjective judgment. Ause-by date has no relevance for salt and granu-lated sugar with indefinite shelf life, Instructionson methods of reversing the hardening and cakingof brown and confectioners’ sugar would be morebeneficial than would a best-if-used-by date.

Appendix B

Bask Food Preservation andDeterioration Modes

INTRODUCTION

As pointed out in chapter V, in order to establish a fairly accurate open date for aparticular food, one needs to know how that food deteriorates. This appendix contains anin-depth look at the various modes of deterioration and how they impact on open dating. Itspecifically describes the general modes of deterioration leading to the quality and nutri-tional losses and types of preservation used to slow down the modes.

Biological Decay-Preharvest

Prior to harvest and slaughter, foods—whetheranimal or vegetable—are subjected to a myriadof microbiological diseases, including viruses,molds, yeasts, and bacteria, In addition, somefoods before harvest can be eaten by insects,birds, or rodents, or become prone to disease. Forplants, competition by weeds can result in poorquality. Controls for such ravages can includepesticides, herbicides, rodenticides, weeding ma-chines, and livestock antibiotics.

Preharvest deterioration as such is not general-ly considered in open shelf-life dating. However, iffood is subject to damage, its initial quality will beless. Since processing does not make low-qualityfoods better, overall shelf life would be less afterslaughter or harvest, as compared with undam-aged foods,

Senescence (Aging)

Once a fruit, vegetable, cereal grain, or animalproduct is harvested or slaughtered, it is sepa-rated from its source of nutrients and water.Since it is still a viable living system, the enzymescontinue to operate and utilize the carbohydrate

and nutrient stores. For fruits, this process can beof benefit because postharvest damage can berepaired. More importantly, fruits can be pickedprior to optimum maturity and transported longdistances to the marketplace and home, duringwhich time they develop into a high-quality prod-uct, If the fruits were picked at optimum ripeness,they could rot before consumption during thistransportation. This biochemical process alsooperates in the aging of meat to achieve the de-sired degree of tenderness. However, the state ofthe preslaughter animal is very important and af-fects the final product quality,

Eventually, though, for all foods, postharvestenzymatic processes lead to degradation of sen-sory quality, including loss of color, flavor, nutri-ents, and texture. In addition, the breakdownproducts themselves damage the tissues such thatthe decaying process becomes more rapid. To pre-vent this deterioration, three major control meth-ods can be used: 1) lowering temperature, whichslows the rate of the reaction; 2) raising the tem-perature, which denatures the enzymes andmakes them inactive but changes the sensor y

quality of the foods; and 3) removing or bindingwater to reduce water availability (or water ac-tivity, aw), which reduces the ability of the en-

77

L+ 9-39 L+ 0 - - 9 - “

—

78 . Open She//-L//e Dating of Food

zymes to operate. Other control methods are addi-tion of acid, thereby lowering pH; reduction ofoxygen level or increase of carbon dioxide (CO2),which slows the reactions; and genetic manipula-tion of the food to altogether prevent the reac-tions. With respect to open dating, the effects ofaging are important in determining shelf life offresh fruits and vegetables; whole grain cereals;fresh meat, poultry, and fish; and, to some degree,dairy products.

Microbiological Decay

Micro-organisms are responsible for qualityloss of many foods, especially fresh ones. Thereason is twofold: I) microbes are everywhere inthe environment and can grow very rapidly, and2) after a food is harvested or slaughtered, it losesto some degree the ability to fight off microbial at-tack, If the food is physically damaged—even bynormal trimming and cutting—it becomes moresusceptible to attack,

As noted, microbes can grow rapidly on foods.Starting with one microbe that divides every 10minutes, in 5 hours (if the nutrients were avail-able), there would be over 1 billion microbes.Much of the same controls used for enzymes canalso be used for microbes:

lower temperature to slow growth,raise temperature to kill microbes,remove or bind water to slow or preventtheir growth,lower pH to slow or stop their growth by add-ing acid or by natural fermentation,control oxygen (O2) level to control popula-tion or increase CO2 level, andmanipulate food composition to remove nutri-ents needed by the microbes.

Because in some cases the above methodschange the food into a form not desired by theconsumer or the method is not adequate to extendshelf life, some chemical means of preservationmust be used to slow the growth or kill the micro-organisms. Examples are calcium propionate inbread; sodium benzoate in some soft drinks; andnatural fermentation that produces alcohol, suchas making wine from grapes. Usually only smallamounts of the chemicals are used, so that theywill have no ill effect on the consumer.

Knowledge of how environmental conditions af-fect the growth rate of microbes is very importantin predicting shelf life, and thus determining theopen dating of many foods including:

● fresh and ground meats and poultry;. fresh fish;

●

●

●

●

●

dairy products such as milk, cheese, andyogurt;cured meats such as hot dogs, bacon, andsalami;pasteurized fruit drinks:fruits and vegetables; andwhole grains.

A second and more serious problem with micro-organisms is the fact that some are pathogenic tohumans—that is, they either cause an infectionwhen ingested or while growing produce chemi-cals in the food that are toxic to humans. Mostfood processes are designed to ensure againstcontamination with pathogens or growth of thepathogen after processing, For example, fermen-tation of foods with useful microbes producesalcohol or acid that prevents the growth of patho-gens. Some of the major micro-organisms patho-genic to humans in foods are:

Ž Intoxicants—Staphylococcus aureus,—Clostridium botulinum,—Clostridium perfringens, and—Aspergillus flavus.

● Infect ious—Salmonellae species, and—Escherichia coli strains.

In most cases, temperatures below 7° C, foodwith a water availability of less than 80-percentrelative humidity (aW or water activity of 0.80),and a pH of less than 4,5 are sufficient conditionsto prevent the growth of pathogens. Open datingshould not be based on the growth of these orga-nisms, since the manufacture and subsequenthandling and distribution should ensure absolutecontrol of these pathogens. Unfortunately, if thelatter is not done, consumers may have a falsesense of security that a food consumed before itssell-by or use-by date is safe when in fact it couldcause food poisoning. This fact points to a must ineducating the consumer that open dating is not anabsolute assurance of food quality or food safety,

Chemical DeteriorationDuring the processing of foods, tissue damage

occurs that causes the release of various foodchemical constituents into the cellular fluid en-vironment. These chemicals can then react witheach other or with external factors to lead todeterioration of the food and result in a short-ening of shelf life, Although many different reac-tions are important that lead to quality and nutri-ent loss, the major ones are classified below.

Appendix B—Basic Food Preservation and Deterioration Modes w 79

Enzymatic. As mentioned earlier, normal post-harvest enzymatic reactions can lead to a loss infood quality and shelf life. In addition, destructionof cell tissues releases enzymes that can lead tofurther deterioration. For example, lipoxidase en-zymes released from cell organelles called mito-chondria can attack lipids and cause rancidity.Similarly, the polyphenol oxidase enzyme can re-act with some cell constituents and oxygen, caus-ing a brown color, which is typically seen as a de-terioration reaction in bruised or cut fruits suchas apples or bananas, These reactions are usuallyvery rapid at room temperature once the food ishandled but are controlled in the natural state.The reactions can also occur in the frozen stateunless the enzymes are denatured by blanching.Enzymatic reactions are also the major mode ofdeterioration of many refrigerated doughs, sincethe flour cannot be heat treated because it resultsin loss of dough functionality. Control of the en-zymatic reactions is the same as was discussedfor senescence.

Knowledge of how environmental conditions af-fect the rate of these reactions is very importantin predicting shelf life—and thus for open dating.The major environmental factors are oxygen,water, pH, and temperature. Other enzymaticdegradations include color losses and vitaminlosses, such as loss of vitamin C in fresh produce.

Lipid oxidation. Many foods contain unsatu-rated fats that are important in the nutrition ofhumans. Unfortunately, these fats are subject todirect attack by oxygen through an autocatalytic-free radical mechanism that results in rancid off-flavors, making the food undesirable to consum-ers. Very little fat has to oxidize for the consumerto detect rancidity and reject a food, even thoughit may still be edible and nutritious. The freeradicals and peroxides produced in this reactioncan react and bleach pigments, such as in driedvegetables, if stored for a long time; can destroyvitamins C, E, and A; can result in protein degra-dation, thus lowering quality as may happen dur-ing storage of whole dry milk; can cause darken-ing of fat at high temperature, as happens indeep-fat frying; and can produce toxic substancesduring long storage that have been implicated insome animal studies as potential carcinogens.

Thus, knowledge of the rate of lipid oxidation isimportant in foods where it might be the principalmode of deterioration such as in:

● fried snacks (e. g., chips),● n u t s ,● dried meats/vegetables/f ish/poultry,● ce rea l s ,

●

●

●

●

●

●

●

●

●

●

●

wheat germ,frozen vegetables/mea ts/fish/poultry,some dairy products,semimoist meat products,precooked refrigerated meats and fish,cured meat and fish,coffee,cooking and salad oils,margarine,spices, anddried vegetables, such as potatoes and car-rots.

Rancidi ty development can be control leddirectly by eliminating oxygen (which is very dif-ficult to do) and by adding antioxidants such asBHA, BHT, and EDTA. The rate of reaction alsodepends on temperature to some degree (rate in-creases two to three times for every 10° C in-crease in storage temperature for dry foods) andon water availability y or water activity (aw). Foodsif too dry or not dried enough are more subject torancidity. For example, as potato chips gain orlose moisture, they become rancid faster. Mois-ture gain is more detrimental than loss. Light andtrace metals (such as used in fortification) cata-lyze the reaction. Rancidity can also occur in thefrozen state where it is more sensitive to tempera-ture changes (rate increase of 6 to 10 times for a10° C increase in temperature. )

A knowledge of the rate of these reactions canbe used to predict shelf life and thus open datefoods. Knowing how fast oxygen permeates a foodpackage is also necessary to predict shelf life. Inaddition, the consumer must be instructed as tothe extent and control of this reaction so as to bet-ter maintain the quality and nutritional value ofthe food in the home.

Nonenzymatic browning (NEB). NEB is anothermajor chemical reaction leading to loss of qualityand nutritional value. This reaction occurs be-tween reducing compounds (such as glucose, fruc-tose, and lactose) and amino acids or proteins. Inaddition, browning can result from heating sugarsto very high temperatures (carmelization). In cer-tain cases, the reaction is desirable such as in thetoasting of bread: the crust formed in roastingmeats; malting of barley for beer and spirits man-ufacture; and the production of syrups, molasses,and caramel candies.

Undesirable aspects of NEB lead to bitter off-flavors; darkening of light-colored dry products,such as nonfat dry milk; loss of protein volubility;toughening of protein foods; and, most significant-ly, a decrease in protein nutr i t ional quali tycaused by the binding of an essential amino acid,

80 ● Open Shelf-Life Dating of Food

lysine, in the reaction. NEB is a significant reac-tion leading to end of shelf life in processed pro-teins; dry milk and whey powders; dry whole eggs;dehydrated meat and fish; frozen meat, fish, andpoultry; breakfast cereals; cake mixes; fortifiedpasta; intermediate-moisture breakfast bars andmixes; and some concentrated juices. In concen-trated juices, ascorbic acid (vitamin C) acts as thereducing compound and results in loss of vitaminvalue as well.

The environmental factors that control NEB aretemperature, pH, and aw. NEB is more sensitive totemperature than is rancidity in dry foods, in-creasing four to six times in rate for a 10° C in-crease in temperature. In foods in which bothbrowning and rancidity can occur, at high tem-peratures NEB predominates, while at low tem-peratures rancidity predominates. During proc-essing, exposure time at high temperaturesshould be minimized, since it leads to excessivebrowning precursors that can shorten shelf lifeduring subsequent storage. Lowering of pH slowsbrowning but is not a desirable method of proc-essing because of the flavor problem of addedacid. The major control of browning is throughcontrol of the amount of aw in the food in whichthe reaction can occur. The lower the water con-tent, the slower the reaction rate for the foodsmentioned above. However, very moist foods suchas fresh or canned products brown slowly be-cause the reactants are diluted by the high watercontent and thus there is aw (0.6 to 0.8) at whichpoint the food undergoes a maximum rate ofbrowning.

With respect to open dating, knowledge of therate of browning as a function of temperature andwater content is very important in order to pre-dict shelf life accurately. How fast a food packagegains moisture will also significantly affect shelflife for these types of products.

Other chemical reactions. Other chemical re-actions that can lead to food deterioration includethe thermal destruction of vitamins such as vita-mins A, B1, and C; the effect of light on pigmentssuch as the browning of meat and bleaching ofchlorophyll; the effect of light on riboflavin; thedirect oxidation of vitamin C; and the direct oxi-dation of carotenoid pigments. In every case, theeffect of temperature, oxygen level, moisture con-tent, and light must be known to be able to predictthe rate of the reaction so that the time to reachthe end of shelf life can be measured. Of impor-tance in all these reactions is a decision as towhat extent of deterioration is considered to bethe end of shelf life. In many cases, this data must

be correlated with actual organoleptic and sen-sory testing of the food so that the correct index ofdeterioration can be chosen.

Physical Deterioration

Physical damage can also lead to loss of shelflife. The types of physical damage can be classi-fied into various categories, as was chemical de-terioration.

Physical bruising/crushing. This mode of dete-rioration is related to physical abuse of the foodin harvest, processing, and distribution. It is mostimportant to fruits and vegetables, since physicalabuse leads to microbial attack and decay. Pack-aging to prevent abuse is a key to long shelf life.With dry materials such as chips, crushing canlead to unacceptability based on consumer de-sires, This cannot be equated to open dating orloss of shelf life, but proper packaging and carecan eliminate this problem.

Wilting. Fresh leafy and tuber vegetables candeteriorate if subjected to low relative humidity.Under these conditions, they lose moisture to thesurroundings, resulting in loss of crispness and anincreased rate of senescence reactions with sub-sequent quality and nutrient losses. Proper knowl-edge of the rate of moisture loss for various pack-aging materials and the maximum allowable mois-ture loss can be used as one means of setting opendates of use for fresh produce.

Moisture loss/gain. With some food productssuch as candy, semimoist pet foods, cakes, andbread, moisture loss leads to an increase in har-dening. If a limit of hardness is known to be unac-ceptable, predictions of the time to reach thislevel based on equations that describe moisturechange with time can be used as one method ofpredicting end of shelf life. From this, the opendate for use can be set. Similarly, one can predictthe moisture loss from flour, pasta, and similardry products for which a natural loss of moistureoccurs and a net weight limit is set for sale.

Some products that gain moisture have a tex-tural limit at which they become too soft, such aspotato chips, other dried or fried snacks, andcrackers. In addition, some crystalline foods suchas sal t , brown sugar , convenience dry-mealmixes, dry coffee, dry teas, and dried drink mixeswill gain enough moisture to become sticky andcaked. Predicting shelf life, based on a gain of acritical amount of moisture, is possible if thetemperature/relative humidi ty condi t ions areknown as a function of time and the permeabilityof a package to moisture is known.

Appendix B—Basic Food Preservation and Deterioration Modes ● 81

Temperature-induced textural changes. Tem-perature fluctuations per se can affect physicalmodes of deterioration. For example, the continu-ous rise and fall of temperature around a phase-change point leads to melting of fat and the subse-quent deterioration of quality of some candiesand formulated foods. In frozen foods, repeatedthawing and freezing cause loss of tissue moistureand increased chemical reaction rates. If. the tem-perature fluctuation does not exceed the thawingpoint, package ice, caused by evaporation of thewater from the food into the package space withsubsequent freezing as ice crystals, can occur.This results in consumer unacceptability. In addi-tion, if the water loss is significant from a par-ticular surface region, freezer burn—an undesir-able discoloration caused by enhanced chemicalreaction— can occur. This also is unacceptable tothe consumer. Finally, some temperature fluctua-tions can result in emulsion destabilization ofproducts such as mayonnaise, margarine, saladdressings, and dessert toppings.

Knowledge of the sensitivity of these reactionsto the degree of temperature fluctuation and aknowledge of the possible fluctuations occurringin distribution and in the home are needed inorder to predict shelf life, In most cases, manufac-turers formulate the product to withstand any

abuse that may occur. Heating itself can alsocause textural changes. In this case, the reactionis usually desirable as in the canning and/or cook-ing of vegetables, meat, fish, and poultry, Canningat high temperatures is usually undesirable forfruits as they lose their desirable crisp textureand develop a cooked flavor. However, these tex-tural changes are usually not of concern in thestorage deterioration of foods.

Staling. Staling is a mode of deterioration im-portant in processed wheat flour products suchas bread and cakes. The reaction is basically acrystallization of amylopectin, one of the majorstarches present in wheat flour. The rate is in-creased as temperature decreases—opposite tothat of the chemical, enzymatic, and microbial re-actions discussed earlier, Thus to prevent staling,the food must not be refrigerated. However, notrefrigerating the food can lead to other reactions,causing loss of shelf life.

Chemically induced textural changes. As men-tioned in the section on chemical deterioration,both lipid oxidation and nonenzymatic browningcan result in breakdown of proteins, leading totoughening and an undesirable loss of shelf life.Control and prediction were discussed previous-ly.

BASIC FOOD- PROCESSING PRINCIPLESThe previous section discussed the modes of

food deterioration that lead to loss of shelf lifeand gave examples of prevention. In this section,the basic principles of the major food processmethods are listed.

Use of TemperatureHeat preservation. The use of heat to preserve

foods is based on the principles of:● destruction of pathogens,● destruction of spoilage microbes,● denaturation of enzymes, and• softening of tissues to make them more di-

gestible.Blanching, a food process, is the application of

heat under mild conditions, or at high tempera-ture for a short time, to achieve enzyme degrada-tion, drive out oxygen, and soften food tissues. Itis used as a preprocess step for canning, freezing,and drying to minimize quality and nutrient lossesbefore the product is preserved.

Pasteurization is a mild heat treatment used toreduce the number of live micro-organisms in foodso as to extend shelf life as well as to destroy keypathogens. A pasteurized product is not sterile,however, so some spoilage organisms can growback and will eventually lead to spoilage. Pasteur-ization can also be accomplished at high tempera-ture for a short time period, which results in thesame reduction of microbes as under mild heat,but with less cooked flavor.

Canning is the process of heat treatment todestroy all organisms of pathogenic nature andmost important spoilage organisms. The safety ofthe process is based on the time needed to reducethe population of Clostridium botulinum by a fac-tor of l-million-million at the most heat-resistantpoint in the food, since this micro-organism is themost heat-resistant and most harmful pathogen.Not all of these types of organisms are killed, how-ever, since some are more heat-resistant than isClostridium botulinum but do not grow under nor-mal canned-food storage conditions. If the food is

82 ● Open Shelf-Life Dating of Food

subjected to high temperature (40° to 50° C), theywill grow, causing the food to spoil. Processing todestroy these organisms will destroy the foodquality. Because an adequate heat treatment isused, canned “commercially sterile” foods havelost some color: have lost 20 to 30 percent of somevitamins; have a cooked flavor; and have devel-oped a softer texture. Subsequent deterioration isusually confined to chemical modes of decay thatdo not require oxygen, since the can is hermeti-cally sealed.

Cold preservation. The basis of refrigerationand freezing is that the lower the temperature,the slower the rate of most deteriorative reac-tions such as senesence, enzymatic decay, chemi-cal decay, and microbial growth. Microbes, infact, usually cannot grow below - 5° to - 10° Cso that freezing stops microbial growth. In somecases, lower temperature increases deteriorationbecause the fracture of membranes releases deg-radative enzymes, which occurs in chill injuryand freezing of some fresh fruits and vegetables.It has been found also that freezing to just belowthe freezing point of some foods increases deteri-oration by chemical reactions. This is because notall the water is frozen out and the chemicals areconcentrated in the remaining water. Finally, inrefrigerated foods, some microbes grow better atlower temperatures, since they can compete bet-ter against other spoilage micro-organisms andhave a lower optimum growth temperature.

Control of Water Content

Concentration and drying. As water is removedfrom a food, less is available as a solvent andmedium for the deteriorative reactions. Thus,most chemical reactions decrease in rate as thewater content decreases. Unfortunately, in theprocess of removing water, the reactants firstbegin to concentrate so that the rate of reactioncan initially increase. To prevent this, the tem-perature is kept low during the process, or thewater removal is done rapidly enough to getthrough the danger zone. The degree of drying orconcentration is best represented by a factor thatdescribes the aW in the food.

Figure B-1 depicts a typical moisture absorp-tion isotherm that gives the relationship betweenmoisture content (on a dry basis) and aW . On ageneral basis, a significant amount of water mustbe removed to lower the aW significantly below 1(e.g., at 1 g H2O/g solids or 50- percent water, theaW. is still very close at 1.0). AW can also be defined

as relative vapor pressure or by ERH as defined inequation 1:

a (1)where

p = the vapor pressure of water in the foodpo = the vapor pressure of pure water at the same

temperature of the food% ERH = the percent relative humidity in equiIibrium

with the food at which it neither gains norloses weight

Of consequence is the fact that for most foodsin their natural state the aW is high, and thus ratesof many reactions including microbial growth arealso high. In order to preserve the food, the aW canbe lowered by concentrating, drying, or by addingwater-binding agents such as sugars and salt. Thepoint on the isotherm of maximum stability is theBET monolayer value (mO in figure B-1) which is ata low aW. In general, the rates of most chemicalreactions follow the pattern shown in figure B-2—that is, the rate of reaction increases above themonolayer value, reaches a maximum, then de-creases again, Rancidity is unusual in that therate increases again below the monolayer value.

Basically, as aW is lowered, microbial decay isinhibited first, with bacteria being the most sen-sitive and molds the most resistant to lowered aW.Browning, enzymatic activity, lipid oxidation, andnutrient loss also decrease as aW decreases, withNEB showing a definite maximum rate at an aW o f0.6 to 0.8.

Concentration is used basically as a preprocessstep for foods such as frozen concentrated juices,concentrated canned soups, condensed sweet-ened milk, and in the preparation of a liquid con-centrate that is to be spray-dried, such as for drymilk, dry coffee, dry tea, and some dry food sup-plements like yeasts. In these latter processes,preconcentration is used because it is a cheaperway to remove water than is drying. However, be-cause of viscosity effects, not all water can beremoved, so further drying is required. Duringconcentration, the temperature is usually low,since a vacuum is used. Thus, a cooked flavor andnutrient losses are minimized.

In drying, heat is applied and the relativehumidity surrounding the food is lowered so thatthe water will be evaporated from the food. Toachieve both, the air passing over the food iswarmed, supplying the energy to remove thewater and lowering its humidity. Solid piece mate-rials like vegetables for soup mixes are dried inan air tunnel at 50° to 65° C for 4 to 8 hours.Slurry material like potatoes are dried in thin

Appendix B—Basic Food Preservation and Deterioration Modes .83

1.0

0.9

0.8

0.7

0.6

0.5

0.4

Typical isotherm[lower region]

2Moisture content (g H,O/g dry solids)

4

0.3

0.2

0.1

1

Figure B-1 .—Moisture Content v. Water Activity

Figure B-2.— Effect of aw on Rate

Relativerate

aW

layers on hot rotating drums (I ZOO to 1400 C) in 2to 3 minutes. Although the latter process is at ahigher temperature, since it is shorter in time,less quality and nutrient damage takes place.Concentrated liquids can be dried by sprayinginto a vertical tower through which air at 200 0 t o250° C is passed. In this case, drying occurs in 3to 20 seconds, so very little damage takes place.Freeze-drying creates the least damage, since it isdone at low temperatures in a vacuum. In each

case, the principle is to lower the water contentand thus the aW to a level such that during stor-age, reactions proceed at a very slow rate. Theoptimum for most foods is at the predicted mono-layer value.

It is thus imperative that good packaging beused to prevent the chemical reactions describedabove, to prevent moisture gain to the point ofmicrobial growth, and to prevent any physicalchanges caused by moisture gain. If the productcontains unsaturated fat, it must also be vacuumpacked or nitrogen-flushed to slow the reaction.The rate of oxidation does not drop as much asdesired at low oxygen pressure, but the loweringof total oxygen availability limits the overall ex-tent of the reaction. Antioxidants actually have amuch better effect on limiting the reaction butmay not be able to be incorporated into all dryfoods, In some cases like cereals, the antioxidantsare lost in the baking process, so they are addedinto the packaging material.

Humectant use. Rather than removing water bydrying, the ability of the water present in foods toact as a medium and solvent can be reduced byadding water-binding agents (humectants) to thefood. All dry food solid components have this

84 ● Open Shelf-Life Dating of Food

ability, but the lower the molecular weight, thebetter the aw-lowering effect. The common agentsused are called humectants. Sugars and salts aresuch agents, having in fact been used as ancientpreservation processes in fermentation, salting,and sugar curing. Addition of sugar or salt inthese curing processes is required to lower the aW

to a level below which pathogens and/or spoilagemicrobes cannot grow, and in the case of fermen-tation to allow the desirable microbes to grow.

Control of pH by adding acid and growth in-hibitors such as antimycotics may be used in con-junction with the humectants where fermentationis undesirable. The result is a shelf-stable foodthat does not require refrigeration. Common ex-amples are the intermediate-moisture pet foods,confectioneries, some bakery goods, and break-fast tarts. These foods are subject to chemical de-terioration because of the high aW and to moistureloss if left in a dry environment,

Extrusion. Extrusion is a process utilized formany cereal foods, dry snacks, dry animal food,and semimoist pet foods. In this process, a doughis made which is then passed at high pressure byscrew action through a cylinder that is heated.The heat causes the components to interact, giv-ing the desired flavor, color, and texture, and asthe product releases from the screw, the internalsteam in the paste expands and flashes off, Thisresults in further textural changes and drying ofthe product. In some cases, further air-dryingmay also be used. Packaging requirements anddeterioration mechanisms are similar to thatdescribed for dry foods. Of significant importanceis moisture gain that can result in a soft, undesir-able texture.

Other methods. Deep-fat frying is a dryingprocess in that the hot oil provides the heat toevaporate off the water. In this process, the oilreplaces the water in the pores of the food. In bak-ing, the hot air in the oven serves as the dryingmedium—the longer the baking time, the lowerthe final moisture of the product. Freezing alsocan be considered as a drying process; however,the liquid water is converted into a solid thatbecomes unavailable, It should be noted that formost foods, about 20 to 30 percent of the water isstill unfrozen at – 200° C. Therefore, reactionsare not stopped by freezing; they are only sloweddown due both to lower aW and low temperature,

Chemical Preservation

Fermentation. Fermentation is one of the oldestof the known food processes. In this method, adesirable organism is allowed to partially convertsome of the carbohydrates of the food materialinto acid, alcohol, and flavor compounds. This canbe done naturally by changing the environment,especially the aW, of the food so that the desiredorganisms can grow (for example, adding salt tocabbage which inhibits spoilage but allows desir-able bacteria to grow). Industrially, a starterculture of the desired organism is usually addedto ensure that proper fermentation takes place.The basic principle of the process is to allow theformation of desirable chemicals, such as flavorcomponents and acids or alcohol, the latter ofwhich prevents the growth of undesirable spoil-age or pathogenic organisms. The shelf life of fer-mented foods is limited by the growth of the de-sired organism. In some cases, further processingis done such as in pasteurizing beer, wine, andvinegar, or the product is kept refrigerated suchas in yogurt and cheeses.

Additives. Chemical additives can be used topreserve and/or prolong the shelf life of foods.Each has a specific action by which it operates,The various classes are listed below.

●

●

●

●

Acids, such as citric and phosphoric acid.These lower the pH and inhibit undesirablemicrobes as well as slow undesirable en-zymatic and chemical reactions. Acids alsocontribute to flavor,Humectants, such as salt, sugar, and glycer-ol. These bind the water present, loweringt h e aw , and t hus r educe t he r a t e s o fmicrobial growth, enzymatic activity, andchemical reactions.Smoking of foods. This process depositschemicals from the smoke of burning woodchips onto the surface of foods that inhibitmicrobial action. The heat also destroyssome of the microbes. Because of potentialtoxicity problems, most manufacturers todayuse a liquid smoke product from which toxiccomponents have been extracted.Metabolic inhibitors, such as calcium propio-nate and sodium benzoate. These are chem-icals that take action against specific typesof microbes. They are used where furtherprocessing of the food results in undesirable

Appendix B—Basic Food Preservation and Deterioration Modes ● 85

quality and nutritional changes. Gases canalso be used as chemical sterilants and to killorganisms in grain. Ethylene oxide is an ex-ample as is chlorine applied in a solution tothe surface of fresh meat.Anticaking agents, such as the silicates.These are high water-binding agents used indry-powdered or crystalline foods to preventcaking by selectively binding the water.Antioxidant, such as BHA and BHT. Theseact in the lipid oxidation reaction to slow therate and thus extend shelf life.Chelating agents, such as EDTA and citricacid. These chemicals tie up trace metals toprevent them from catalyzing undesirable re-actions such as rancidity.Others. Other chemicals such as calciumsalts are used to prevent softening of fruitsand vegetables during the canning process.Sodium polyphosphates help to hold water incured and canned meats. Sulfite not only in-hibits microbes but slows down enzymaticbrowning reactions. Some additives are usedfor mainly esthetic purposes to enhance orrestore those flavors or colors lost duringnormal preservation or for manufacture ofengineered foods. Finally, nutrients can beadded totion.

Separationnew foods orout of milk or

restore those lost during preserva-

Separation

processes are used to either createingredients, such as making butterto transform a raw food into a more

DISTRIBUTION

Once a food is preserved and packaged, it is notstable forever. Each food system slowly decays ordeteriorates to the point where it is unacceptable.One goal of open dating could be to give consum-ers information as to the shelf life of the productso that it is consumed before it is unacceptable.The loss of acceptability, however, may not meanthe product is inedible—it only means that the es-tablished consumer quality unacceptability stand-ard has been exceeded. The problem is thereforetwofold: I) setting a standard for unacceptabilityand 2) determining or predicting the loss that oc-curs from point of distribution to point of con-sumption.

digestible or more stable form. Making flour fromwheat is an example of the latter. There are manydifferent processes that incorporate in generalthose methods already discussed above. For ex-ample, in the manufacture of instant coffee, thebean is fermented, ground, roasted, leached toform a liquid (the separation step), concentrated,then spray-dried and packaged. The shelf life ofthe product would depend on the effects of eachstep.

Gas Atmosphere Control

The shelf life of many fruits and vegetables de-pends on the rate of respiration after harvestwhich uses up the stored energy. This rate can bereduced by reducing the oxygen or by increasingC O2. The methods are generally classified as CAStorage (Controlled Atmospheric Storage) and in-clude:

● reduction and control of O2 by use of nitro-gen,

● hypobaric storage by pulling a vacuum eitherin a large truck or in a pouch, and

● use of both increased nitrogen and increasedC O2 in the headspace.

C O2 can also be injected into the headspace ofdairy and meat packages to reduce microbialgrowth and increase shelf life. Vacuum-packagingwith CO2 injection is used to enhance shelf life ofpoultry products, Overall, shelf life in these casesdepends on the degree of maturity after harvest,and temperature and permeability of the packageto oxygen and CO2.

HAZARDSData on actual

various productsshelf-life modes and shelf life ofbased on some endpoint stand-

ards have been collected and are in the main database part of this study. Appendix C discusses thesecond problem—that is, based on environmentalfactors, how can one predict changes in shelf life.The important environmental influences include:

●

●

●

●

temperature—increasing, decreasing, fluc-tuating:moisture (relative humidity)—gain, loss;oxygen level; andlight.

Appendix C

Technological Evaluation of

Shelf Life of Foods

INTRODUCTION

Appendix B covered the major modes of deterioration and the principles of process-ing foods. It can be concluded from that appendix that one of the major environmentalfactors resulting in increased loss of quality and nutrition for most foods is exposure to in-creased temperature. The higher the temperature, the greater the loss of food quality.Thus, in order to predict the extent of high-quality shelf life so as to be able to put a shelf-life date on a product, a knowledge of the rate of deterioration as a function of environ-mental conditions is necessary. * Coupled with this would be the need for knowledge ofthe actual environmental conditions to which the various classes of foodstuffs are ex-posed.

Basically, for each food item, each mode of deterioration was studied at several tem-peratures for up to 3 years. In addition, information as to temperatures in warehouses,boxcars, etc., was gathered. Many reports and tables resulted from the study. However,much is not applicable today because the various types of foods are processed different-ly, different packaging systems are used, the distribution system has changed, etc. Never-theless, one interesting outcome of the report was a nomograph {figure C-1), which givesthe prediction of quality for various food classes based on some rate of deterioration anda desired shelf life. What this graph says is that given a certain rate of loss, if it is cons-tant, one can predict the amount of change. Unfortunately, this simple method is not cor-rect for many foods and for many modes of deterioration such as nutrient loss, colorchange, and flavor change. This appendix covers the basic principles of how temperatureand other environmental factors affect the rate of food deterioration and how this can beused to predict the sell-by, best-if-used-by, or use-by date. These methods are not neededfor a pack date.

*The U.S. Army supported some major studies during the late-1940’s through 1953 to gain this information for the mil-itary food supply. The studies are summarized in S. R. Cecil<s and J. G. Woodroof’s (1962) “Long Term Storage of Mili-tary Rations”’ (Ga. Exp’t Station Tech. Bull. 25).

87

88 ● Open Shelf-Life Dating of Food

Figure C-1 .—Nomogram of Temperature, Time, andQuality for the Military Ration Items Used in the

Long-Term Storage Tests

k - Individual Items M - meatsC- confections D - dairy-typeB bakery or cereal X- miscellaneous (cocoa discs,V - vegetable or fruit cocoa powder, meat bars,

soup and gravy base)

{a}

(b)

w

71

Appendix C— Technological/ Evaluation of Shelf Life of Foods “ 89

What equation 2 means is that the percent ofshelf life lost per day is constant at some constanttemperature. This is the assumption used in thenomograph of figure C-1. Mathematically, if equa-tion 2 were integrated, the amount of quality leftwith time as a function of temperature becomesequation 3:

(3)

In terms of shelf life, this becomes equation 4:

(4)

OF LOSS OF SHELF LIFE

other defIned vaIue as measured In a consumertest)

In many cases, AC is not a very quantifiable,chemically, or measurable value and must bebased solely on human panel evaluation. In thiscase, Ao is assumed to be 100-percent quality andA e is just unacceptable quality, Thus, the rate ofdeterioration becomes the rate constant in equa-tion 5:

This is the assumption used in figure C-1. Techni-cally, the major problem in shelf-life testing is toverify that indeed n = O so that equation 4 or 5can be used. This is not easy to do, although somemodes of deterioration are directly applicable tozero-order kinetics. These include:

● Enzymatic degradation (fresh fruits and veg-etables, some frozen foods, some refriger-ated doughs);

● Nonenzymatic browning (dry cereals, drydairy products, dry pet foods, and loss of pro-tein nutritional value); and

● Lipid oxidation (rancidity development insnacks, dry foods, pet foods, frozen foods).

Based on this knowledge, one can predict theshelf life of a food at a given single temperature ifthe amount of loss at any time is known, For exam-ple, if it is known that a certain food has lost 50percent of its quality in 100 days if held at someconstant temperature, then:

Based on this, we could construct figure C-2which gives the shelf life left as a function of time(k is the slope of the line). As seen at 40 days,there is 80-percent shelf life left: at 160 days,there is 20 percent left: etc.

The main problem in establishing this graph isdetermining the criteria of what is to be meas-ured. That is, what is A or how much of A must belost to give an end of shelf life as perceived by theconsumer. It must be noted that shelf life is not afunction of time; rather, it is a function of the en-vironmental conditions and the amount of qualitychange that can be allowed. The second problemis that since food distribution occurs at variabletemperatures, this data must be collected at sev-.

90 “ Open Shelf-Life Dating of Food

Figure C-2.— Constant Shelf Life Lost

.

\20 -

10 -

n . 1 I I 1 1 I I I I20 40 60 80 100 20 40 60 80 200

Days

eral temperatures to be useful, Methods to applythis graph to variable conditions are describedlater,

Quality-Dependent Shelf-Life LossFunction

As discussed above, the shelf life in many casesdoes not follow a simple constant rate of deterior-ation. In fact the value of n can range for manyreactions from zero to any fractional value orwhole value up to 2. In fact many foods that do notdeteriorate at a constant rate follow a patternwhere n = 1 , which results in an exponentialdecrease in rate of loss as the quality decreases.This does not necessarily mean that the shelf lifeof foods that follow this scheme is longer thanthose with a constant loss rate, since the value ofthe rate constant is very important. Mathematic-ally, the rate of loss is, as shown in equation 6:

(6)

Integrating equation 6 gives a logarithmic func-tion as shown in equation 7:

(7)

A graphical representation of the amount ofquality left as a function of time is not a straightline as illustrated in figure C-3. If 50 percent islost in 100 days as in the previous example, thenat 40 days, there is 76 percent of the quality left.For a constant rate of loss, there would be 80 per-cent left, At 100 days, both mechanisms give thesame percent left, but after this time, the qualityloss slows down for the exponential mechanismand theoretically never reaches a zero value, Forexample, at 160 days, there is 33 percent left, andat 300 days, there is still 12.5 percent left. Thetypes of deterioration that follow an exponentialequation include:

●

●

●

●

●

●

rancidity (in some cases, as in salad oils ordry vegetables);microbial growth (fresh meat, poultry, fish,and dairy products);microbial death (heat treatment and stor-age);microbial production of off-flavors, slime,etc. (fresh meat, poultry, fish, and dairyproducts);vitamin losses (canned, semimoist, and dryfoods); andloss of protein quality (dry foods).

Another way of representing exponential de-cay in figure C-3 is to plot it in semilog as in figureC-4. The slope of this line is the rate that is cons-tant at constant temperature. Typically, for ex-ponential decay mechanisms, the rate constantcan be represented by 0,,, which is called the halflife. Mathematically, if one knows the amount ofdeterioration at any time at some constant tem-perature and if it follows a first-order reaction,figure C-4 can be easily constructed.

Figure C-3.—First-Order Degradation

20 40 60 80 10020 40 60 80 200 20 40 60 80 300

Days

Appendix C— Technological Evaluation of Shelf Life of Foods ● 91

Figure C-4.— First-Order Log Plot

I I I I I I50 100 150 200 250 300 350

Days

Very little data exists

of She9f-Life Loss

that describes food de-terioration by orders other than zero or first. Leeet al. (J. Food Sci. 42:640, 1977) and Sing et al. (J.Food Sci. 41:304, 1976) have described the deteri-oration of vitamin C in liquid foods such as tomatojuice or canned infant formulas by a second-orderreaction. In this case, the reaction is dependenton both ascorbate and oxygen—as the oxygen isdepleted, the rate of loss of ascorbate becomesless than that predicted by a first-order reaction,

Labuza (Critical Rev. Food Tech. 3:355, 1971)has reviewed the area of lipid oxidation kineticsand has found that oxygen uptake generallyfollows a half-order reaction with respect to oxy-gen for relatively pure lipids. However, additionof antioxidants changes the order to first order.In complex foods, however, the data best fit zero-order kinetics.

When sensory quality change is plotted againsttime, not infrequently the axiom “fresh is best”’ isviolated. For example, Kramer et al. (J. Food Qual.1:23, 1977) found an improvement in sensoryquality of certain prepared frozen foods afterfrozen storage for 3 months. After 6 months of

storage, sensory quality began to deteriorate andcontinued by approximately a first-order reac-tion. The entire curve, however, could best befitted as a cubic polynomial. Similar results wereobtained with reportable-pouch packed items bySalunkhe and Giffee (J. Food Qual. 2:76, 1978). Atypical curve for this type of response is shown asfigure C-5.

Such sensory responses can be explained onthe basis of psychophysical characteristics in-herent in sensory evaluations. They do not con-tradict the above general pr inciples of thekinetics of shelf-life loss. All that is indicated isthat consumers prefer (best) what they are ac-customed to, which is not always the freshestproduct. Thus, in the case of preference for 3-month-old frozen foods, the reason was that theproducts were initially overspiced and reachedan optimal flavor blend and intensity after 3months’ storage. In the case of the pouch/cannedproducts , consumers preferred products thatwere slightly degraded over the fresh. These not-unusual sensory responses indicate first the greatdifficulty in attempting a generalized predictionequation for shelf life and the need to study eachproduct individually. They also indicate thatfreshest is not always best, although open datingis predicated on the assumption that consumersare convinced that freshness and sensory qualityare the same.

Figure C-5.—Initial Quality Gain Prior toFirst. Order Degradation

Best

— - - - — - - -

Time

92 . Open Shelf-Life Dating of Food

TEMPERATURE DEPENDENCE OF RATE OF DETERIORATIONThe above analyses of loss of quality were

derived for a constant temperature situation. Thetemperature-dependent part of the rate of lossequation is the rate constant k. Theoretically, itobeys the Arrhenius relationship which statesthat the rate constant (or rate) is exponentiallyrelated to the reciprocal of the absolute tempera-ture. A plot of the rate constant on semilog paperas a function of reciprocal absolute temperature(l/T) gives a straight line. A steeper slope meansthe reaction is more temperature-dependent—that is, as the temperature increases, the reactionis faster, It is possible that food can deteriorateby two different mechanisms with different tem-perature dependencies. For example, dry pota-toes can go rancid and can become brown. Therates of each would have different temperaturefunctions. What this means is the dominant modeof deterioration could change with increasingtemperature to the faster reaction. This could bea problem in predicting shelf life,

Most data for modes of deterioration in the lit-erature do not give rates or rate constants butrather are in the form of overall shelf life as afunction of temperature, Mathematically, if only asmall temperature range is used (no more than20° to 400 C range), the data will give a fairlystraight line if the shelf life for some quality meas-urement is plotted on semilog paper as a functionof temperature as in figure C-6, This figure illus-trates the temperature sensitivity of two foods ortwo modes of deterioration, both giving a shelf lifeof 200 days at 25° C. Theoretically, to constructthis plot one needs: 1) some measure of loss ofquality, 2) some endpoint value for consumer un-acceptability, 3) data to measure the time to reachthis endpoint, and 4) experiments to measure thisloss for at least two temperatures so the line canbe constructed. The more temperatures used, thebetter the statistical significance of the data.

It is obvious from the graph that the steeper theslope, the more sensitive is the food (or the reac-tion) to temperature. A measure of this sensitivityis called the Q10 of the reaction that is defined inequation 8:

Q 10

=rate of loss of quality at temperature (T + 10°C) (8)

rate of loss of quality at temperature T ° C

The Q10 can also be calculated from the shelf-lifeplot as in equation 9:

Q 10 =shelf Iife at T°C (9)

shelf Iife at (T+ 10°C)

Figure C-6.--Shelf-Life Plot

I 120 25 30 35 40 45

Temperature “C

which assumes that the rate is inversely propor-tional to the shelf life.

As an example from figure C-6, it can be calcu-lated that for food A, the Q10 is:

Thus, food B or reaction B is much more sensi-tive to an increased temperature than is A.

This graph has practical applications in study-ing loss of shelf life. To illustrate, if studies at twodifferent temperatures are made, the shelf life atsome lower temperature can be predicted if theline is assumed to be straight. One cannot, how-ever, study the deterioration at only one tempera-ture, since it is not possible to predict beforehand

-.

Appendix C— Technological Evaluation of Shelf Life of foods Q 93

the shape of the line or the Q10 exactly. Table C-1illustrates how important the Q10 would be in pre-dicting shelf life at lower temperatures. It shouldbe noted that since different reactions may occurat different temperatures to cause end-of-productacceptability, the projected line might be incor-rect. For example, in figure C-6, reaction B wouldcause end of shelf life in 12 days at 300 C, butbelow 25° C, reaction A is faster and thus wouldbe the controlling factor in end of shelf life if thefigure referred to two major deterioration modesof a single food item.

Table C-1 .—Weeks of Shelf Life at a GivenTemperature for Given Q10

Q 1 0

Shelf life at2 2.5 3 4 5

50° c . . . . . . . 2 2 2 2 240° C . . . . . . . . . . . . . . . . . 4 5 6 8 1030° C . . . . . . . . . . . . . . . . . . . 8 12.5 18 32 5020” C . . . . . . . . . . . . . . . . . . 16 31.3 54 2.5 4.8

SHELF-LIFE Prediction FOR VARIABLE TEMPERATUREGiven that data as to the mathematical repre-

sentation of the reaction causing end of shelf lifecan be obtained and a shelf-life plot constructed,some simple expressions can be derived to predictthe extent of deterioration as a function of vari-able time/temperature storage conditions. Fromthis, either a use-by date can be calculated or asell-by date evaluated in which some shelf life leftfor home storage is figured in.

For zero order, the expression is as follows inequation 10:

I 1)1 \

If the time/temperature history is broken up intosuitable time periods as illustrated in figure C-7,the average temperature in that time period canbe found. The rate constant for that temperatureis then calculated from the shelf-life plot using azero-order reaction, and this rate constant ismultiplied by the time during the period. Thesethen are added up to get the amount lost for atotal of n segments.

If shelf life is based simply on some time to

Figure C-7.—Temperature/Time History

Ti

reach unacceptability. equation 10 can be simpli-

(11)

This equation says that the fraction of shelf lifelost for holding the product at some temperatureis equal to the time [0]) held at that temperature di-vided by the total time (0s) a fresh product wouldlast if held at that temperature.

To employ this method, the temperature historyis divided into n suitable time periods; the averagetemperature T i at each time period is evaluated;the time held at that temperature Oi is then di-vided by the shelf life (l. for that given tempera-

94 ● Open She/f-Life Dating of Food

ture. The fractional values are then summed up togive the total fraction of shelf life consumed. Thetime left at any storage temperature at which theconsumer may hold the product is the fraction ofshelf life remaining (1 – fc) times the shelf life atthat storage temperature from the shelf-life plot.

The U.S. Department of Agriculture (USDA) de-veloped this method, referred to as TTT, ortime/temperature/tolerance method (Conferenceof Food Quality, Nov. 4, 1960, USDA Agr. Res.Service, Albany, Calif.). Extensive references toits use can be found in the literature. For exam-ple, Gutschmidt (Lebensmittlen Forschung undTechnol. 7:137, 1974) applied this to storage-lifeprediction of frozen chicken with excellent re-sults, It must be remembered, however, that thisonly applies for reactions with a zero-order dete-riorative mechanism—a constant rate of loss atconstant temperature.

Zero-Order Shelf-Life Devices-Present Technology

A device that can be attached to a frozen foodpackage to integrate time/temperature exposurein the manner discussed above has been devel-oped (Kockums Chemical Company, BiomedicalScience Division, Reston, Va. ), Unfortunately, thedevice (i-point TTM) can only be used for reac-tions with the same temperature sensitivity or Q 10

if shelf life is to be predicted. Those available in1977 were i-point #1 Q10= 140; i-point #2 Q10= 6; i-point #3 Q10= 36. These devices could be used,however, to evaluate abuse during storage, andmodifications can be made to get other Q10’s.

The i-point device is based on an enzymatic re-action that is activated by breaking a seal whichmixes the enzyme with a substrate. Color changesthat occur with the subsequent reaction can indi-cate the days of shelf life left or the extent of deg-radation. Unfortunately, these devices have tem-perature responses that change above about

— 10° C, resulting in a different Q10 (of about 2.2).They also have very rapid response times above+ 10° C, so they cannot be used for foods withlong shelf life (e.g., dehydrated foods).

The present cost of these devices prohibitstheir use on individual packages, but they can beput on cases or pallets to evaluate abuse condi-tions, Of course, if they are on the outside of afood carton, they will respond to temperaturechange more rapidly than does the bulk of thefood, so the predicted shelf life would be less thanthe period of time the food could actually last.

A different device using the gas diffusion prin-ciple, which also integrates time and tempera-ture, is available (Info-Chem, Fairfield, N.J.). Afteractivation, a gas crosses a permeable barrier inthe device to react with another chemical, caus-ing a color change along a scale. The barrierproperty controls the temperature sensitivity. TheQ 10's are: TTW -10 Q 10= 1.68; T T W-15 Q 1 0= 2 . 2 9 ;T T W-20 Q 10 = 2.88; and TTW-25 Q 10= 4.03.

A factor limiting the use of these latter devicesis that they respond much too slowly at tempera-tures below freezing, so they probably cannot beused for refrigerated frozen foods. Even at 4° C,the devices all have a response life of 750 days. Ifthe reaction rate were faster or the indicator wasmade more sensitive, they could be especiallyuseful for very sensitive refrigerated pharmaceu-ticals to indicate if the drugs have been abused byholding at high temperatures. However, the de-vices are applicable for semiperishable foodswith a shelf life of 30 days to 1 year at 15° to 38°c.

Other devices are available that integrate timeand temperature but have much shorter responsetimes. The 3-M Company (Minneapolis, Minn.) andTempil Company (South Plainfield, N. J.) have de-veloped abuse temperature/time integrators.These devices use the melting-point principle inwhich a waxy material melts at a given responsetemperature and is absorbed by a wick that devel-ops a color along a visible scale (much like a ther-mometer) as long as the device is held above thiscritical response temperature. The device doesnot integrate absolute shelf life as the other de-vices: rather, it integrates exposure to some tem-perature above a set limit. This, however, isuseful if the product has a very high Q10 (i.e., thefood is very sensitive to high temperature). Thedevices are also useful for products with a shelflife of less than 1 week.

Several studies in the past have been made totest the reliability of these time/temperature inte-grators (K. Hu, Food Technology, August 1972; K.Hayakawa, ASHRAE J., April 1974; C. Byrne, FoodTechnology, June 1976; and A. Kramer and J. Far-quhar, Food Technology, February 1976). Inessence, they have found that many of these indi-cators become unreliable if they are exposed tohigh temperature prior to activation. In addition,the response characteristics in many cases do notmatch manufacturers’ specifications.

Since these studies were published, the indica-tors have been modified, so performance may bebetter although there is nothing available in thescientific literature, However, the major problem

Appendix C— Technological Evaluation of Shelf Life of Foods s 95

is s t i l l to develop an indicator that exactlymatches the Q10 for the food if it is to be used on anindividual food package to indicate amount ofshelf life left. The Australians have devised suchan indicator that has the capability of electron-ically setting the exact Q10 desired (J. Olley, Int’1Inst. of Refrigeration, Australian National Com-mittee, Joint Meeting of Commissions, Melbourne,Australia, September 1976). The device is usefulas a research tool for monitoring a distributionsystem but is not practical for everyday use onpackages. The significance in stimulating furtherdevelopment of shelf-life devices is that they couldgive the shelf life directly and would be a majorbenefit to the consumer.

Exponential Decay Shelf-LifePrediction

As with the mechanism measuring the constantloss of shelf life, an equation can be developed topredict the amount of shelf life used up as a func-tionthattion

of variable temperature storage for foodsdecay by an exponential mechanism. Equa-12 is:

(12)

where A is the amount left at the end of the time/temperature distribution, and k,tll is as was dis-cussed for the constant-loss equation. Unfortu-nately, there are no reports in the literature fortesting the validity of this equation in the meas-urement of shelf life as has been done for con-stant loss rates for frozen foods. However, appli-cation of this equation to the calculation of qualitylosses, nutrient destruction, and microbial deathduring the thermal processing of canned foodshas been successful (M. Lenz and D. Lund, J. FoodSci. 42: 989, 1977; J. Food Sci. 42: 997, 1977; and J.Food Sci. 42: 1002, 1977). Therefore, there is noreason to believe that this equation and approachis not applicable to predicting storage life offoods.

Currently there are no devices that have a first-order response, and the zero-order devices men-tioned above should not be used for a food whichdecays by first order unless the extent of reactionwhich terminates shelf life is only a small fractionof the total reaction that can occur, Further re-search is needed in this area.

Sequential Fluctuating Temperatures

In some cases, a product may be exposed to asequential regular fluctuating temperature pro-file, especially if held in boxcars, trucks, and cer-tain warehouses. This is because of the dailyday/night pattern. Many of these patterns can beassumed to follow either a square-wave or sine-wave form as shown in figure C-8. The amount ofdeterioration occurring in this storage sequencecan be calculated by the formulas previouslypresented if the proper order of reaction is used.

There have been some papers published thathave developed formulas for calculating theamount deteriorated for either square-wave orsine-wave functions. The classic papers havebeen by Hicks (J. Coun. Sci. Ind. Research, Austra-lia 17:111, 1944), Schwimmer et al. (Eng. Chem.47:1149, 1955), and Powers (J. Food Sci. 30:520,1965). Although not stated exactly in thesepapers, the derivations they presented were allfor zero-order reactions. Unfortunately, subse-quent work by some researchers has unknowinglyused these equations for predicting changes thatoccur for first-order reactions such as microbialgrowth and vitamin C degradation. Recently,Labuza (J. Food Sci. 44, 1979) has derived the ap-plicable functions for exponential reactions, butthey have not been tested as of yet.

It also should be noted that using the mean tem-perature for either the sine or square wave topredict the loss that occurs does not give the sameresults as the actual amount of degradation. Thisis because the shelf life (or the reactions causingit) are exponentially related to temperature; thusthe actual amount of degradation is always more.

Figure C-8.—Sequential Regular Fluctuating Profile

Time

96 ● Open Shelf-Life Dating of Food

Based on this, the reaction can be assumed to beoccurring at some effective temperature that isgreater than T mean. In the same paper Labuza(1979) has derived the necessary equations.

Other Temperature Effects

Two other phenomena can occur in foods as afunction of temperature that lead to loss of shelflife—namely, staling and phase change. Staling isa process which occurs in bakery items and is re-lated to the crystallization of starch components.In staling, the rate of loss of shelf life increases astemperature decreases. The kinetics are expo-nential in nature with a Q10 of around 2 to 3. For arecent review of staling, see W. Knightly, Bakers’Digest, No. 5, 51: 52, 1977.

A second area is that of phase change includingthawing, freezing, and fat-melting—solidifyingphenomena. Although no mathematical modelscan be developed to predict how these would af-fect loss of shelf life, it is known that thawedfrozen foods are very subject to microbial deteri-oration, and the melted fat can oxidize faster aswell as cause loss in desired texture. Commercialdevices that indicate whether a frozen producthas been exposed at temperatures where it canpossibly thaw have been developed by the samecompanies that have made the time/temperatureintegrators. These are cheap enough to be used onindividual food packages and would be useful toindicate abuse. However, a major drawback isthat the device could melt before the food doesand thus would not be truthful.

UTILIZATION OF TEMPERATURE-DEPENDENCE EQUATIONS

The previous section outlined the means bywhich equations could be used to predict shelflife, Obviously, these equations could be used toset a sell-by date in which the fraction of shelf lifeused up in the distribution/marketing systemcould be calculated. From this, information couldbe included on the package that would indicatethe expected shelf life for given storage condi-tions in the home. Similarly, the same calculationsincluding specified home storage could be used toset a use-by date. However, some of the problemsthat could occur which would make these calcula-tions meaningless are:

1.

2.

3.

4.

5.

The product used to develop the shelf-lifedata or graph may not be the final productmarketed, since the shelf-life studies shouldstart early in the product development.As in 1, the product tested may be producedin the lab or pilot plant and therefore will notbe subjected to the same conditions as wouldthe product produced in the plant.The ingredients can vary because of growthconditions, rain, sunshine, etc., as well asgenetic variety. The ingredients may also bestored for variable times.Labels must usually be made early in theyear prior to the growing season so that if ef-fects as in 3 occur, it would be impossible toaccount for them.The calculations to set the date must be de-veloped for the average conditions. Some

6

7.

products thus will be out-of-date before thetime on the label just because of statisticalvariation.

Some products may be mishandled by distrib-utors and supermarket personnel and thuscould lose shelf life before the label date.

Product shelf-life tests can only be done onindividual packages. During a large part ofthe distribution time, though, these packagesare in cartons, which in turn are in cases,which are in pallets. Therefore, exposure tothe external conditions is not so drastic—especially for those cartons in the center—and the product may have a shelf life greaterthan the label states, Good food could then bewasted.

Since other factors could also be included inthis discussion, it is obvious that setting a trueshelf-life date for each package cannot be done.Only averages can be calculated, and these onlywhere good data exist. Collecting this data is avery time-consuming and expensive process, espe-cially where sensory panel evaluations must beused. Thus, it is probably best to not require opendating of all food products but to mandate whatcan be put on the label if open dating is used.Based solely on kinetic implications with respectto temperature, a sell-by date with home-storageinformation or a best-if-used-by date seems mostlogical.

Appendix C— Technological Evaluation of Shelf Life of Foods ● 97

MOISTURE EFFECTS ON SHELF-LIFE PREDICTIONS

Moisture Gain or Loss Equationto Reach Critical Value

Moisture gain by dry or semidry foods can leadto several modes of deterioration, including mi-crobial growth, loss of crispness, loss of softness,hardening, and caking. The moisture gain or lossfor a food held at constant temperature and ex-posed to a given external relative humidity can bepredicted from simple engineering relationshipsas reviewed by Labuza et al. (Trans. ASAE 15:150, 1972). The basic equation 13 is:

P out = vapor pressure outside the packageP in v a p o r p r e s s u r e inside the package— I e , the

vapor pressure of water from the foodA = package surface area

As with temperature, an increase in externalhumidity conditions would decrease the time itwould take for a given packaged dry food to reachthethat

●

●

●

●

●

undesirable moisture content. The factorswould be needed to predict this time include:The moisture absorpt ion isotherm as infigure B-1.The package film permeance k/x. Manufac-turers usually list a range of values for agiven packaging film. However, actual val-ues can be obtained by simple tests.The ratio of the package area (A) to dryweight (Ws) contained,The initial moisture content mo and criticalmoisture m o above or below which oneshould not go. The critical moisture me—thepoint of unacceptability—must be foundfrom studies of the food at different mois-ture.The relative humidity and temperature towhich the product will be subjected, Fromthis and the isotherm equation me, the mois-ture content the food would achieve if it hadno package can be found. In addition, thevalue of the vapor pressure of water (Po) atthe temperature of the test can be obtainedfrom standard tables.

Given these values, equations 14 and 15 can befound, which give the time (0) to reach a certainmoisture content (m). The exponential term ofmoisture is plotted as a function of time in figurec-9.

Figure C-9.— Moisture Gain

r ivv I

I

“,

1 2 3 4 5 7 9 10 11 —

e (time) OS

As indicated in figure

(14)

(15)

C-9, if condition III werethe actual food-package system, storage undercondition I would decrease the time to reach thecritical moisture by a factor of 11-2, or 5.5 times.This would occur if the film used had 5.5 timesgreater water permeability. The same acceler-ation in loss of shelf life would occur if the prod-uct were stored at a temperature that would raisethe vapor pressure of water (Po) by 5,5 times. At100-percent relative humidity, the vapor pressureof water ranges from about 17 mm Hg (at 20° C) to72 mm Hg (at 45° C). Therefore, a decrease in theloss of shelf life of about 4.5 times would occur ifthe product were stored at the higher tempera-ture and same relative humidity.

Food package size also can affect shelf life withrespect to moisture gain. Since the ratio of pack-age area to food weight contained (A/W,) de-creases by one-third R (where R is the average

98 ● Open Shelf-Life Dating of Food

radius), a package of smaller size has a shortershelf life as compared to a larger one.

In practice, in testing for shelf life of foods, re-searchers use a combination of higher humidity(percent RH) and temperature (T) than the foodwould normally be subjected to. Most food proces-sors suggest, for dry foods, that the average tem-perature/humidity during distribution is 21° C at50-percent RH and thus apply some factor bywhich the food shelf life under the adverse condi-tion is multiplied by to give the average shelf life,

Using this method and equation 13, the shelflife of a food for which the mode of deteriorationis moisture gain or loss can be predicted if the ex-ternal conditions of distribution and marketingare presumed to remain constant. However, in thereal world, the humidity can vary as well as thetemperature, Fluctuating temperature effectswere discussed previously. In general, higher hu-midities are associated with higher temperature,but no exact pattern of correlation exists. For ex-ample, if a T/percent RH distribution were knownas in figure C-10, the time 0 to reach a givenchange in moisture would have to be calculatedby breaking up total time into n small AOl parts.For each AO, a Ti and percent RHi could be readoff the graph. Then to get the change in moisturefor that segment of time (starts at mi and ends at

● Determine the vapor pressure P o f r o m astandard table.

● Derive a new me from the isotherm for thenew external percent RH i. If me is less thanm i at A@i$ the loss equation would be used; ifit is greater than m i, the gain equation isused,

From these steps, the value of m as a function oftime could be calculated, and thus 0, could befound, These calculations, in fact, could be usedto predict the net-weight losses of cereals andflour under given variable external conditions—another currently controversial regulatory issue.

Constant Weight Loss Prediction

Two situations exist in which a more simplifiedversion of weight loss can be derived: 1) loss ofmoisture from frozen foods and 2) loss of moisturefrom fresh produce such as meats, fish, vegeta-bles, and fruits, In both cases, a constant externalhumidity and constant temperature are assumed,based on the fact that either frozen or refriger-ated storage is used. The solution for both situa-tions is based on equation 13.

Figure C-10.—Storage Conditions

Given that k/x, the area A, the external humidi-ty and P out are constant, the question is to deter-mine if P in is constant. By definition, Pin is thevapor pressure of water in the food. For a frozenfood, P in is determined solely by the temperaturethat pure ice would have at the storage tempera-ture and thus could be read from a standardtable. Since fresh produce have moisture contentsin the range of 60 to 98 percent and the loss ofweight to reach an unacceptable quality is notlarge, the vapor pressure pin is equivalent to thatfor liquid water at the storage temperature. Thusequation 13 becomes equation 16:

If mc is the critical moisture content as set by net-weight limitations or by quality and m i is the ini-tial moisture for a package containing W, gramsof dry solids of a food, the time to reach end ofshelf life is determined by equation 17:

This equation could be used to predict how long afood would last for certain conditions. For exam-ple, for a vegetable like celery in a package forwhich we would want 12 weeks of shelf life beforeit lost enough water to lose crispness, at a refrig-

Appendix C— Technological Evaluation of Shelf Life of Foods “ 99

erated storagecould prevail:

P in =P o u t =

.“. A p =

If the celery

of 5° C, the following conditions

654 mm H g80 percent R H X 6.54= 523 mm HgnormaI condition of storage1.31 = 654 - 523

had an initial moisture content of95 percent and there were 10 ounces in the bag,the dry weight W s would be 14 grams. Celeryloses its crispness when it loses about 5 percent ofits weight in water (mc = 18; mi = 19). Using poly-ethylene with a k/x = 1 and a bag of 0.1 m 2, theshelf life would be about 3 months based on waterloss, thus achieving the 12 weeks, Of course, inthis time, microbial growth could decay the food.

The realistic problem is defining some criticalmoisture content for the particular food. In reallife, both temperature and humidity vary: thus aniterative procedure as described earlier must beused based on a constant weight loss by equation16 for each of these periods.

Moisture Change for ConstantExternal Temperature and

Humidity Conditions

In a classic research endeavor, Karel andLabuza developed the mathematical techniquesthat combined the equations for prediction ofmoisture change with the reaction kinetics ofvarious modes of deterioration as a function of aw

(Air Force Contract F 41-609-68-C-0015, February1969, Optimization of Protective Packaging ofSpace Foods). These theories were tested in detailby Mizrahi et al. for predicting loss of shelf life ofdehydrated cabbage undergoing nonenzymaticbrowning by a zero-order mechanism (J. Food Sci.35:799, 1970, J. Food Sci. 35:804, 1970). The re-sults were extremely satisfactory.

The basic steps needed to be able to predictend of shelf life under these conditions are:

●

●

Store the dehydrated product at several con-stant temperatures and various relative hu-midities and measure extent of deteriorationwith time. Much data like this is available inthe literature for dehydrated foods, especial-ly concerning vitamin loss. At least three hu-midities (aw 's) are required. The reactionorder must be determined.Decide what extent of deterioration is con-sidered to be unacceptable. Plot the log ofthe time to reach this extent for constanttemperature versus the aw of the product as

in figure C-11, Generally, a straight lineabove the monolayer water activity shouldbe obtained at constant temperature.Using either the moisture gain or loss equa-tion and proceeding step by step as previous-ly described, predict the moisture contentchange as a function of time for some con-stant external temperature and humidity(figure C-12).Using the m versus 0 graph, divide the timeinto small AO segments (figure C-12) a n dmeasure the average moisture content in thistime period.For each moisture content and temperature,calculate the change in quality using thepreviously developed equations.

As noted, these steps have been tested andfound to be very good in predicting shelf life,Mizrahi and Karel (J. Food Sci. 42:958, 1977) haverecently shown that this procedure can be simpli-fied by storing the food in a very permeablematerial at a given high-relative humidity and

Figure C-II .—Shelf Life as a Functionof aW and Temperature

1 1 I I I0.2 0.4 0.6 0.8 1.0

Water activity

100 . Open Shelf-Life Dating of Food

Figure C-12.–Calculated Moisture Content v. Time

comparing the extent of degradation to any othercondition by a ratio method. As in the above solu-tions, this assumes constant external tempera-ture and humidity.

Moisture Change Under VariableExternal Temperature and

Humidity Conditions

The previous section described predicting theloss of shelf life for constant external humidity

conditions. The same procedures can be used tocalculate the extent of reaction for variable tem-perature and humidity conditions applying thekinetic derivations as a function of temperaturefrom the section “Shelf-Life Prediction for Vari-able Temperature. ” The first step would be calcu-lating the moisture content as a function of timefor a variable time/temperature/humidity distri-bution as previously shown. Then, applying eitherzero- or first-order kinetics, the extent of degrada-tion is calculated for small time segments knowingthe moisture content, aw, temperature, and exter-nal relative humidity at that point.

Although this is the real world situation, noliterature exists that has tested this idea, so it isnot known how good the predictions would be forestimating a shelf-life date that could be used on afood package. Even more critical is the fact thatthe external humidity distribution is even lesswell-known for food systems and is not as easilypredicated as is the external temperature distribu-tion, Therefore, only rough estimates can be madeof the actual loss of shelf life.

Of course, another way that this could be con-trolled would be to use a pouch with a very lowwater permeability, thereby eliminating the mois-ture-change problem. This could extend food shelflife, but at the expense of using more preciousraw materials (petroleum, aluminum, etc.) and atgreater cost to the consumer, It is this tradeoffthat the consumer must make in terms of food pur-chase—that is, a longer guaranteed shelf life at agreater cost, or a possible out-of-date food atlower cost. In addition, no devices exist that canintegrate time/temperature/humidit y condi t ionswith respect to shelf life,

OXYGEN EFFECTS ON SHELF LIFE

Introduction

oxygen availability is another factor that canaffect the time to reach end of shelf life and thusthe open date put on a food package. Several re-actions in which the rate is a function of oxygenavailability include:

● microbial growth,● senescence of fruits/vegetables,● browning of fresh meat,

● rancidity (lipid oxidation), and● vitamin C deterioration.Very little information is available on the use of

shelf-life prediction equations with respect to oxy-gen as well as temperature and moisture content.Karel (Food Technol. 28:50, 1974) has reviewedthis area. Part of this void is caused by the dif-ficulty in 1) designing simple equipment to controloxygen levels during experiments that utilize oxy-gen as one parameter and 2) measuring and con-trolling oxygen in food packages,

Appendix C— Technological Evaluation of Shelf Life of Foods ● 101

Fruit and Vegetable Senescence

Once fresh produce is harvested, it continuesits biological processes of drawing upon internalstarch and sugar stores for an energy supply.This will continue until the supplies are depletedor the buildup of breakdown products affects thetissue in such a way that spoilage or microbial at-tack occurs. This rate of biological reactivity is afunction of oxygen availability in terms of oxygenpressure as described by figure C-13. As seen, thelower the oxygen pressure (PO 2), the lower therate of oxygen uptake via respiration, or con-versely, the lower the rate of loss of stores. Thus,a low PO 2 will give a longer shelf life. Unfortunate-ly, below a certain PO 2 level, an anaerobic proc-ess of incomplete breakdown occurs in whichacids and alcohols are produced that also destroythe food quality. Thus, a lower limit exists.

Some fresh produce is preserved using thisprinciple of limiting oxygen availability by: 1)holding under partial vacuum (hypobaric stor-age), 2) flushing the truck or storehouse with ni-trogen to force out the oxygen, or 3) flushing andsealing in a semipermeable pouch, In addition,C O2 may also be added. This slows the rate of ox-idation by mass action, since CO2 is a product ofthe oxidation process. Jurin and Karel (FoodTechnol. 17:104, 1963) have done some of theclassic work in this area, They showed that theshelf life of a food in a pouch can be predictedgraphically.

Figure C-1 3 .—Senescence Rate as a Function of O2

r* >

Partial oxygen pressure PO,

Basically, figure C-13 illustrates this concept.The graph is constructed from data of respirationrates; then the equation for gas permeation intothe pouch is drawn on the graph.

Since the external oxygen pressure essentiallyremains constant, except as one travels up ordown a mountain or in a plane, the rate of oxygenpermeation is a constant. Thus, the rate as a func-tion of the internal oxygen level is a straight line,which can be superimposed over the oxygen up-take graph as in figure C-14. Lines A and B repre-sent two different films of different oxygen per-meability.

Figure C-14 can be used to illustrate whatwould happen if a product were packaged in afilm with a permeability described by A and at aninitial oxygen partial pressure P,. Initially, oxygenflow into the pouch is greater than uptake, so oxy-gen pressure rises, slowing the flow and increas-ing the uptake. At some point, the two rates areequal—that is, the flow rate just matches thereaction rate. In other words, the package will re-main at some constant internal oxygen level andthe uptake will become constant. If the total ox-ygen uptake to reach end of shelf life is known,the shelf life can be easily calculated by dividingthe total uptake by the constant rate.

To increase shelf life, all one has to do is lowerthe film permeability such as seen for B, ensuringthat the new oxygen level is not below the pointwhere anaerobic glycolysis occurs. This methodhas been put into practice with much success, butfew film types are available with sufficiently lowoxygen permeance to be able to control shelf lifeto the desired value. Most oxygen-impermeablefilms also retain moisture that tends to inducemold growth on the product surface. In addition,most data is at a single temperature. Since the Q10

for respiration is about 2 to 3, data must be ana-

Figure C-14.— Rates of Permeation andRespiration of O2

R**

B

102 ● Open Shelf-Life Dating of Food

lyzed as a function of temperature also, utilizingthe techniques described previously.

Rancidity

Labuza (Critical Reviews of Food Technol. 3,1977) reviewed the relationship of oxygen to sta-bility of foods with respect to rancidity. A situ-ation similar to that of respiration exists in thatthe oxygen uptake follows the same pattern. How-ever, there is no lower oxygen critical limit—thelower, the better, in fact—and CO2 does not slowthe reaction.

Simon et al. (J. Food Sci. 36:280, 1971) was thefirst to apply this to oxidation of a dehydrated

shrimp product using the same type of mathemat-ical and graphical analysis. Karel’s group (J. FoodSci. 37:679, 1972) did a more in-depth study inwhich moisture was also simultaneously diffusinginto the package for potato chips stored at con-stant temperature and external humidity. Veryelegant computer-based solut ions were pre-sented. However, the time to develop the neces-sary data for equation development for mostfoods would be far in excess of that desirable inshelf-life testing or product development.

Basically, it can be stated that methods can bedeveloped to predict the end of shelf life whencaused by oxygen-sensitive reactions that also de-pend on aW and temperature.

Status of

Appendix D

Open Shelf-Life DatingRegulations for Selected Countries

and International Food LabelingOrganizations, 1978

Country/organization

BRITISH COMMONWEALTH

United Kingdom CodeI r e l a n d Code or openI n d i a . Code or openAustralia Code or openNew Zealand Code and open

EUROPEAN

Netherlands Open

Swi t ze r land Code or open

S w e d e n OpenG e r m a n y Code and openYugoslavia CodeU S S R Code

ASIATIC

Japan Code in Arabicor Latin

T h a i l a n d CodeIraq ., ––

I s r a e l Code or open

LATIN AMERICAN

M e x i c o Code or openC o s t a R i c a Code or pack

dateVenezuela. Code or openArgent ina Code or lot no.B r a z i l Code or lot no

AFRICAN AND OTHERS

PhilippinesE g y p t

N i g e r i a

Date display

Code or open datea Type of date Day/month/year Month/year only

Open date recommended for short life, 6 months only s 3 months > 3 monthsNo guidelinesNo guidelines —— For codeOpen date recommended for short life, < 90 days ~ 3 monthsRequired for some products Pack ~ 3 months > 3 months

Determined for each product by Commodi ty Board ––Recommended for short-life, cold-stored productsRecommended for most milk, meat products; frequently ––more than one date used voluntarilyRequired for short-life, cold-stored products ——

For milk products and others with shelf life < 1 yearOpen pack date requiredRequired only on secondary container Pack or use-by

Open date recommended for some milk, meat, and fish ––productsOpen date voluntary, used for some products ——

WiII conform to Codex Alimentarius--on exports — . Day/month re-quired if code

Use-byUnder consideration

No requirements for open datingNo requirements for open dating

Use-by——— .

No specific requirements or guidelinesInspect all exports for conformance with importingcountry regulationsConform to requirements of importing countries to extentlocal facilities allow ——

For codeFor code

aaold Ila{lc type )ndlcales mandatory rewlrefneflfs

103

104 • Open Shelf-Life Dating of Food

—Country/organization

Libya

INTERNATIONAL

CodexAlimentarius.

EuropeanEconomicC o m m u n i t y .

Central AmericanEconomicC o m m u n i t y ,

Code or open datea Type of date Day/month/year.—

Code or open Conform to requirements of importing countries to extentlocal facilities allow

ORGANIZATIONS

Code or open Open dating required for baby food

Open ——

Code or open Pack

Open dating required for all products

Best-if-used-by

c year

Month/year only

> year

aB~lfj Ila[lc type Iruirates mrrdalov rwulwmmSOURCE OTA Survey

Appendix

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