Nutrition Communication Award

General Foods Limited announced the third annual $1,000 Nutri­tion Communication Award for excellence in writing and broadcastingon nutrition. For the first two years, the General Foods Nutrition Com­munication Award was confined to print. This year in response to thebroadcasters, the inclusion of a radio category is announced. Print and ra­dio will be judged separately, each on its own merits and with its ownpeers.

Columns, new stories, features, interviews, dialogues, etc., devoted tonutrition for the Canadian public, published or broadcast during calen­dar 1976 are eligible for this award. The entries may be in English orFrench, and they will be assessed by an independent panel of judges. Thedeadline for submissions is January 17, 1977, with the winners being an­nounced two months later. Entry rules may be obtained from U. Abra­hamson, General Foods Limited, Box 4019, Terminal A. Toronto, Ont.

CURRENT CONCEPTS IN THE IDENTIFICATION OF STAPHYLO·COCCUS A UREUS IN FOODS

M. K. RAYMANDr. Rayman is with the Bureau of Microbial Hazards, of the Health Pro­tection branch in Qttawa. The following is the text of a paper presentedrecently to the Guelph Section CIFST. Ed.

Staphylococcal food-poisoning represents one of the major problemsin the food industry. Figures compiled by the Centre for Disease Control,Atlanta, show that of the etiologic agents known to cause food poisoningin the United States, Staphylococcus aureus is the major causative organ­ism. The illness occurs when a susceptible individual ingests enterotoxinsproduced by the organism. Symptoms are mainly diarrhea and vomitingwithin 2 to 6 hours of consumption of the contaminated food. Normally,the illness lasts for a few hours, usually not longer than a day.

It is estimated that about 50% of the human population carry S.aureus in the nose and on the skin; it is therefore very difficult to avoidcontamination of food by this organism. On the more optimistic side, it isestimated that a population of about one million cells per gram of food isrequired to produce sufficient enterotoxin to cause illness in man. Whilethis level of contamination will not normally be introduced into a food,one should not be lulled into a false sense of security, for even at very lowlevels of initial contamination, if conditions are favourable for multiplica­tion of the organism, one million cells per gram can be attained within 3to 5 hours. To avoid growth of the organism, we recommend that foodsbe held at 4°C (40°F) or lower if they are to be served cold or 60°C(140°F) or higher if they are to be served hot.

The ideal procedure for diagnosis of staphylococcal food poisoningis analysis for the presence of enterotoxin in the suspect food. A numberof serological assays has been developed, but because of the complicatedprocedures of concentration and purification of the food extract, thistechnique is costly and time-consuming for quality control purposes.

The determination of viable S. aureus in a food product is morepractical for control laboratories. The procedure involves plating a por­tion of the sample on a selective medium which allows growth of S.aureus and suppresses growth of other microorganisms. Several selectiveand diagnostic media have been developed, but not all of these mediasuppress the growth of all non-So aureus organisms. For this reason, con­firmatory coagulase tests are conducted on a proportion of the coloniesgrowing on the selective medium. In this test, coagulation of plasma is re­garded as positive identification of S. aureus, and unless the sample is in­volved in a food poisoning outbreak, additional tests to detect enterotoxinproduction or phage typing of the organism are not routinely performed.Therefore, much emphasis is placed on the coagulase test in confirmingthe presence of S. aureus in a food. The coagulase reactions are scoredprogressively I + through 4 + depending on the extent of clotting of theplasma. Unfortunately, because of the subjective nature of this test, in­consistencies arise at this stage of the analysis. Examples of these incon­sistencies are as follows: in the procedure of the Association of AnalyticalChemists for the isolation of S. aureus from foods, any degree of clottingof plasma is regarded as positive evidence of coagulase production. Weregard a 2 + or greater reaction as evidence of coagulase production. AI + reaction we read as a negative test. Recently a group of researchers inthe United States concluded that only 4 + coagulase reactions can be con-

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sidered positive identification of S. aureus. Their belief is that culturesyielding I +, 2 + or even 3 + reactions warrant additional testing forcharacters such as glucose and mannitol fermentation, thermostable nu­clease production, and/or lysostaphin sensitivity before the organism isconfirmed as S. aureus.

Because of this obvious variation in the interpretation of the coag­ulase test, we conducted a study to evaluate the coagulase test as a crite­rion for the identification of S. aureus.

Cultures used in the study were isolated from foods and clinicalcases. Those from foods were grouped into 3 categories: (a) serologicallyconfirmed enterotoxigenic strains of S. aureus isolated from foods in­volved in food poisomng outbreaks; (b) staphylococci isolated from foodsduring routine microbiological analyses and which have been tested forenterotoxin production by the micro-slide-gel double diffusion technique,and (c) isolates from foods presumed to be coagulase positive staphylo­cocci and which have not been tested for enterotoxin production.

The clinical isolates were obtained from the Laboratory Centre forDisease Control, Ottawa.

With the exception of I of 63 enterotoxigenic isolates in category (a),there was a complete correlation among coagulase and thermonucleaseproduction and the ability of the cultures to produce acid from glucoseand mannitol under anaerobic conditions. The same was true for 103clinical isolates. The coagulase reactions of these cultures were mainly4 +, about 25% yielding 3 + reactions. Of the isolates in category (b), 37cultures yielding 3 + and 4 + coagulase reactions were also positive forthermostable nuclease production and were capable of anaerobic utiliza­tion of glucose and mannitol. Only I of 9 isolates which clotted plasma atthe 2 + level was capable of producing acid from glucose and mannitoland these isolates were all negative for thermostable nuclease productionas were 7 cultures which yielded I + coagulase reactions. Further investi­gation of this phenomenon using isolates in category (c) revealed that 203isolates yielding I + coagulase reactions were all negative for thermos­table nuclease production; only 10 of 261 isolates yielding 2 + coagulasereactions were positive for thermostable nuclease production; only I of53 isolates yielding 3 + coagulase reactions was negative for thermostablenuclease production; and 33 isolates yielding 4+ coagulase reactionswere all positive for thermostable nuclease production.

These results indicate that the correlation between thermostably nu­clease and coagulase production holds true only for those cultures ielding3 + or 4 + coagulase reactions. Cultures yielding 2+ or lower coagulasereactions are invariably negative for thermostable nuclease production.

If we accept the observation that coagUlase-positive staphylococciare, with only a very few exceptions, positive for thermostable nucleaseproduction as outlined in the 8th Edition of Bergey's Manual, then wehave to conclude that the majority of cultures yielding 2 + coagulase re­actions should not be regarded to be S. aureus unless they have beenshown to be positive for thermostable nuclease production or are capableof producing acid from glucose and/or mannitol under anaerobic condi­tions.

The thermostable nuclease test is less subjective than the coagulasetest in that a positive reaction involves a change in colour of the mediumfrom blue to bright pink. In addition, it is inexpensive, rapid and simpleto perform. These advantages make it tempting to suggest that the coag­ulase test be replaced by the thermostable nuclease test in the routine ex­amination of foods for the presence of S. aureus. This suggestion mightbe premature at the present time, because at least one of a limited num­ber of enterotoxigenic strains of S. aureus in our survey failed to producea thermostable nuclease. A larger number of strains of S. aureus and awider range of bacteria must be tested for thermostable nuclease produc­tion to ensure that the test is indeed specific for S. aureus. In the mean­while, we would recommend that the thermostable nuclease test be per­formed on all cultures yielding 2 + or lower coagulase reactions beforeclassifying them as S. aureus.

Others in the U.S. have used the thermostable nuclease test as an in­dicator of growth of S. aureus in foods. The method is essentially thesame as for isolated organisms except that the actual food sample is usedafter first being placed in a boiling water bath or steamed to destroy heatlabile nucleases. The method requires only 4 to 6 hours to complete com­pared with several days for the cultural technique.

Another important advantage of the thermostable nuclease test is itsuse in the examination of heated and/or fermented foods where viablecells of S. aureus could decline in numbers to undetectable levels whileboth the nuclease and enterotoxin, because of their heat stability can stillbe detected in the foods. A word of caution, however, the method is onlyuseful for detecting large populations of S. aureus in foods (> 10' per g)and as such, would be inappropriate in a quality control laboratory where

J. Inst. Can. Sci. Technol. Aliment. Vol. 9, No.4, 1976

J. M. deMan.Department of Food Science,

University of Guelph.

a population of 100 or more cells of S. aureus would be considered unac­ceptable. The method is most useful in monitoring foods suspected ofbeing involved in food poisoning outbreaks.

Recently, the test for nuclease activity has been modified to includean extraction step. This involves blending of the sample with water, cen­trifugation and treatment of the supernatant with cold trichloracetic acid.The usefulness of this extraction step has yet to be determined.

OTHER JOURNALSJOURNAL OF FOOD BIOCHEMISTRY

The Journal ofFood Biochemistry, a new quarterly journal edited by Prof.Herbert O. Hultin, University of Massachusetts, will provide an inter­national means of communication of recent progress in all aspects of foodbiochemistry. Both full length papers and short notes of original research,as well as review articles will be published. This journal is devoted tooriginal research on the effects of handling, storage, and processing onthe biochemistry of food tissues and systems, and will serve as a focalpoint for all disciplines that bear on the problems of food biochemistry.The emphasis of the journal will be on the description of changes ofchemical constituents, enzymes, and cellular structures and on the mecha­nisms that control these events.

The journal will stress the application and relevance of enzymechemistry and technology, membrane biology and chemistry, cell biology,biophysics, genetic expression, and phytopathology to postharvest, post­mortem and processmg problems dealing with foods. Vol. I, No. I willappear January 1977 at $45.00 per volume including shipping charges inNorth Amenca. SubscnptlOns may be placed wah: Food & NutritionPress Inc., 265 Post Road West, Westport, Conn. 06880, U.S.A.

JOURNAL OF FOOD PROCESS ENGINEERINGThe Journal of Food Process Engineering, a new quarterly journal editedby Prof. Dennis R. Heldman, Michigan State University, exists to meetseveral needs. The purposeof this journal is to provide a focal point forpublication of research dealing with the engmeenng aspects of equipmentand process design needed in the food industry. Original full length pa­pers and review articles, as well as short notes of original research will bepublished. The publication of basic and applied research will be encour­aged in the journal. Research manuscripts dealing with any engineeringaspect of post-production handling, storage, processing, packaging anddistribution of food will be accepted. Due to emphasis on processes anddesign, articles will mclude results on properties of processed foods asso­ciated with transport of products, as well as with food texture. Researchresults dealing with thermal properties of processed food as needed in de­sign of processing equipment will be emphasized.

Manuscripts dealing with analysis of process engineering operationssuch as freezing, evaporation, dehydration, equilibrium and mechanicalseparation, and packaging, as well as equipment cleaning and sanitationwill be encouraged. Vol. I, No. I will appear January 1977 at $45.00 pervolume including shipping charges in North America. Subscriptions maybe placed with: Food and Nutrition Press, Inc., 265 Post Road West,Westport, Conn. 06880, U.S.A.

JOURNAL OF FOOD PROCESSING AND PRESERVATIONThe Journal ofFood Processing and Preservation, a new quarterly journaledited by Prof. Theodore P. Labuza, University of Minnesota, will coverthe broad areas of chemistry, physical chemistry, microbiology, and engi­neering of food systems with respect to processing and preservation. Orig­mal full length papers, short notes of original research, review articles,and a section devoted to the physical and chemical properties and engi­neering data of food materials will be published. The papers will coverthe latest knowledge and advances in processing and preservation with abalance between fundamental aspects and applied food processing proce­dures. Articles will deal with an in-depth analysis of new principles andprocesses of interest to food scientists and technologists, and to the foodindustry. Review articles of current interest in food processing and pres­ervation will be accepted.

It is envisioned that the section on research notes will contain infor­mation on methodology and studies that were not successful or com­pletely successful which will aid future investigators. The journal will alsohave book reviews of pertinent new books, and as needed a section oncurrent legislation involving changes in processing and preservation prac­tices. Vol. I, No. I will appear January 1977 at $45.00 per volume includ­ing shipping charges in North America. Subscriptions may be placedwith: Food and Nutrition Press, Inc., 265 Post Road West, Westport,Conn. 06880, U.S.A.

Can. Inst. Food Sci. Technol. J. Vol. 9, No.4, 1976

FOOD CHEMISTRYA new journal, edited by Dr. G. G. Birch and Mr. L. F. Green, Na­

tional College of Food Technology, Surrey, England. It is concernedmainly with the chemistry and biochemistry of foods and chemical andbiochemical changes occurring in foods. It is also concerned with sensoryand nutritional properties of food within a chemical or biochemicalframework. The journal is designed to provide a vehiCle for the widestpossible dissemination of knowledge in food chemistry, mainly on re­search papers and reviews.

Volume I No. I appeared in July, 1976 at $20.00 for the two issuevolume inclusive of postage. Subscriptions may be placed with: AppliedScience Publishers Ltd., Ripple Road, Barking, Essex, England.

BOOK REVIEWSBASIC FOOD CHEMISTRY, by F. A. Lee, 430 pp. 1975. The AVI Pub­lishing Company Inc., Westport, Conn., U.S.A.

For many years there has been a scarcity of textbooks on food chem­istry. The few existing books were unsuitable for several reasons, mostlybecause they contained only a small amount of material that can be clas­sified as food chemistry. Basic chemistry and biochemistry, food process­ing and food analysis take up major portions of these books. Basic FoodChemistry by Lee has the same shortcomings. Too much of the materialin the early chapters is basic chemistry and biochemistry and would con­stitute repetition for students in food chemistry courses. The commodityoriented chapters in the last half of the book would be more suitable for acourse in food processing.

FOOD FOR LIFE, by F. E. Deatherage. 1975. Plenum Press, New Yorkand London. $19.50.

Introductory courses in food science for both majors and non-majorsin food science have become popular in many universities in NorthAmerica. An increasing number of textbooks specifically written for thistype of course has appeared in the last few years. It is a great help toteachers and students when a selection of good textbooks is available.These texts reflect very much the interest and background of the authors.This one is no exception. Food for Life places a heavy emphasis on biol­ogy. I question whether this is desirable in a book mainly directed to stu­dents who are not science majors. However, the book is well written,contains a wealth of interesting material and constitutes a valuable addi­tion to the range of textbooks in food science.

J. M. deMan.Dept. of Food Science,

University of Guelph

SECTOR ANALYSIS-THE FOOD PROCESSING INDUSTRY, by Y.Gribowsky, 1975. Published by the Ontario Ministry of Industry andTourism. 137 pp.

This document, as stated in the introduction, attempts to identify theneeds of the food processing industry in Ontario, to establish commonobjectives and to present some industry suggestions for achieving these.The report is the result of an in-depth study of the food processing indus­try which represents about 40% of the Canadian total in terms of value ofshipments. It presents a clear picture of the extent and location of the in­dustry, of some of the problems encountered and an outlook for furtherdevelopment. This publication will be of great value to all those who havean interest in the food industry in Ontario.

J. M. deMan.Dept. of Food Science,

University of Guelph

PROCESSED MEAT TECHNOLOGY. E. Karmas. Noyes Data Corpo­ration, Park Ridge, New Jersey. 1976. 283 pp. $39.00.

This is the second volume in a series of three which have been col­lated from US patents since 1960. The first dealt with fresh meat tech­nology while this volume covers processed meat products (excludingsausage products which will be covered in volume three). The author'scontribution, apart from simplification of the legal terminology in theori~nal patents, consists of introductory paragraphs in each section. Themajor topics included are meat curing, water bmding capacity, restruc­tured and reconstituted meats, smoking, thermal processing and dehy­dration. In general, the methods described in the patents have a greatercommercial feasibility than those described in the previous volume on

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