MANUFACTURING AND MARKETING A MEXICAN-TYPE

CHEESE IN WEST TEXAS

by

JAMES RAY ROBERSON, B.S.

A THESIS

IN

DAIRY INDUSTRY

Submitted to the.Graduate Faculty of Texas Technological College

in Partial Fulfillment of the Requirements for

the Degree of

MASTER OF SCIENCE

Approved

Accepted

May, 1969

*'^"'*' — • ^ ^ i ' — - ^ g j . _ -'--•"•"•'T'w-Tr- -T iTiMir

805

1969 rVo, / I9

Cop' Z

ACKNOWLEDGMENTS

The author expresses a sincere appreciation to

Dr. M, L, Peeples for his interest, encouragement, and

technical assistance in compiling this material; to Dr.

J. J. Willingham for his assistance; to Dr. Mina Lamb

and Mrs, Clara McPherson for their helpful contributions

and suggestions.

The author also wishes to express his sincere

appreciation to his wife. Gay, for without her assist­

ance, encouragement, and understanding this study would

not have been possible.

ii

3?

TABLE OF CONTENTS

ACKNOWLEDGMENTS jj

LIST OF TABLES iv

LIST OF FIGURES V

CHAPTER

I, INTRODUCTION 1

II, LITERATURE REVIEW 3

III. SCOPE OF INVESTIGATION 23

IV. PROCEDURE 24

Procedures for Analysis 25

Manufacturing Procedures 30

Detailed Procedure for Making Mexican

Cheese 31

Evaluation by Panelists 35

V. RESULTS AND DISCUSSION. . 39

Type of Equipment 39

Cooking Temperature ' • • . • 46

Addition of Rennet . . . . . 50

Variations in Type of Milk Used 53

Variations in Salting Procedures , , . , 57

Types of Organisms Used in Cultures. . , 58 General Composition of Cheeses Prepared . • • • . . . • • . • . • . • 59

iii

, f,f «*--

Iv

Composition and Evaluation of a Mexican Cheese Marketed in Local Supermarkets, , . 65

General Observations Concerning the Experiment , . . , 66

VI. SUMMARY 68

VII. CONCLUSIONS 71

LIST OF REFERENCES 73

\

LIST OF TABLES

TABLE

1* P o p u l a r Cheese s i n Var ious L a t i n American Countries • • « . 5

2, Composition of Queso Del Pais With Varying Amounts of Glacial Acetic Acid 10

3, Make-Sheet Used by Kraft in the Manufacture of Queso Nata • . • • • • • . • 18

4, Composition of Mexican Cheese Prepared by Different Methods and Milks . 60

LIST OF FIGURES

FIGURE

1, Typical Queso de Vaca patty as marketed in Mexico . « . , , , . . 16

2, Queso Nata as found in market places in

Mexico . « . . * . . , . . . . 16

3, Mixing starter thoroughly with milk 34

4, Adding rennet in the making of Mexican cheese • • • • # . . , . , , , 34

5, Cutting of curd. 36

6, Mexican cheese after draining whey 36

7, Salting of Mexican cheese. 37

8, Hooping of Mexican cheese. 37

9, Equipment used in paraffining Mexican cheese . 38

10. Spherical molds used to form Mexican cheese weighing approximately five pounds 41

11. Bandaged cylindrical mold with dimensions of 4% inches by 18 inches 41

12. Experimental cylindrical mold made from rolled, galvanized metal ' « . . . 42

13. Pressing of Mexican cheese in experimental mold . « • . • • • 42

14. Sliced Mexican cheese patty after pressing in experimental mold • • • • • • .44

15. Pressing of Mexican cheese in spherical

molds. • . • « • , , , « * • 44 ,

16. Paraffining of spherical Mexican cheese, . • , 45

17. Fresh Mexican cheese manufactured by Harper's method. Large mechanical openings indicate whey retention 51

vi

f

vii

FIGURE

18, Mexican cheese manufactured by Harper's method showing reduced volume following leakage of free whey after storage , , , , , . 51

19, Fresh Mexican cheese manufactured by experi­mental method. Note fewer mechanical openings • • , • , . . , • • • , , , , . , , * 52

20, Experimental Mexican cheese after storage. No decrease in volume has occurred , . , « , . 52

«

CHAPTER I

INTRODUCTIOr;

For centuries a Mexican cheese commonly known as

••Queso Blanco" has been popular in Mexico and other Latin

American countries. The cheese is bland, white, and is sold

in a fresh state similar to the way cottage cheese is mar­

keted in the United States.

The manufacturing procedure for *'Queso Blanco" is

similar to that used for cottage cheese manufacturing in that

cultures of Streptococcus lacti s and solutions of rennet ex­

tract are used to coagulate mi Ik at 86-94*^ F. The major

difference between cottage cheese and "Queso Blanco" is that

the latter is sold as a pressed product, rather than in curd

form.

There is a potential demand for the product in Texas

because of the increasing Latin American population, and be­

cause people in this state have traditionally preferred mild

cheeses. Furthermore, the dairy industry in Texas is made

up largely of market milk and ice cream plants, and practi­

cally all of them are equipped to manufacture fresh cheeses.

Accordingly, the purpose of this study was to intro­

duce "Queso. Blanco," or Mexican cheese, to the Texas dairy

industry as a possible outlet for market milk, and as a

J9

p r o d u c t which cou ld p o s s i b l y f i n d favor w i th r e s i d e n t La t in

Americans in t h i s a r e a .

^i^t^fe -.

CHAPTER II

LITERATURE REVIEW

Cheese has become one of man's primary foods since

its discovery by an Asian voyager (11); and, regardless of

the type, it is a staple commodity in all countries of the

world. Many of the cheeses native to a country are shared

by other countries through the demand of immigrant popula­

tion. The more prevalent types of cheeses of foreign origin

consumed in the United States are Roquefort, Swiss, Ricotta, 4

Parmesan, Gouda, Camembert, and Neufchatel (13),

Although Cheddar cheese is the leading type of cheese

produced in the United States, seventeen other distinct types

are manufactured successfully in North America, making this

continent the leading cheese producing country in the world

at 1.9 billion pounds per year (16, 20). These cheeses may

be classified as four groups as follows:

I. Very hard (grating)

r' Ripened by bacteria

II. Hard A. Without eyes, ripened by bacteria

B. With eyes, ripened by bacteria

III. Semisoft

A. Ripened principally by bacteria

B. Ripened by bacteria and surface micro­organisms

C. Ripened principally by blue mold in the interior

IV. Soft

A. Ripened

B Unripened

The United States ranks eighth in cheese consumption at 13,8

pounds; and although consumption of the product has grown

annually, per capita figures are still far below the leading

countries of Italy and France in this respect (10).

In Central and South America, a type of cheese com­

monly called "Queso Blanco" is consumed in large quantities.

This product is marketed under several names, depending on

the type of milk used, the part of the country in which it

is produced, and the method by which it is manufactured (4),

Table 1 shows the various types of Latin American cheeses r

and the countries in which they are nov7 popular (16, 18, 23),

In the United States, a derivative of a Latin Ameri­

can cheese is produced and sold under the name, "Monterey"

cheese. According to Wilster (22), Monterey cheese was

first manufactured in California by Spanish settlers, but

was called "Queso del Pais" until David Jacks successfully

merchandised it as "Monterey Jack." However, the manufac­

turing procedure for Monterey cheese has changed consider­

ably until, today, little similarity exists between Queso

del Pais and Monterey Jack.

TABLE 1

POPULAR CHEESES IN VARIOUS LATIN AMERICAN COUNTRIES

Latin American Country Name of Cheese

Co lombia

Costa Rica

Queso Estera

Queso Oescremado Queso Huloso Queso de Bagaces Queso de Crema

El Salvador

Mexi CO

Puerto Rico

Venezuela

Queso Fresco Queso de Prensa

Panela Queso de Prensa Asadero Queso Anejo Queso de Bola Queso Enchilado Queso Nata Queso de Chihuahua Queso de Chiapas Queso de Oaxaca Queso Cotija

Queso de Puna Queso de Prensa Queso del Pais Queso de la Tierra Queso de Hoja

Queso Queso Queso Queso Queso Queso Queso Queso Queso

Fresco de Llanero de i'laracay de Perija de Prensa de Cavallo de Cincho de Mano de Cabru

Queso del Pais is a popular Latin American cheese

in Puerto Rico and is usually consumed fresh. According to •

Weigold (21), it is sold as cream cottage cheese although

it is a different product than that customarily sold in the

United States. Queso del Pais is made commercially by using

either whole or reconstituted milk. In those plants studied

by Weigold, all except one used reconstituted skim milk pow­

der, whole milk povzder, or condensed milk mixed with the

available supply of milk to increase cheese yields when

fresh fluid supply was inadequate.

In making Queso del Pais, milk that has been heated

to 180^ F is coagulated with concentrated glacial acetic

acid (USP grade) in the amount of 37.5 ounces per 1000

quarts of milk. Weigold, in a study conducted in four to

Puerto Rican plants, recommended the following procedure

for production of Queso del Pais (2l):

1. Heat milk to 85° F and clarify.

2, Pump milk to cheese vat and check acidity (which should be from 0.16 to 0,18 and never over 0,21).

3. Raise temperature to 180^ F and hold for 20 minutes,

4, Add 52 ml of concentrated glacial acetic acid diluted with 1800 ml of water per 100 pounds of milk.

5. After the curd has settled to the bottom of the vat, wait five minutes for the curd to develop a shiny, slippery con­sistency.

6. Check acidity of whey and determine the amount of neutralizer which needs to be added to return acidity to the original concentration (with sodiun bicarbonate as the neutralizer).

7. After neutralizing, remove vjhey and let curd drain for 15 minutes.

8. Add salt at a rate of 3.5 per cent of curd weight,

9. Stir curd for 20 minutes or until salt is mixed in thoroughly.

10. Place curd in sanitized molds and cloth, and press for 15 to 17 hours at 20 to 40 pressure (depending on size of mold).

11, Package in cello-foil impregnated with

' • sorbic acid, or vacuum pack the product.

Weigold found that whole milk with an average fat

percentage of 3,2 produced cheese with smooth texture and

cutting qualities similar to processed cheese. The average

yield of Queso del Pais was 11.5 pounds per 100 pounds of

milk; however, the yield was reduced to eight to ten pounds

when partially skimmed milk was used. In a trial in which

reconstituted povzder was added to whole milk, the yield

increased proportionately with the amount of solids added

(21).

The composition of Queso del Pais made from milk

(with an average fat percentage of 2.2) is 15.0% fat, 51,0%

water, 3.9% salt, 1.8% lactose, and 22,9% protein. As re­

ported by V/eigold (21), Queso del Pais commonly was selling

for 55 to 65 cents a pound in Puerto Rico in 1957,

8

Another type of cheese produced in Puerto Rico from

whole milk is Queso de Prensa. This cheese is a hard

variety manufactured by one of two ways: a) the acetic

acid procedure used for Queso del Pais, or b) ripening the

milk for 6 hours at room temperature, and then coagulating

with rennet. This particular cheese is produced in 2 1/2

to 10 pound sizes and may be consumed fresh, as is Queso

del Pais, or ripened for two to three months (16,23), and

then marketed,

Queso de Hoja and Queso de Puna are cheeses which

are produced on a smaller scale than Queso del Pais and

Queso de Prensa. Both are similar to cottage cheese except

they are molded in conventional hoops (16),

Limited research has been conducted within the

United States on Latin American cheese. Siapantas and

Kosikowski (17) of Cornell University studied the proper­

ties of Queso del Pais as influenced by the addition of

varying amounts of glacial acetic acid as a coagulating

agent (50 to 200 ml per 100 pounds of milk). The glacial

acetic acid was of CP grade and diluted 1:10 with tap water,

Siapantas reported that additions of 110 to 130 ml of acid

per 100 pounds of milk produced cheese of higher quality

than did either lower or higher quantities of acetic acid.

According to Siapantas, levels of acetic acid greater than

140 ml per 100 pounds of milk produced cheese with a sharp

acid flavor, and a brittle texture; levels of acetic acid

below 100 ml per 100 pounds of milk produced a product that

was soft and flat in flavor. No neutralizer was used in

that study; however, Weigold (21) reported that a slightly

acid cheese (acceptable to the Puerto Rican consumer) was

produced when the acidity of the whey was returned to 0,18

to 0,19 per cent acidity through the use of sodium bicar­

bonate as a neutralizer.

Table 2 shows a comparison of the composition of

Queso del Pais with varying amounts of acetic acid. \7hole

milk used in the experiment was standardized to 3.0 per

cent butterfat by weight.

Queso de Cincho is one of the principle cheeses

produced in Venezuela. This cheese is made from fresh

whole milk by the following procedure: a coagulating agent

(cuajo) and salt are added to the milk; the mixture is al­

lowed to set for 24 hours; and the curds are placed in

sacks (resembling flour sacks) and hung until all the vjhey

has drained. The resulting product is soft and is consumed

while fresh (18).

Queso de Mano is another cheese made in substantial

quantities in Venezuela, The manufacturing procedure for

this cheese involves adding a hot coagulating agent (cuajo)

and working the curd by hand until a desirable firmness is

reached, at which time it is placed in wooden molds for 24

• •£f^mm.oji.^

TABLE 2

COMPOSITION OF QUESO DEL PAIS WITH VARYING AMOUNTS OF GLACIAL ACETIC ACID

10

Glacial Acetic Acid Per 100#

of Milk (ml)

50

75

100

110

120

125

130

140

150

160

175

200

Mo i sture (%)

56.7

55,9

52,7

52. 1 1

50.0 '

' 49.8

49.6

60.7

57.2

53.5

53.7

55.3

Protein (%)

25,7

25.5

25.2

24. 6

24,9

25.0

25.9

21.7

23.4

24.9

24.0

25.0

Fat (%)

12.0

14.8

16.2

18.5

19,0

19.0

19,6

13.0

13.5

16.7

17,6

15.0

FDB (%)

27.8

35,6

34.3

38.6

38.0

37,8

37.7

33.1

31,6

35,9

38.9

33.5

•ka»«60.'-v-: -rtH^i

n

hours. It is then wrapped in banana leaves and consumed

with a pancake-like dish called "Cachapa." Other cheeses

such as Queso Llanero, Queso de Cabru, and Cuajada are pro­

duced in Venezuela, but in smaller amounts than Queso de

Cincho and Queso de Mano (18).

In Costa Rica and El Salvador, Queso de Crema is

the principle cheese consume.d. The manufacturing procedure

involves coagulating whole milk with rennet. After the

curd is broken and the whey drained, the cheese is placed

into forms and pressed into approximate one pound sizes.

Salt is applied to the surface of the cheese, and the pro-

duct is allowed to age for a period of two weeks to two

months. According to Sanders, the yield for Queso de Crema

is about 11 pounds per 100 poundr, of milk. In El Salvador,

Queso de Crema is frequently enriched with cream and used

as a substitute for butter. This type of cheese is also

popular in Cuba (l6).

Closer to the United States, in Mexico, various

types of cheese are produced and consumed. As in other

Latin American countries, the general terminology applied

to cheese is "Queso Blanco;" to the Mexican population,

this term only explains that it is a white cheese, and does

not denote any specific type. Therefore, cheese produced in

Mexico is often named for the state in which it is manufac­

tured, such as Queso de Chihuahua, Queso de Oaxaca, Queso

i.vr

12

de Sonora, and Queso de Chiapas. Other names denote the

kind of milk used, such as Queso de Vaca and Queso Cabru

(1, 12).

According to Sanders, Queso Blanco, regardless of

the specific type, is made from whole, partly skimmed, or

skim milk with cream or skim milk powder added (16). Milk

used is of relatively poor quality, especially that used

in making cheese on the farm; this is one of the reasons

why the cheese usually is consumed as a fresh product.

Queso Anejo is an aged cheese made from skim milk.

Packed in jute bags of 11 to 22 pound sizes, this cheese

is cured for six to eight months, Queso Anejo is served

with enchi ladas ,. torti Has , and chile rellenos. Some com-

mercial operations cover the cheese with red chile powder

and market it as Queso Enchilado. Queso de Bola, another

aged product, is made on a small scale from whole milk.

The aging period for this cheese is about three months (16).

The fresh cheeses in Mexico, which are by far the

most common type consumed, include Asadero, Queso Nata,

Panela and Queso de Vaca, Asadero is the type most com­

monly made both commercially and on the farms, Asadero

melts easily upon heating, which accounts for the name

"Asadero" (fit for roasting). This cheese is produced in

eight-ounca to 11 pound sizes and is shaped in the form of

a tortilla (4).

.isma

13

On the farms, Asadero cheese is made with half sweet

and half sour milk. The coagulating agent comes from a t

plant that grows wild in Mexico. The mature berries from

the Silver Leaf Nightshade plant (Solanum elaeagnifolium)

are boiled in water for 10 to 15 minutes and the resulting

mixture added to milk at a temperature of approximately

80° F. After complete coagulation, the curd is cut and

allowed to settle to the bottom of the container. The whey

is then drax rn off and the resulting curd cooked until smooth

and slightly rubbery in texture (8). The cheese is placed

in loaf size containers, allovjed to cool, and then sized

into the shape of a tortilla about one inch thick. Although

the finished product is a cnief component of several Mexican

dishes, considerable amounts of the product are consumed

much like bread. Commercially, rennet is used as the coagu­

lating agent, and a starter is added to give the product a

slightly acid flavor (14).

A report based on actual observations of cheese

preparation in the Mexican home (15) revealed that, in many

cases, tv7o cheese products were manufactured and sold from

each batch of milk processed, Queso de Vaca and Asadero

were obtainable from one lot of milk. In making these

cheeses, milk of varying quality was placed in an enamel

type pan resembling a wash tub. The milk was then heated

to approximately 150^ F and allowed to stand for 30 minutes

14

to meet pasteurization requirements. After the milk was

cooled to about 100* F, rennet was added and the mixture

allowed to set until complete coagulation had taken place.

The- curd was then broken and gently worked by a rolling

motion of the hands until a ball of curd was obtained in

the whey. At this point, the whey, which was white in

color due to the incomplete precipitation of casein, was

drawn off and placed in a separate container. The ball of

curd remaining after removal of the whey portion was

worked or kneaded very carefully by hand until it was firm

in texture. The firm,- partially matted cheese was then

milled in a typical sausage grinder to produce small curd

particles. The resulting curds were placed in round molds i

on a table covered with an oil-treated cloth. The diameter

of these molds was 4-1 inches and produced a finished pro­

duct in the form of a patty, one inch thick. The cheese

remained on the table at room temperature until the next

morning at which time the individual patties vrere wrapped

in wax paper and taken to the market to be sold as Queso

de Vaca. Queso de Vaca is consumed within two days from

the date of manufacture. The flavor of the cheese is bland

to slightly bitter, with firm curd particles which separate

upon chewing. The product in general contains 70.0% mois­

ture, 15.0% protein, and 7.0% fat. (Fig. 1 shows a typical

patty of Queso de Vaca as marketed in Mexico.)

15

The whey portion remaining after the removal of

Queso de Vaca was brought to a boil and allowed to simmer

until the proteins present coagulated. The time involved

before complete coagulation occurred was approximately

three hours. After coagulation, the curd was removed from

the remaining whey and allowed to cool. Upon reaching a

workable temperature, the chfeese was formed into dimensions

similar to tortillas and marketed as Asadero cheese.

Although Queso de Vaca is a very popular cheese in

Mexico, it is not produced commercially in large quantities

but is manufactured arid marketed by families living in rural

areas. Most commercial cheese is manufactured in sizes

ranging from 20 to 50 pounds, and the amount desired by

the consumer is sliced from the larger quantity. Because

of the fine curd particles, Queso de Vaca crumbles easily,

so that slicing is almost impossible. The cheese will hold

its shape, however, in the small one-half to one pound

sizes which are displayed by individual producers.

Another major cheese produced commercially in Mexico

is Queso Nata. (Figure 2 illustrates Queso Nata as sold in

Mexico.) This type cheese is also known as "Panela" in

certain areas of the country (l), Queso Nata is a rather

bland product having only a slightly acid taste. The tex­

ture is smooth, rather moist, and melts easily upon heating.

The product is pressed in 15 to 50 pound molds and has a

x

16

F i g . 1 . - - T y p i c a l ' Jueso de Vaca p a t t y a s na rUo tGc l i n M e x i c o .

Fi", 2 . - - Q u e s o l i a t a a s f o u n d i n r i a r k e t

p l a c G G i n I ' c x i c o ,

17

keeping quality superior to most cheeses produced in Mexico.

Table 3 is a typical make-sheet used by Kraft in the manu-

facturing of Queso Nata (5),

Unlike Queso del Pais, which is made by the direct

acidification method, practically all the cheeses in Mexico

involve the use of bacteria for producing acidity to the

desired degree. Commercially, the bacteria are added in

the form of a starter as is done in the United States.

However, on the farms and in the individual homes, the milk

usually is allowed to set at room teinperature from six to

24 hours to permit development of proper acidity. Some of

the more advanced cheese plants are securing nitrogen frozen

cultures of bacteria from the United States. By using this

type culture, many problems usually associated with starter n

propagation are eliminated.

Except in markets of a few cities bordering Mexico,

Queso Blanco is not available to the people of Spanish

origin in the United States. Kosikovjski (10) reported

that Queso Blanco (probably in the form of Queso del Pais)

is manufactured in the state of New York and made available

to some 800,000 Latin American people living in the New

York City area.

In 1957, Harper and Burgwald (23) developed the

following procedure for making Queso Blanco from recombincd

milk:

TABLE 3

MAKE-SHEET USED BY KRAFT li-i THE MANUFACTURE OF QUESO NATA

18

Time Temp. (° F)

pH Remarks

Pounds Milk Used

% Fat in Milk

Starter Added

Coagulator Added

Curd Cut

Finish Cutting

Draw First Portion of Whey

Finish Drawing First Portion of Whey

Start Agitator

Stop Agitator

Draw Last Portion of Whey

Finish Drawing Last Portion of Whey

Salt

Start Agitator

Stop Agitator

Start Molding

Finish Molding

Press

•

8:35

9:55

10:20

10:35

86

88 6.8

6.7

12,000

3.30

103 lbs

10.38

10:45<.

10:45

10:55

10:58

11:05

11:07

11:13

11:28

11:30

11:35

11:37

88

88

6. 6

6.5

/

6,5

19

1. For each 100 pounds of milk prepa 11 pounds of low heat spray proce fat dry milk and 86 pounds of wat the resulting skim milk and heat for 10 minutes. Draw off three-f skim milk and add three pounds of milk fat to the remaining one-fou milk. Mix thoroughly and homogen resulting 28 pounds of milk at 50 pressure. Mix the t\JO lots of mi cheese vat and cool to 94° F. sition of this milk is 3.0% F, and 13.7% TS,

Th 7.

red, use ss non-er. Mix to 140° F ourths of anhydrous

rth skim ize the 0 pounds Ik in a e compo-75% SNF,

2. Add 0.5 pound of lactic starter per 100 pounds of milk. Allow to set for 30 min­utes.

3. Add 5 ml of saturated CaCl diluted in 40 ml of water to each 100 pounds of milk.

4. Add rennet extract at th"e rate of 9 ml diluted in 100 ml of water per 100 pounds

_ of milk. Allow to set 45 to 60 minutes before cutting,

5. When a firm coagulation has been reached, cut the curd vertically and horizontally with one-fourth or one-half inch cheese knife,

6. Let the curd set undisturbed for 15 min­utes. Then stir gently with a curd rake, and dip the curd into hoops lined with cheese cloth.

Turn the cheese after 30 minutes. After an additional 30 minutes, remove curd from hoops and weigh. Break curd in vat, and salt with sodium chloride at the rate of eight to nine per cent of curd weight,

8. Rehoop and press the cheese using 10 pound weight. Turn the cheese each hour for the first two hours after salting. Then press overnight using 10 to 25 pounds pressure.

7.

20

Although this procedure is evidently feasible in the manu­

facturing of Queso Blanco, it is not mentioned in the

literature as a major commercial procedure used in Mexico,

In certain areas of Texas, a limited amount of

Queso Blanco is available in supermarkets. The trade name

of this Mexican cheese is Queso Mexicano. Queso Mexicano

is similar to the Queso de Vaca produced in Mexico and is

packaged in six-ounce patties 4^ inches in diameter and

one-half inch thick. The fine, minute curd particles

separate easily upon manipulation. The only significant

difference in Queso Mexicano and Queso de Vaca is in the

ingredients, Queso Mexicano is a filled product made from

dry milk solids, vegetable fat, salt, water, stabilizer,

and rennet, whereas Queso de Vaca is m^de from whole milk.

Comparison of Queso Blanco vzi th Cottap^e, Monterey, and Cheddar Cheese

The major differences betv/een Queso Blanco and

cottage cheese are: acidity is developed in cottage cheese

substrate prior to cutting the curd; cottage cheese is not

pressed; skim milk is used in making cottage cheese while

whole milk is the substrate for Queso Blanco; and cottage

cheese curd-whey mixture is heated to 115° F to 120° F to

expel whey, while Queso Blanco is either not heated, or

heated only to approximately 102° F (pressing is used to

remove excess whey).

^SLT.At-. t^-

^ -V ••KW-«HM. . . ;,, '^"V^ym

21

Because of the lack of acid production in the manu^

facturing of Queso Blanco, this product is bland with only

sufficient acid development to give a full, rich flavor.

In the manufacturing of cottage cheese, acid production is

allowed to take place to a higher degree, and coagulation

is caused largely by this production of acid, rather than

rennet action. During the final manufacturing steps of

cottage cheese production, the pH of whey ranges from 4,5

to 4.7 as compared to a pH reading of 6.2 to 6,5 in Queso

Blanco.

Cottage cheese is classified as a soft cheese, *

whereas Queso Blanco more closely fits the classification

of a semi-soft cheese; also cottage cheese is marketed in

a loose curd-like form, whereas Queso Blanco is pressed

into a compact mass. The tvzo products would be more

similar if cottage cheese vrere pressed, as both are white,

and both are consumed as fresh products.

The major difference between Queso Blanco and

Monterey Jack cheese is that acid production by bacteria

during curd formation is allowed in Monterey cheese, and

the curd is washed with water prior to pressing, whereas

this is not true for Queso Blanco. Consequently, Queso

Blanco has a higher percentage of whey solids than does

Monterey Jack. The body and texture characteristics of

Monterey more closely resemble those of cheddar than does

t:^.jxi.-f:^s,--%-rtw.'mnmmmM. I

22

Queso Blanco. Queso Blanco is marketed as a fresh product,

but Monterey Jack is aged for three to six weeks before •

marketing.

The major difference between Queso Blanco and ched­

dar cheese is that cheddar cheese is aged for a minimum

period of three months before marketing. Acid production

is also greater in cheddar cheese manufacture. Queso Blanco

and cheddar cheese differ greatly in appearance, as cheddar

possesses a smoother body and texture, and coloring agents

are used in its manufacture.

CHAPTER III

SCOPE OF INVESTIGATION

The objectives of this study were as follows:

1. To determine if a potential market exists among

the Latin population in V/est Texas for a Mexican-type cheese

similar to *'Queso Blanco" found in Mexico.

2. To make recommendations to the dairy industry

concf-rning the feasibility of producing such a product in

a fluid milk plant.

3. To determine if a filled product in the form of

Mexican cheese can be manufactured which meets consumer

acceptance.

4. To develop a convenient procedure for manufac­

turing Mexican cheese with more desirable flavor charac­

teristics than are now available in similar products.

23

CHAPTER IV

PROCEDURE

The experimental portion of this study was composed*

of two parts: a) an evaluation of the Harper method of

producing Mexican cheese to determine its consumer accept­

ance and adaptability to market milk operations, and b) an

evaluation of a modification of the Harper method in these

respects.

Cheese was produced from homogenized and nonhomog-

enized whole milk, reconstituted milk (composed of 10.0%

skim milk powder, 9.0% cream, and 81.0% water), and recon-

stituted filled milk (composed of 9,0% skim milk powder,

3.0% vegetable fat, and 88,0% water).

The equipment used in manufacturing these cheeses

consisted of a 100 gallon "Nu Vat" cheesemaking vat, several

Damrow five pound galvanized cheese molds, a cylindrical

mold, 4^ inches in diameter and 18 inches in length, and a

Hanna positive pressure cheese press. Samples were stored

in a refrigerator at 54 F and 70 to 75 per cent relative

humidity during the test period.

A total of 40 batches of cheese v/ere produced and

evaluated,. Each batch was organoleptically evaluated by a

group of local Latin American housewives, restaurant owners.

24

25

and/or general businessmen. Also, panelists were chosen

from the college faculty to aid in evaluating the product;

technical terminology was employed to describe the charac­

teristics of all finished products.

Representative samples of each cheese were analyzed

for percentages of moisture, fat, protein, lactose, and

for body, texture and flavor characteristics. The pro­

cedures used in analyzing each batch of cheese for moisture,

fat, protein, and lactose are outlined below.

Procedures for Analysis

Fat. The procedure for determining fat was the

standard Babcock test of cheese outlined below by Goss (7):

1. Balance tv/o 50% Babcock cream test bottles on a cream test scale. Then place a 9 gram weight on the right pan.

2. Balance scales by dropping pieces of cheese into the test bottle placed on the left side of scale,

3. Remove 9 gram vreight and place cheese into test bottle on right side until the scales are balanced.

4. Add 12 ml of 180° F water to each test bottle and place in water bath at 180° F or above for 5 minutes,

5. Add 17.5 ml of sulfuric acid (spe­cific gravity 1.82 to 1.83) to each test bot­tle. First add only 1 to 2 ml of acid at a time, but later 3 to 4 ml additions until the entire 17.5 ml of acid is present in each test bottle. Mix well after each addition.

26

6, After all lumps are dissolved, cen­trifuge for 5, 2, and 1 minute periods, add­ing 140° F water after the first and second whirlings,

7. Place the test bottles in a 135° F to 140° F water bath for 3 minutes; add glymol and read at once.

Protein, The standard A,O.A.C, test for protein

was used to determine the amount of protein present in each

batch of cheese. Reagents needed for a standard Kjeldahl

(9) determination are as follows:

1, Sulfuric acid--concentrated 93% to 96%.

2. Digestion mixture--contains 3,2 parts finely ground copper sulfate and 96.8 parts anhydrous sodium sulfate by weight.

3. ' Sodium hydroxide--dissolve 500 grams of sodium hydroxide in 1 liter of water in a heat resistant container. Allow to cool, and transfer to storage bottle,

4, Boric acid solution--prepare a 4% solution by dissolving 40 grams boric acid in 1 liter of warm (176° F) distilled water. After cooking, add mixed indicator,

5, Mixed indicator--make up separately a ,1% bromcresol green solution (.1 gram per 100 ml water) and a ,1% solution of methyl red using 95% ethyl alcohol as the solvent. Add to cool boric acid solution at the rate of 2,5 ml bromcresol green solution and 1,5 ml methyl red solution per liter. For 6 liters of boric acid, use 15 ml bromcresol green and 10 ml methyl red,

6. Hydrochloric acid--use 8.2 ml of con­centrated hydrochloric acid per liter of dis­tilled water. This gives approximately a .1 N solution. Standardize with standard sodium hydroxide.

belov7:

27

The procedure for the standard Kjeldanl is outlined

1, Weigh 1 to 2 grams of cheese and place in Kjeldahl flask,

2, Add one teaspoon of digestion mi::.

3, Add 25 ml concentrated sulfuric acid. Run acid dovjn the sides of the flask to remove any particles of cheese v/hich may be sticking to the neck,

4, Place on heating clement and digest for 15 minutes after the contents have turned green.

5, Vihen the mixture is almost oxidized, turn the flasl: 1/2 turn to bring side and top residue into solution,

6, Cool, and add 200 ml tap water. The determination may be stopped at this point if the flask is plugged,

7, Four 50 ml of 4% boric acid solution into a 500 ml Erlenmeyer flask and place under the distillation condenser tubes. Do sure, that the distillation tube is belov the sur­face of boric acid in the flask.

When the Kjoldahl flask and contents are completely cool, add 70 ml of concentrated sodium hydroxide, letting it run down the side of the flask. If no blue line is present be­tween the layers, add a few more ml of sodium hydroxide.

9. Place Kjeldahl flask in distillation apparatus without shaking or disturbing the layers. Turn on water and heating elements,

10, Mix contents by shaking.

11. Distill for 20 minutes after the in­dicator in the boric acid solution has turned green, or until 150 ml of liquid has been collected in the boric acid solution.

2V.

12. Titrate with standard hydrochloric acid to a delicate end-point betTjeen sreen and red. The end-point is reached when solution is clear in appearance,

13. Percentage of crude protein equals (ml HCl-ml blank) (>> of acid) (,014) (6.25) (lOO)

Sample Weight

Moisture. The standard method (7) for moisture

percentage determination is outlined below:

1, In pre-dried and'cool'ed moisture ' dishes about 50 mm in diameter and 22 mm deep, weigh 5 grams of sample into each dish and cover immediately. Test should be made in duplicate for the greatest accuracy,

2, Place samples in a 212° F oven for 24 hours. To decrease drying time, a small amount of pre-dried sand may be added to the samp 1e,

3, Re:nove and place in a desiccator for 1 hour or until the samples reach room temperature.

4, Remove from desiccator and v/eigh.

5, Percentage moisture equals Weif!;ht after drying ^ J QQ

Weight of original sample

Lactose. A combination of the Takahashi test (19)

and a test developed by Eastham (3) was used to determine

the percentage lactose present. Reagents needed for this

determination are as follows:

1. Standard sugar solution--one gram of crystalline benzoic acid and 2.045 grams of crystalline dextrose dissolved in water made up to 1 liter.

29

2. Copper solution--66 grams of crys­talline copper sulfate dissolved in water and made up to one liter with water.

3. Alkaline solution--sodium hydroxide (110 grams) and rochelle salt (345 grams) dissolved in water and made up to 1 liter.

4. Copper and alkaline solution--equal volumes of solutions No, 2 and 3 (above) are mixed thoroughly,

5. 10% lead acetate solution.

6. 10% potassium oxalate solution,

7. Methylene blue indicator--^ gram of methylene blue dissolved in 100 ml of . water.

The procedure for the determination of percentage

lactose is outline below:

1. Weigh 15 grams of cheese sample into a 250 ml volumetric flask.

2. Treat with 25 ml of 10% lead acetate and complete the volume with dis­tilled water.

3. Shake well and obtain 100 ml of filtrate by the use of No, 40 Whatman fil­ter paper.

4. Treat the above filtrate with 10 ml 10% potassium oxalate and dilute to 200 ml with distilled water,

5. Obtain 20 ml of the resulting solution and place into a 250 ml Erlenmeyer flask.

6. Add 10 ml of copper reagent and heat over a flame.

7. After one minute of boiling, add 4 drops of indicator and begin titrating with the standard sugar solution.

M — . g y y II •••hVkj^jg'Ttiflii^")

30

8, The titration should be completed at the end of two additional minutes, (Care should be taken not to lose the boil during titration,)

9, The end-point is reached when the blue color just begins to change to purple.

Yield, The yield was calculated for each batch by

the following formula:

i^ cheese obtained X 100 Percentage yield « # milk

Fat; Dry Basis, The fat-in-dry matter was calcu­

lated by use of the following formula:

Percentage FDB « % fat in cheese X 100 100 - % moisture in cheese

Manufacturing Procedures

Whole milk of good quality was obtained for this

study from the Texas Technological College dairy farm. All

whole milk was pasteurized at 165° F for 15 seconds, and

portions were homogenized at 1700 PSIG, The skim-cream

mixtures aR4 filled millcs were pasteurized by heating the

milk to 145° F for 30 minutes, after which they were homog­

enized at 1000 PSIG, The fat contents of the whole and re­

constituted milks were standardized at 3.7 per cent.) Both

coconut oil (3 per cent of total weight of cheese milk) and

a source of commercial soybean oil were used to provide fat

for the filled milk preparations. Total solids in the re­

constituted milk and filled milks were 11,5% and 11.95%,

respectively.

31

Commercial strains of both Streptococcus lactis and

Lactobacillus bulgarius were used in making experimental

batches of cheese, and regardless of which culture type was

used, 0.5 pounds of starter was added per 100 pounds of milk

as described in Harper's procedure](23). The starters were

kept active by transferring them every other day and dis-*

carding the cultures at the end of 10 transfers. At various

stages of the manufacturing procedure, pH readings were made

on the milks; namely before setting the milk, after cutting

the curd, after cooking-the mixture, and after draining the

whey.

Sodium chloride was added to the finished curd in

amounts ranging from 1% to 9% by weight. In several trials,

1% sodium citrate (W:W) was added simultaneously with the

sodium chloride. The purpose of sodium citrate addition was

to check its effect on body and texture, and melting quali­

ties of the final product.

Detailed Procedure for Making Mexican Cheese

The two procedures used in manufacturing Mexican

cheese in this study were Harper's procedure and a modifica'

tion of Harper's method.

Harper's Method. This method was adapted to condi­

tions in Mexico in that a) reconstituted milk was prepared

from skim milk powder and butteroil, and b) the procedure

32

was adapted to the processing equipment predominant in that

country. The procedure outlined below is essentially that

recommended by Harper with the above two exceptions,

1, Place milk in cheese vat and heat to 94° F, (Check the pH at this time,)

2, Add 0,5 pounds starter per 100 pounds of milk and allow to set for 30 min­utes. Take a pH reading after adding starter and again after the 30 minute waiting period.

3, Add rennet extract (diluted 40 times with water) at a rate of 8 ml per 100 pounds of milk. (When skim-cream mixtures or filled milks were used, a saturated solu­tion of calcium chloride was added at a rate of 5 ml diluted in 40 ml of water per 100 pounds of milk, in addition to the rennet preparation,)

4, Allow milk to set undisturbed for 30 to 45 minutes or until firm coagulation has taken place.

5, Cut curd vertically, lengthwise and crosswise with ^ inch cheese knives. Determine pH of whey,

6, Allow curd to set undisturbed for 15 minutes. After 15 minutes, gently dip the curd into hoops lined with cheese cloth.

7, Turn cheese after 30 minutes. At the end of an additional 30 minutes, remove cheese from hoops and weigh.

8, Break curd in vat and salt at an average rate of 2.5% of curd weight. (Harp­er's procedure called for 8% to 9% salt by weight of curd; however, salt content was varied from 1% to 9% in this study.)

9, Rehoop and press overnight at 10 PSIG. (Turn each hour for the first two hours,)

33

10. Place cheese in cooler at 54° F and 70 to 75% relative humidity for 48 to 72 hours.

11. Heat paraffin to 240° to 250° F and dip cheese for 3 to 6 seconds. After cool enough to handle, return to cooler, (This paraffining procedure was not in­cluded in Harper's recommendations, 'but was added here to provide a convenient package for use in presenting the product to panelists,)

Experimental Manufacturing Procedure. The modifi­

cation of the Harper Method is outlined below.

1, Place milk in cheese vat and heat to 94° F (check the pH at this time),

2, Add 0.5 pounds starter per 100 pounds of milk and allow to set for 30 minutes. Take a pH reading after adding starter and again after the 30 minute waiting period. (See Figure 3,)

3, Add 10 ml of rennet diluted 40 times in tap water per 100 pounds of milk. (Figure 4)

4, Allow milk to set undisturbed for 30 to 45 minutes or until firm coagu­lation has taken place,

5, Cut curd vertically, lengthwise, and crosswise with ^ inch cheese knives. Determine pH of whey, (Figure 5)

6, Allow curd to remain undisturbed for 15 minutes. At the end of 15 minutes, begin the cooking period. Increase tem­perature at a rate of 1° F each 5 minutes until the curd reaches 100° F, Then in­crease heat slowly until curd reaches 102° F,- The cooking period should be 30 to 35 minutes.

3 :

3

7. After coohing, continue agitr.tion for 30 to 45 minutes. VHien curd is firm to the touch, drain whey, (Figure 6)

8. Allow curd to set undisturbed in the vat for an additional 30 r.iinutes, (There should be continuous agitation in a commercial operation.)

9. V/eigh the curd and add sodium chloride. (Figure 7)

10. Hoop and press at 18 to 20 PSIG for 15 to 17 hours. (Figure 8)

11. Place in 54° F cooler at 70 to 75% relative humidity for 48 to 72 hours.

12. Paraffin and return to cooler. (Figure 9)

Evaluation by Panelists

Each of the cheeses was submitted to panelists

located at five Latin American restaurants in the city

of Lubbock, Texas, The products were evaluated organo-

leptically and checked for melting qualities on various

Mexican-type foods. Employees and friends of the

restaurant ovzners comprised the consumer panels (approx­

imately 25 panelists were involved). All panelists were

familiar with cheeses produced in Mexico and in other

Latin American countries. Opinions of these panelists

concerning quality, desirability, and market potential

of the products were recorded and later analyzed to

determine the feasibility of recommending Mexican cheese

as a suitable commodity for production and jsarketing by

retail milk plants.

38

F i g . 9 - - E q u i p i n e n t u s e d i n p a r a f f i n i n g Mexican c h e e s e

CHAPXER V

RESULTS AMD DISCUSSION

The major areas of concern regarding the manufac­

ture of Mexican cheese in this experiment were a) the most

suitable type of equipment to use, b) cooking temperatures

which should be employed, c) proper procedures for adding

rennet, d) pressing conditions, e) types of milk best

suited for cheese manufacture, f) salting procedures to

follow, and g) type of organism to use. Also, comparisons

were made of cheese made by Harper's method (23) versus

the experimental method developed in this study.

Type of Equipinent

One of the major objectives of this experiment vras

to develop a procedure whereby existing cottage cheese

equipment in market milk plants could be used with slight

modification to produce Mexican-type cheese. Preliminary

experiments in this area sho\7ed that such equipment is

satisfactory for making the product provided market riilk

plants V70uld add to their existing equipment a cheese

press of some type, and a supply of suitable molds for

pressing cheese curd into desired shapes. Because of the

nature of the product, it would be necessary for plants

39

40

to either develop some type of automatic packing equipment

to handle the unique product, or to make arrangements to

package it by hand.

Regular cottage cheese equipment was found to be

satisfactory for manufacturing the curd for Mexican cheese

since this curd is cut and cooked in almost the same manner

as that used in the manufacture of regular cottage cheese.

Since the product should have a keeping quality of two

weeks or more under refrigerated conditions, and since

the cheese was to be marketed in semi-solid rather than

curd form, several types of molds were evaluated.

Two types of cheese molds were used in this study.

One was designed to produce a cheese, spherical in shape,

weighing approximately five pounds (see Figure 10), and

the other was a cylindrically shaped mold with inside di­

mensions of 4^ inches by 18 inches (Figure ll). The spher­

ical mold, in commercial production, is used routinely by

manufacturers of American cheddar cheese. The cylindrical

mold was an experimental one designed especially for this

study. As can be seen in Figure 12, it consisted of rolled,

galvanized metal with three hinges. Additional ring clamps

were placed at each end of the mold to render strength to

the apparatus during pressing. Figure 13 indicates that

the mold is open-ended with spacers provided at each end

which fit freely into the mold. The reasons for these

41

Fig. 10"-Spherica1 molds used to form Mexican cheese weighing approximately five pounds.

Fig. ll"-Bandaged cylindrical mold v/ith dimensions of 4-2 inches by 18 inches.

42

Fig. 12"-Exporimenta1 cylindrical mold made from rolled, galvanized metal.

Fig. 13--Pressing of Mexican cheese in experimental mold.

43

spacers were to make it possible to press more tlu.ii cue

mold at a time and to insure constant pressure throughout

the cheese during the pressing period.

The reason for using the cylindrical mold to pro­

duce Mexican cheese was to provide a test cheese shaped

so that "cheese patties" similar to the ones marketed in

Mexico could be conveniently manufactured. Figure 14 shov7S

that when the cheeses were removed from these molds, patties

of varying thickness from one-half to an inch and a half

could be sliced and packaged. Surveys of the Mexican cheese

industry indicated that patties of this type are popular

with the consumer in Mexico,

Experimentally, cheese pressed in these molds was

submitted to f*ive to eight pounds pressure for 17 hours,

removed from the mold, sliced into patties of approximately

one inch thickness, and wrapped in cellophane. Simultane­

ously, identical cheeses were pressed for 17 hours in the

spherical molds, as shown in Figure 15. These cheeses were

paraffined by dipping in liquid paraffin vrhich solidified

upon cooling to room temperature. (See Figure 16.) Some

problems were encountered with the latter procedure in ob­

taining a satisfactory paraffined cheese. Because of the

high moisture present in the cheese, the paraffin tended

to "peel" from the cheese. However, the problen was solved

by allowing the cheese to dry while in refrigerated storage

44

Fig, 14--Sliced Mexican cheese patty ftcr pressing in experimental mold.

g spherical molds.

Fir. iS-^Pressing of Mexican cheese in

45

• • •

Fig. 16--Paraffining of spherical Mexican cheese

46

for three to four days before paraffining. During this

time, the cheese was turned daily to increase the drying

of all surfaces.

When the cheeses were submitted to panelists, both

types were acceptable, but they suggested that the five

pound sizes shown in Figure 16 would probably be more

popular with institutions such as restaurants, whereas

the patty size would be more popular for retail sales.

The major results of this phase of the experiment could

be summarized by saying that cottage cheese equipment may

be used for the manufacture of Mexican cheese curd; cylin­

drical molds are satisfactory for producing cheese patties;

and five pound sizes of cheese in spherical molds should

not be paraffined unless allowed to dry for a period of

three to four days. Five pound sizes could be wrapped in

cellophane immediately after processing and marketed suc­

cessfully through a commercial outlet.

Cooking Temperature

Ordinarily, Mexicans do not include a cooking pro­

cedure in the manufacture of Mexican cheese. Harper recom­

mended the following abbreviated procedure which excludes

a cooking period (23):

1, After cutting, allow curds to set undisturbed for 15 minutes, and place in molds.

47

2, At the end of 30 minutes, re­move cheese, invert, and return to molds for an additional 30 minutes,

3, Remove from molds, salt, replace in dressed molds, and press, using 10 pound weights,

4, Turn molds every hour for two hours, and press overnight at 10 to 25 pounds pressure.

Apparently, Harper recommended several handlings of

the product during pressing in an attempt to remove as much

moisture as possible without producing a low-moisture

cheese. He also wanted to develop a cheese which would

have a crumbly body and texture, rather than a firm texture

similar to American cheddar cheese.

To eliminate at least a portion of the handling of

cheese curd during pressing, an experimental cooking pro­

cedure was developed which would cause the curd to drain

its moisture more easily during a single pressing. Accord­

ingly, several batches of cheese were made whereby the curd

(after cutting) was allowed to remain undisturbed for 15

minutes to allow the curd to "heal"; heat was then applied

slowly to effect an increase of approximately 1° F in tem­

perature during the first 10 minutes of cooking. At that

point, the rate of heating was increased gradually until a

final temperature of 102° F was reached during an additional

25 to 30 minutes. According to Davis (2), care must be

exercised during the cooking period not to raise the

48

temperature too quickly or the outside portion of the curd

will become tough, and trap moisture inside the curd par­

ticles. If this condition were allowed to develop, the

final product would possibly exhibit a weak body and, upon

storage, would become leaky, a condition in which whey­

like fluid exudes from the cheese. After the cheese

reached a temperature of 102° F, agitation was continued

for an additional 30 minutes to allow further moisture

drainage from the curd particles and for the curd to firm

sufficiently to make handling easier during subsequent

manufacturing steps.

The procedure for pressing the cheese after cook­

ing is outlined as follows:

1, After cooking, drain whey and

allow curd to set undisturbed 30 minutes

or more,

2, Salt and place in a dressed

cheese mold,

3, Apply five pounds of pressure

per square inch for 30 minutes.

4, Dress hoops and increase pres­

sure to 10 pounds, pressing for 45 minutes,

5, Increase pressure slowly to 18

to 20 pounds per square inch and leave

for 17 hours.

49

6, Release pressure and remove cheese

from hoops.

The results of this portion of the study could be

summarized as follows;

1, A final cooking temperature of 102° F is not

as critical as could be encountered in the manufacture of

cottage and cheddar-type cheeses because acid production

is not of prime importance during the subsequent ripening

period,

2, The curds prepared by this method were much

easier to handle in subsequent operations than similar

cheeses produced by Harper's method,

3, The finished product, after pressing, was

firmer and somewhat drier in texture than cheese manufac­

tured by Harper's method,

4, Panelists found the product desirable, espe­

cially its mealy texture (crumbly),

5, The finished product had a better eating

quality than similar cheeses made by the Harper procedure.

Cheese prepared by Harper's method was difficult to

press in that the curd was soft, and had such a high mois­

ture content that extreme mechanical losses were incurred

when attempting to remove excess moisture at the press.

The resulting cheese a) did not possess a continuous net­

work of curd, b) had a large proportion of mechanical

50

openings, and c) contained excessive amounts of free whey.

During storage the cheese became leaky, and the keeping

quality was reduced considerably. Figures 17 and 18 il­

lustrate the cheese prepared by this method. On the other

hand, cheese produced by the cooking procedure tended to

have satisfactory pressing qualities in that a) less curd

was lost, b) higher pressures could be applied to increase

efficient whey removal, and c) the pressed product was firm

and lacked excessive amounts of moisture. Figures 19 and

20 illustrate the cheese produced by this cooking procedure.

Addition of Rennet

Ordinarily, in the making of Mexican-type cheese,

milk is introduced to the vat and a starter culture of

bacteria is added, followed by a 30 minute waiting period

during which the milk sets quiescently in order for two

generations of bacteria to develop (6), While experi­

menting with procedural methods, the pH readings did not

change more than 0.5 units from the time starter was added

until rennet was introduced 30 minutes later. In view of

this observation and since acidity development is not of

critical importance, sample batches of cheese were prepared

by adding the rennet enzyme simultaneously with, or as soon

as possible after the addition of starter. Rennet was

added in the same proportions as is recommended for

51

Fig, 17--Fresh Mexican cheese manufactured by Harper's method. Large mechanical openings indicate V7hcy retention.

Fig, 18--Mexican cheese manufactured by Harper's method showing reduced volur.ie follo^:ing leakage of free whey after storage.

52

Fig, 19°"Fresh Mexican cheese manu­factured by experimental method. Note fewer mechanical openings.

Fig. 20--Experimental Mexican cheese after storage. No decrease in volume has occurred,

53

conventional methods (10 ml diluted 40 times in water, per

100 pounds of milk).

The results of this experiment showed that adding

rennet simultaneously with the starter did not affect the

coagulation time of the milk, and panel members could not

detect any noticeable change in flavor of cheeses prepared

by this method as compared to those made by the conven­

tional procedure.

Variations in Type of Milk Used

Several types and sources of milk were evaluated

in the study to determine if significant differences

occurred in cheeses prepared from these sources. Types

of milk used included homogenized whole milk, nonhomog-

enized whole milk, whole milk made by reconstituting

skimmilk powder and cream, and filled milk containing

skimmilk powder and vegetable fat in addition to water.

The milk preparations made from cream and skimmilk powder

plus water were pasteurized, homogenized at 500 pounds per

square inch pressure, and cooled to the desired tempera­

ture of 86° F, before beginning the manufacturing process.

Filled milk preparations were made in a similar manner

except that 5 ml of saturated calcium chloride solution

diluted 40 times in cool tap water per 100 pounds of milk

were added at the beginning of the procedure. Sources of

54

vegetable fat included those from commercial preparations

of soybean oil and coconut oil. Samples of finished

cheeses from these sources of milk were submitted to

panelists for their evaluation. Results of this phase

of the experiment are itemized in the following paragraphs,

1, Cheeses prepared from homogenized milk pos­

sessed better slicing qualities than did cheeses from any

of the other types of milk, i,e, a firm, non-gummy, clean

slice could be obtained easily upon cutting the cheese.

This slicing property was found to be relatively unimpor­

tant according to the Mexican panelists, because they sel­

dom eat sliced cheese as such. They prefer one that is

more crumbly and more easily broken when used in prepared

dishes.

2, Cheeses made from homogenized milk tended to

develop a more gummy, sticky texture than did cheeses from

other sources, especially after the cheese had been stored

for as long as two weeks. This was attributed to the curd

tension being lowered in milk when it is homogenized, re­

sulting in a cheese that tends to lose its firm body with

age (2).

3, Homogenized milk produced higher curd losses

than any of the other milks. This was attributed to the

fact that the milk had been submitted to pressure of

approximately 2,000 pounds per square inch during the

55

homogenization procedure. Such a process tends also to

increase curd losses when manufacturing cottage cheese

and American-type cheeses (2).

4, Whey expulsion was easier to effect during the

cooking period with non-homogenized milk than with any of

the other milks tested. Individual curds showed a "bright­

ness" and individuality that was not present in curds from

other milks. A certain sheen, or brightness, is recognized

by experienced cheese makers as being an Indication that

the final product will press successfully. Furthermore,

problems encountered in the pressing phase of the pro­

cedure (those associated with curd loss during the early

stages of pressing) were considerably less than those

associated with cheeses from other milks.

5, In comparing cheeses made from homogenized

milk, non-homogenized milk, and reconstituted milk, panel­

ists agreed that those products made from whole, non-

homogenized milk were generally superior to the other

products. The cheese made from whole milk had better

melting properties when used in dishes requiring cheese

on the surface of the dish prior to cooking. Panel mem­

bers preferred the ease with which the whole milk cheese

crumbled when this property was desired in dish preparation,

6, Cheeses made from filled milk, in which soy­

bean oil was the chief source of fat, exhibited a distinct

56

soybean taste which was considered undesirable by the panel

members. Cheese made with coconut oil, however, did not

exhibit such a flavor and was satisfactory in this respect.

In fact, the panelists considered the cheese to have an

appearance, flavor, and texture comparable to that made

from regular milk. However, melting qualities of the cheese

were relatively poor when used in the preparation of Mexican-

type dishes. Instead of melting upon cooking, the curd

particles turned hard and brown and remained in "chunks,"

rather than becoming viscous. The cheese did not melt when

wrapped in a tortilla or cooked as an enchilada dish but

became dry instead. The poor melting property was of major

concern to restaurant owners.

In summarizing, the conclusion is that Mexican cheese

made from nonhomogenized whole milk was superior to those

cheeses made from milk from other sources. This cheese had

better melting quality, was easier to manufacture, and in

general more nearly met the desires of Latin American panel­

ists. Not only is it unnecessary to homogenize milk prior

to manufacturing Mexican cheese, but such a step is undesir­

able, because of the fact that the product is more difficult

to manufacture, and because the cheese becomes gummy and

sticky after a week or more of storage at refrigerated

temperatures. A satisfactory Mexican cheese can be made

with filled milk provided coconut oil and not soy oil is

57

used as the major source of fat, insofar as flavor, body,

texture, and general appearance of the cheese is concerned.

However, one may expect consumer dissatisfaction with such

a product if some method is not devised to modify the

cheese so as to improve the melting qualities during food

preparation.

Variations in Salting Procedures

Harper and Burgwald (23) suggest the use of 8% to

9% sodium chloride by weight of curd in the finished pro­

duct. However, results obtained from comments of panelists

who tasted cheese with this amount of salt indicated that

Latin Americans in this country would probably express an

extreme dislike for products with such a high percentage

of salt. Several samples of cheese were made containing

percentages of salt varying from 1% to 9% and submitted

to the panelists for evaluation. Repeated experiments in

this area verified the fact that the optimum amount of salt

preferred by panelists in Mexican cheese was 2,5% by weight

of curd.

In another series of studies associated with salt

concentration, sodium citrate was added along with sodium

chloride for the purpose of hydrating the casein to the

point that texture would be smoother and melting quality of

the cheese improved. In these experiments, 1% sodium

58

citrate by weight of cheese was added simultaneously with

the sodium chloride (after cooking and draining of the curd,

and before pressing). Evaluations of the finished product

containing sodium citrate indicated that the melting quality

of the cheese was improved as compared to those cheeses not

containing sodium citrat'e. However, problems were experi­

enced during manufacturing, in that the cheese was more

difficult to press into a satisfactory product unless the

curd was cooked to temperatures in the range of 102-110° F

and held for a longer period of time (30 minutes or longer);

this procedure allowed for a firmer, drier product prior to

salting. When more than 1% sodium citrate was used, panel­

ists criticized the cheese for being bitter and therefore,

highly undesirable; furthermore, when citrate was used as

an ingredient, the resulting cheese did not have crumbly

characteristics which panelists insisted Mexican cheese

should have in order to be satisfactory. They expressed

an opinion that such a cheese, whether it be made from

whole milk or filled milk, would be satisfactory to Latin

Americans as a "sandwich" cheese.

TY£ es of Organisms Used in Cultures

Evaluations were made of several batches of cheese

manufactured with two types of microorganisms as cultures;

one group of cheeses contained Streptococcus lactis culture

59 .

in amounts varying from 0.5% to 1%, on a total milk basis,

and the other contained like amounts of Lactobaci11 is

bulgaricus culture. When these cheeses were submitted to

panel members, they were quick to express a dislike for the

cheese containing Lactobaci11 is bulgaricus. They considered

it bitter, with an excessively acid taste. The panelists

pointed out that Mexican cheese should be extremely bland,

with only a slightly acid taste. They strongly preferred

cheese containing a small amount of Streptococcus lactis

culture. Apparently, however, they were not so much in­

terested in the acid flavor that lactic starter contri­

buted, as they were with the "full" flavor associated with

such cheese.

General Composition of Cheeses Prepared

Representative samples of the various cheese pro­

duced were analyzed for percentages of protein, moisture,

fat, fat-in-dry matter, lactose, and yield.

Table 4 reveals six subdivisions; namely, composi­

tions of replicates of cheese manufactured from a) homoge­

nized milk by Harper's procedure, b) homogenized milk by

the experimental procedure, c) nonhomogenized milk by the

experimental procedure, d) reconstituted skim milk and 40%

cream by Harper's procedure, and e) reconstituted skim and

vegetable fat mixtures by the experimental procedure.

I 60

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62

Section 6 of the table shows average compositions of cheeses

made from the different milks and manufacturing procedures,

A comparison of Sections 1 and 2 of this table

shows the major differences between cheese made from homog­

enized milk by Harper's method and cheese made from homog­

enized milk by the experimental method. The percentages of

protein and fat in cheeses made by Harper's method were

lower than those percentages in cheese made by the experi­

mental method. The percentage moisture in cheese made by

the Harper method was higher; subsequent organoleptic evalu­

ations showed cheeses made by the experimental method were

firmer, more crumbly in texture, and had better keeping

qualities because more moisture was pressed from the cheeses.

Although a slightly lower percentage yield was obtained,

this was compensated for by the increased amount of milk

solids in the cheese.

According to Sections 2 and 3 of Table 4, cheeses

made from nonhomogenized milk were higher in protein and

moisture, but lower in fat. The yields of cheeses made

with the two milks were practically the same, indicating

that during the manufacturing of cheese from nonhomogenized

milk, more fat is lost in the whey than when using homog­

enized milk. Simultaneously, however, a greater loss of

protein occurred during the manufacture of cheese from

homogenized milk. Therefore, in order to obtain cheeses

63

with similar firmness, more moisture must be removed from

curd made from homogenized milk during the cooking pro­

cedure than is necessary for curd made from nonhomogenized

milk.

In Sections 4 and 5, comparisons were not made

between cheeses made both by Harper's method and the ex­

perimental method due to observations made in early ex­

perimentations. In those trials, in which Harper's method

was employed, homogenized milk was compared to reconsti­

tuted milk with regard to consumer preference. Early

experimentation indicated that Harper's method produced

cheese which was too soft, would not crumble easily, and

had poor keeping quality. At that point. Harper's method

was discontinued and all subsequent batches of cheese

were made by the experimental method.

The fourth section of Table 4 shows that yields

were higher in reconstituted milk products than in all

other cheeses. The reason for this was that the recon-

stituted milk originally was higher in percentage protein

than that of the other sources. In fact, where the other

milks contained approximately 8.7% MSNF and 3,5% fat, the

reconstituted milks were prepared by adding enough milk

powder and cream to produce a milk containing approxi­

mately 10,5% MSNF and 3,6% fat. Consequently, when the

finished cheese was weighed, a higher yield per 100 pounds

64

of original milk was expected. One should not interpret

the data to mean that higher yields may be obtained from

reconstituted milk than from unhomogenized or homogenized

milk.

Section 4 of Table 4 indicates a higher percentage

of moisture in the finished cheese from reconstituted milk

than in cheeses made by the experimental method. The

Harper method consistently gave a wetter, more leaky

cheese.

Section 5 of Table 4 shows the composition of

batches of cheese made from filled milk. The percentages

of protein, fat, lactose, and moisture compared favorably

with cheeses made from the other types of milk, although

even greater proportions of protein solids were retrieved.

There was no explainable reason for this phenomenon, and

insufficient trials were run to provide a basis for cer-

tainity in this regard. This section of the table also

demonstrates that lower yields were obtained from filled

milk than from any of the other cheeses. This is ex­

plained by the fact that the original filled milk con­

tained 8,5% MSNF and 3.0% fat as compared to 8,7% SNF

and 3.5% fat in whole milk.

Section 6 of Table 4 is a brief summary of the

other five sections and is inserted for convenience in

summarizing the information already discussed.

65

Composition and Evaluation of a Mexican Cheese Marketed in Local Supermarkets

A survey of supermarkets in the Lubbock area re­

vealed that a Latin American type cheese is available to

the consumer. This product is a filled cheese made from

powdered milk, vegetable fat, salt, water, stabilizer, and

rennet. The approximate composition of this cheese is

19,6% protein, 52.4% moisture, 19.0% fat, 41.0% fat-in-dry

matter, and 5,2% lactose. The product is manufactured in

San Antonio, Texas, and distributed statewide as a frozen

food. After it is placed on the grocers' shelf, the tem­

perature of the cheese reaches equilibrium with the cold

storage compartment. The product is marketed in patty

form, approximately 4% inches in diameter and one inch

thick, with a net weight of eight ounces.

Samples of this cheese were submitted to the con­

sumer panel which reacted favorably to the product. How­

ever, they preferred the cheese either similar to the

types manufactured in Mexico or the ones manufactured in

this study. All members of the panel had prior knowledge

of the commercial product and admitted having consumed it

several times. They indicated that the product lacked the

full, rich flavor associated with the experimental batches

of cheese, but favored the body and texture characteris­

tics, namely the crumbliness. Although the manufacturing

66

procedure for this product is unknown, the harder, more

crumbly curd formation is assumed to be obtained by the

use of a filled milk without the use of a starter, and

possibly by using a higher cooking temperature than used

in this study. Perhaps more research is needed in this

area to develop a procedure for manufacturing Mexican cheese

without the use of cultures. If this is done, however, one

can expect to sacrifice the full, rich flavor so desirable

to the panelists.

General Observations Concerning; the Experiment

The results of this experiment would seem to indi­

cate that, although a Mexican cheese manufactured from

whole, nonhomogenized milk was preferred by panelists, and

although this type product can be conveniently manufactured

in existing cottage cheese equipment, a filled milk cheese

might be perfected which would meet most of the demands of

the Latin American population in this area with respect to

body and texture characteristics. If procedures were used

to give a desirable flavor, however, the body of the

finished product possibly would not be as satisfactory as

that associated with a filled cheese without any bacterial

culture in the recipe.

The question as to what measures should be under­

taken to develop modified procedures to give maximum flavor

67

desirability while producing a body and texture that is

rough and crumbly, was not answered. One possibility is

that milk curd could be manufactured with a combination of

rennet and commercial lactic acid. This type of procedure

is being used at the present time on a limited basis in

pilot plant studies over the nation for the manufacture of

cottage and cheddar cheeses, and would possibly be a good

method for the manufacture of Mexican cheese. This seems

even more plausible when one considers the fact that Latin

Americans apparently prefer an extremely bland cheese,

along with a tough, crumbly texture. This is one of the

major difficulties being encountered with the procedure

in the manufacture of cottage cheese at the present time.

Future studies in this area should consider the feasibility

of manufacturing Mexican type cheese without the aid of

lactic starter organisms.

CHAPTER VI

SUMMARY

The primary objectives of this study were to a) de­

termine reactions of Latin American people living in the

Lubbock, Texas, area to a particular type of Mexican cheese;

b) to develop a convenient procedure for manufacturing the

product using cottage cheese equipment; c) to make recom­

mendations to the dairy industry concerning the feasibility

of marketing such a product; and d) to determine if recon­

stituted and filled milks could be used to make a satis­

factory product.

Several batches of cheese were made by a procedure

recommended by Harper (23), with the exception that whole

milk was used as the substrate rather than reconstituted

milk made from milk powder, butteroil and water. The

keeping qualities of this cheese were poor, because of the

relatively high moisture content of the product. Accord­

ingly, a modified procedure was developed, in which the

curd was first formed with Streptococcus lactis culture

and rennet enzyme at 94** F, followed by a conventional

cooking procedure similar to that found in most cheddar

cheese manufacturing methods. The cooking period was in­

cluded to expel a greater amount of whey from the curd

before pressing,

68

69

Cheeses were made from homogenized whole milk, non-

homogenized whole milk, reconstituted milk (containing skim

milk powder and fresh cream), and filled milk (containing

skim milk powder and vegetable oils). Samples of cheese

prepared were evaluated by panels made up of Latin Ameri­

cans in the area (15 to 20 people per panel), most of whom

were acquainted with the cheeses produced in Mexico.

Analyses of all cheeses were made for percentages of

moisture, fat, lactose, and protein.

In general, the cheeses produced by Harper's pro­

cedure (in which the curds and whey were separated and

pressed without an interim cooking period) had a higher /•. • I

moisture content than cheeses prepared by the modified

procedures (54.75% compared to 48.15%). Cheeses made by

Harper's procedure were more difficult to press than those h :s manufactured by fr*te experimental method.

The cheese was extremely bland in flavor, slightly

crumbly, and possessed a "rubbery" texture. The keeping

quality averaged approximately 25 days at refrigerator

temperatures. Cheese made from nonhomogenized whole milk

was preferred to that from homogenized milk, mainly because

that made from homogenized milk was more difficult to pro­

cess, Panel ists preferred cheese made from whole milk to

that manufactured from either reconstituted or filled milk,

chiefly because of flavor. They indicated that cheese from

70

whole milk exhibited a "full, rich" flavor that the other

products did not have. They also indicated that Mexican

cheese should not only be bland, crumbly, and tough tex­

tured, but that it should possess good melting qualities.

Panel members preferred a product that would melt and flow,

rather than turn brown and crisp, upon cooking. In fact,

samples of filled milk cheese were criticized for lacking

this melting quality.

Accordingly, several batches of filled milk cheese

containing sodium citrate were prepared, and although the

melting qualities were improved, crumbly body characteris­

tics were destroyed. This vras a major reason for their

preference of whole milk cheese to any type of filled pro­

duct.

The panelists indicated that Mexican cheese could

probably be merchandised most successfully in circular

patty forms approximately 4^ inches in diameter, and one-

half inches thick. Five pound sizes of the product would

probably sell successfully to restaurant owners and other

commercial food establishments.

ttm

CHAPTER VII

CONCLUSIONS

The following conclusions were reached based on

the results of this study:

1. High quality Mexican cheese should have con­

siderable market value among the Latin American population,

based on a panel in the Lubbock, Texas, area,

2. Mexican cheese can be conveniently manufactured

in existing market milk operations with minor additions of

special equipment.

3. A more acceptable product can be manufactured

from non-homogenized, whole milk than can be expected from

homogenized milk, reconstituted milk, or filled milk.

4. The major attribute of Mexican cheese made

from whole milk by the experimental method developed in

this study was its full, rich flavor; however, the product

did not seem to have maximum desirability with respect to

body, texture, and ihelting qualities. Apparently, Latin

Americans would like a cheese which has a more crumbly,

tough texture than that developed in the experiment,

5. Mexican cheese made with filled milk can be

expected to have a desirable body, but may lack sufficient

melting qualities unless combinations of emulsifying salts

71

72

can be found to improve that quality without sacrificing

the crumbly body characteristic. Also, one can expect that

such a cheese would not have a full, sweet flavor so char­

acteristic of whole milk cheese,

6. Cheeses made by the experimental procedure were

superior to existing Mexican cheeses on the market, partly

attributable to the fact that those cheeses are made with

filled milks,

7. If Mexican cheese wore marketed, the most popu­

lar package probably would be a patty approximately four

inches in diameter and one inch thick since this is the

package for cheeses produced in Mexico.

8. Cheeses made by the experimental method were

superior to similar products made by Harper's method, in

that they were drier, more crumbly, less leaky, and pos­

sessed better keeping qualities.

or A.

LIST OF REFERENCES

1. Barcia, Evangelina M. Personal interview. Lubbock, Texas. March 17, 1968.

2. Davis, J, G. Cheese. American Elsevier Publishing Co., Inc., New York, pp, 30, 150, 260. 1965,

3. Eastham, Joe B. A Quantitative Method for Determinin the Supcar Content of Ice Cream. Unpublished Master's thesis, Texas Technological College, 1963.

4. Esparza, Manuel. Mexican Consulate, Lubbock, Texas. Personal interview, Lubbock, Texas. February 11, 1968.

5. Fatta, Louis, Kraft Foods, Mexico City, Mexico, Personal correspondence, February, 1968.

6. Foster, E. M. , Nelson, F. E. , Speck, M. L, , Doetsch, R, N, , and Olson, J. C. Dairy Microbiolopv. Prentice-Hall, Inc., New York. 1957.

7. Goss, E. F. Techniques of Dairy Plant Testing. The Iowa State College Press, Ames, Iowa. 1953.

8. Holden, Gladys K. and Lamb, Mina W. "Early Foods of the Southwest." The American Dietetic Association. 40:223, March, 1962,

9. Horwitz, William (ed.). Official Methods of Analysis of the Association of Official Agricultural Chemists. 9th ed. Association of Official Agricultural Chemists, Washington, D,C. pp. 12, 13, 210, 1960,

10, Kosikowski, Frank V. Cheese and Fermented Milk Foods. Cornell University, Ithaca, New York, pp, 142-152, 415. 1966.

11, Kraft Foods, The World of Cheese, Educational Depart­ment of Kraft Foods, Chicago, Illinois, page 4, 1958.

12i Meraz, Francisco. Queseria Latino, Ixtapalapa, Mexico, Personal correspondence. 1968.

13. National Dairy Council. Newer Knowledge of Cheese, National Dairy Council, Chicago, Illinois, page 8, 1968,

73

74

14, Panelist interviews. 1968,

15. Peeples, Milton L. Personal interview. Lubbock, Texas, 1968,

16. Sanders, George P. "Cheese Varieties and Descrip­tions." U. S. Dept. of Agriculture, Agr. Handbook No. 54. pp, 3, 99-101. 1953.

17, Siapantas, L. G, and Kosikowski, F. V, "Properties of Latin-American White Cheese as Influenced by Gla­cial Acetic Acid," Journal of Dairy Science. 50: 1589-1591. October, 1967.

18, Simon, Andre L. Cheeses of the World. Faber and Faber, London. pp. 177-184. 1965.

19, Takahashi, M, "Determination of Reducing Sugars by Means of Back Titration Against Alkaline Copper Solution," I. Bulletin of the Chemical Society of Japan, 33:178. 1960.

20. United States Department of Agriculture--Statistical Reporting Service. "Production of Manufactured Dairy Products." Crop Reporting Board, Washington, D, C, July, 1968,

21. Weigold, G. W, "Development of a Factory Method for the Manufacture of Queso del Pais," The Milk Pro­ducts Journal, 49:16-17, 25. October, 1958.

22, Wilster, G. H, Practical Cheesemaking, 9th ed, 0.S,C. Cooperative Association, Corvallis, Oregon. 1959.

23. Wilster, G. H, Practical Cheesemaking. 10th ed, 0,S,C. Cooperative Association, Corvallis, Oregon, 1964,