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Temperature-Programmed Cooking of Cottage Cheese1, 2, 3, 4
TEMPERATURE-PROGRAMMED COOKING OF C O T T A G E C H E E S E 1, 2, ~, 4 J. A. RAAB, JR.., B. J. IASKA, AN~) C. E. PARMELEE Department of Animal Sciences, Purdue University, Lafayette, Indiana SUMMARY
An automatic temperature-programmed procedure for cooking Cottage cheese curd was developed. The procedure worked equally well for small or large curd Cottage cheese. Cutting acidities of 0.60 to 0.62% for 10.25% solids skimmilk were necessary to prevent matting of the curd and to obtain maxinmm yield of Cottage cheese per pound of skimnfilk solids. The rapid cooking procedure was used to produce Cottage cheese which was comparable to Cottage cheese produced using conventional cooking procedures. This method of standardized cooking of Cottage cheese should save labor and improve the uniformity of the product.
Emmons (3, 4) has published excellent reviews of recent literature on Cottage cheese manfaeture. These reviews include major advances in methods to determine proper cutting time, to establish the endpoint of cooking, and to standardize the flavor of Cottage cheese. Few references were included concerning the cooking procedures for Cottage cheese, due to the lack of research in the area in recent years. The various cooking procedures now in use have been developed from practical experience. Several types of steam injectors or whey heaters have been introduced, but the cooking of Cottage cheese is still basically a manually controlled operation. Thermostatically controlled heating units for spray-type vats are available, but the temperature setting of the thermostat is advanced manually. 5[any factors are involved in the determination of the rate and temperature at which Cottage cheese will be cooked. The type of curd, size of curd, temperature of set, per cent of solids, source of milk, growth of culture, size of vat, acidity at cutting and firmness desired, all determine the cooking program (2, 3, 4). Collins (1) found considerable variation in Cottage cheese cooking procedures in California 7Received for publication March 5, 1964. Published with the approval of the Director of the Purdue Agricultural Experiment Station as Journal Series Paper Number 2312. 2j. A. Raab, Jr., Borden Company, Columbus, Ohio. 3Data presented are based on a thesis by J. A. Raab, Jr. in partial fulfillment of the requiremerits for a h~aster of Science degree. 4 Supported in part by a grant from the American Dairy Association.
dairy plants and indicated that cooking procedures could be varied by adjusting factors affecting expulsion of whey by heat. This suggests that if most factors influencing whey expulsion are held constant, then a standard cookblg procedure could be developed. The objective of this research was to investigate the use of automatic controls for developing a standard procedure for temperature-programmed cooking of Cottage cheese. METItODS
Cultures.
One single-strain and three mixedstrain lactic cultures were obtained from stock cultures maintained in the Dairy Manufacturing Section at Purdue University. The cultures used in all experiments were propagated in skimmilk containing 10.25% solids, and sterilized by autoclaving at ]20 C for 15 rain. Source of .milk. Grade A skimmilk was obtained from the Purdue University Creame~5~. Milk solids for reconstituted fortified skimmilk were obtained from Grade A low-heat nonfat dry milk from a reputable manufacturer. Analysis for total solids. Total solids of skimmilk, whey, and wash water were determined by the Mojonnier method (7). The Cottage cheese curd was macerated in a blender, weighed into a conditioned NIojonnier solids dish, and heated in an atmospheric oven at 100 C for 24 hr. The dish and solids were conditioned and reweighed. Manufacturing proced~res. The skinmfilk used for the manufacture of Cottage cheese was pasteurized at 145 F for 30 rain, or 163 F for 16 see, cooled, placed in a cheese vat, and adjusted to 72 F. One per cent by weight of an active lactic culture was added. After 30 rain,
612
COOKING
613
COTTAGE CHEESE
rennet was added at the rate of 1 ml per 1,000 lb of skinnnilk. The rennet was diluted with 30 to 40 volumes of cold water before being added to the milk. The skimmilk, culture, and rennet were thoroughly mixed by hand or mechanical agitation. The skimmilk was allowed to remain quiescent until coagulation took place 12-16 hr after addition of the culture. The titratable acidity of the clear whey was used to determine cutting time. The A-C endpoint was determined periodically for comparison. The curd was cut into one-fourth-inch cubes for small-curd or one-half-inch cubes for large-curd Cottage cheese. Manual coolcing procedure. The curd was not disturbed for 20 mAn after cutting, to permit slight firming. The temperature of the water in the jacket was maintained manually at 20 to 25 F above the temperature of the vat contents during cooking, and the curd was stirred only enough to prevent matting until a temperature of 90 to 9 5 F was reached. For the remainder of the cooking period, agitation was continuous. The final cooking temperature of 124 to 128 F was reached in 2 to 2.5 hr after cutting. The curd was held in the hot whey until the desired firmness was attained, as determined by the Wisconsin Curd Meter (5). The whey was drained to the level of the curd. Water at 60 F was added to bring the vat contents back to the normal level and the temperature down to 80 to 90F. The curd was not agitated until all water was added. After a 10man holding time, the wash water was drained completely and 40 to 45 F water was added to bring the temperature of the vat contents down to 55 to 60 F. Following another 10-mAn holding time, the second wash water was drained and the curd was trenched and allowed to drain for 1 hr. At the end of the draining period, the weight was determined, a sample was taken for moisture analysis, and two 12-oz cartons of Cottage cheese were creamed for quality evaluation by trained judges.
BROWNCAM-TYPE ~ PROGRAM CONTROLLER
~ o
REGULATED A~R SUPPLY TO DIAPHRAGM VALVE AIR SUPPLYRT%0
C.EEBE VAT ~
STEAM LINE TO CHEESE VAT
WATER
FIG.
1.
I
~S.'. I
Diagram
of
installation
for
Minne-
~polls-]=[oneywellcam-type program controller with dual pneumatic controller Mode] No. R602P43DD-96-III-671. The whey reached a temperature of 138 F in 80 man after cutting for both large- and smallcurd Cottage cheese. The temperature was held at 138 F for 10 man under normal conditions or until the curd was sufficiently firm, as determined by the Wisconsin Curd Meter (5). The curd was washed in the same way as the manually cooked curd. After draining, the weight was determined, a sample was taken for moisture determination, and two 12-oz cartons of Cottage cheese were creamed for quality evaluation by trained judges. Cottage cheese scori~g. Two experienced judges from the staff of the Dairy Manufacturing Section scored the samples for flavor, body, texture, appearance, and color, using the official score card recommended by the American Dairy Science Association. RESULTS
AND
DISCUSSION
Temperature-programmed sequence. After preliminary experimental work,
t60
WATER JACKET TEMPERATURE
---
I SO
Temperature-programmed cooking procedure.
i40
Instrumentation for control of the cooking operation, using a M i n n e a p o l i s - H o n e y w e l l Model No. I R 602P43-DD-96-111-671 program controller, is diagrannned in Figure 1. The temperature of the water in the jacket was raised to 110 to 118 F just prior to cutting the curd, held at 110 to 118 F for 10 mAn, increased at a uniform rate to 165 F during 55 mAn, and held at 165 F for 15 mAn. The curd was stirred by hand 10 and 20 man after cutting and then each 5 man until the whey reached a temperature of 90 to 95 F. Then the vats were agitated continuously, either by hand or mechanically.
p. I"40
VAT CONTENTS TEMPERATURE // /
,oo
standard
/o-- -/
/ //
\
/
\ \\
/
/ / o--o/
~ulo
a
;
,/"
/ /
'l
/
I
I
so
c
70
I ?
,
,
o
Io
20
/
/
,
,
/
STOP o ,
30 4o
,
,
50 so
70
,
h~
eo 9o
,
Ioo
TIME IN MINUTES
FIG. 2.
Relation of water jacket temperature to cooking temperature of Cottage cheese using the automatic programmed temperature sequence.
614
J. A. RAAB, JR., B. J. L I S K A , A N D C. E. P A R M E L E E
automatic temperature-p r o g r a m m e d cooking procedure was developed (Figure 2). l~{aximum rates of heating were determined by physical observation of the curd. When heating was started before cutting, temperatures up to 118 F did not appreciably affect Cottage cheese quality. Large- and small-curd Cottage cheese cooked out well using the automatic temperature-programmed cooking procedure when both were cut at 0.60 to 0.62% titratable acidity for 10.25% solids skimmilk. Acid development after cutting was limited to an increase of 0.02% in the titratable acidity of the clear whey. Curd cut at 0.54% titratable acidity tended to mat excessively when rapidly heated. ~Iatring was not a problem when the curd was cut at 0.60 to 0.62% titratable acidity for 10.25% solids skimmilk. The curd tended to float when the cutting acidities were higher than 0.62% and when the water in the jacket before cutting was heated higher than 118 F. Cottage cheese cut at higher titratable acidities cooked out normally when water was added to the vat to reduce the titratable acidity of the whey to 0.60 to 0.62%. Floating and wet-appearing curd associated with high cutting acidities was eliminated when water was added to the vat. This indicated that the acidity of the cooking medium was involved in determining the cooking procedure to be followed. Cottage cheese yield. All data reported in this section are from 10.25% solids skimmilk. The per cent solids in the skimmilk was determined by the Mojonnier method (7). All vats of Cottage cheese were weighed to determine yield, and the yield of cheese was corrected to 80% moisture. The weight of curd per pound of solids was calculated as described by Kosikowski (6). This weight was then plotted against the per cent acidity of the clear whey at 102 to 105 F. The maximum yield of Cottage cheese curd was obtained when the titratable acidity of the whey was 0.64% as the whey temperature reached 102 to 105 F (Figure 3). Total solids of whey from vats of cheese with various whey acidities at the cooking temperature reached 102 to 105 F were determined. The relation of solids in the whey to whey acidity is shown in Figure 4. As the titratable acidity of the whey at 102 to 105 F increased to 0.64%, the per cent solids in the whey decreased. Low solids in the whey and high yields of Cottage cheese occurred at the same titratable acidity of 0.64%. When the acidity of the whey increased from 0.53 to
1.90 O
~ I.so
~ ~ ~ ~ o
~ 1.7o = ~ 1.6o ¢~ ,.5o ~ 1.4o
/ I
I
I
I
I
0.50
0.55
0.60
0.65
0.70
TITRATABLE
ACIDITY
OF CLEAR
AT 102° -
WHEY
I 0 5 ° F.
FIG. 3. Relation of yield of Cottage cheese to whey. acidity. 0.64%, the yield of C~ttage cheese curd increased from 1.47 to 1 . : . ~b curd per pound of milk solids. The solids lost in the whey decreased from 7.45 to 7.21% when the cutting acidity increased from 0.53 to 0.64%. This amounted to an increase of 1.20 lb of Cottage cheese per 100 lb of whey. Flavor~ body, and texture. Thirty-one lots of Cottage cheese were made and scored for flavor, body and texture, appearance and color. The results are summarized in Table 1. The average total score for the samples made by the manual cooking procedure was 89.6, as compared to an average score of 89.3 for the samples made by the temperature-programmed
~- e . 0 o z ~ 7.5o Q--D
°~°
i--
~ "r.OO ~" a. I
0,50
I
0.55
I
0.60
TITRATABLE
I
0.65
I
0,70
ACIDITY
FIG. 4. Relation of solids level to whey acidity at 102 to 105 F for 1.0.25% solids skimmilk.
COOKING COTTAGE CHEESE TABLE 1 Comparison of average scores of 31 lots of Cottage cheese made with automatic programmed and manual control of heating during the cooking operation
Type of heating Manual control : Small curd a Temperature programming : Small curd ~ Large curd ~
AppearTexture ance and and Total Flavor body color score d 37.9
28.1
18.5
89.6
37.8 37.5
28.0 28.3
18.5 18.3
89.3 89.3
a Eleven vats of cheese (50-gal. size). b Eleven vats of cheese (50-gal. size). " Nine vats of cheese (300-gal. size). d Includes five points for package.
cooking procedures. The r a p i d cooking p r o cedure followed was effective in r e m o v i n g the acid f r o m the curd even at the high cutting acidities used, with few samples being scored down f o r an acid flavor defecL. The scores were low by both methods, due to use of small vats and e x p e r i m e n t a l techniques.
615
ACKNO~VLEDGI~IEh!T The authors thank the Minneapolis-ttoneywell Regulator Company for the use of the temperature programming controls during this study. REFERENCES (1) CenLINS, E. B. Resistance of Certain Bacteria to Cottage Cheese Cooking Procedures. J. Dairy Sei., 44: 1989. 1961. (2) CORDES, W. A. Factors Affecting the Yield of Cottage Cheese. J. Dairy Sei., 42: 2012. 1959. (3) E ~ o N s , D. B. Recent Research in the Manufacture of Cottage Cheese. P a r t I. Dairy Sci. Abstrs., 25(4) : 130. 1963. (4) E ~ O N S , D. B. Recent Research in the Manufacture of Cottage Cheese. P a r t II. Dairy Sci., 42: 533. 1959. (5) E ~ I o N s , D. B., AND P~ICE, W. V. A Curd :~irmness Test for Cottage Cheese. J. Dairy Scl. Abstrs., 25(4) : 275. 1963. (6) KOSIKOWSKI, F. V. Better Cottage Cheese Through Control of Curd Losses and Defects. Proc. 52nd Ammal Convention. pp. 2-8. International Association of Milk Dealers, Miami Beach, Florida. October 7-9, ]959. (7) MOJONNIER, T., AND TROY, I-I. C. The Technical Control of Dairy Products. Mojonnier Bros. Co., Chicago. 1922.
An automatic temperature-programmed procedure for cooking Cottage cheese curd was developed. The procedure worked equally well for small or large curd Cottage cheese. Cutting acidities of 0.60 to 0.62% for 10.25% solids skimmilk were necessary to prevent matting of the curd and to obtain maxinmm yield of Cottage cheese per pound of skimnfilk solids. The rapid cooking procedure was used to produce Cottage cheese which was comparable to Cottage cheese produced using conventional cooking procedures. This method of standardized cooking of Cottage cheese should save labor and improve the uniformity of the product.
Emmons (3, 4) has published excellent reviews of recent literature on Cottage cheese manfaeture. These reviews include major advances in methods to determine proper cutting time, to establish the endpoint of cooking, and to standardize the flavor of Cottage cheese. Few references were included concerning the cooking procedures for Cottage cheese, due to the lack of research in the area in recent years. The various cooking procedures now in use have been developed from practical experience. Several types of steam injectors or whey heaters have been introduced, but the cooking of Cottage cheese is still basically a manually controlled operation. Thermostatically controlled heating units for spray-type vats are available, but the temperature setting of the thermostat is advanced manually. 5[any factors are involved in the determination of the rate and temperature at which Cottage cheese will be cooked. The type of curd, size of curd, temperature of set, per cent of solids, source of milk, growth of culture, size of vat, acidity at cutting and firmness desired, all determine the cooking program (2, 3, 4). Collins (1) found considerable variation in Cottage cheese cooking procedures in California 7Received for publication March 5, 1964. Published with the approval of the Director of the Purdue Agricultural Experiment Station as Journal Series Paper Number 2312. 2j. A. Raab, Jr., Borden Company, Columbus, Ohio. 3Data presented are based on a thesis by J. A. Raab, Jr. in partial fulfillment of the requiremerits for a h~aster of Science degree. 4 Supported in part by a grant from the American Dairy Association.
dairy plants and indicated that cooking procedures could be varied by adjusting factors affecting expulsion of whey by heat. This suggests that if most factors influencing whey expulsion are held constant, then a standard cookblg procedure could be developed. The objective of this research was to investigate the use of automatic controls for developing a standard procedure for temperature-programmed cooking of Cottage cheese. METItODS
Cultures.
One single-strain and three mixedstrain lactic cultures were obtained from stock cultures maintained in the Dairy Manufacturing Section at Purdue University. The cultures used in all experiments were propagated in skimmilk containing 10.25% solids, and sterilized by autoclaving at ]20 C for 15 rain. Source of .milk. Grade A skimmilk was obtained from the Purdue University Creame~5~. Milk solids for reconstituted fortified skimmilk were obtained from Grade A low-heat nonfat dry milk from a reputable manufacturer. Analysis for total solids. Total solids of skimmilk, whey, and wash water were determined by the Mojonnier method (7). The Cottage cheese curd was macerated in a blender, weighed into a conditioned NIojonnier solids dish, and heated in an atmospheric oven at 100 C for 24 hr. The dish and solids were conditioned and reweighed. Manufacturing proced~res. The skinmfilk used for the manufacture of Cottage cheese was pasteurized at 145 F for 30 rain, or 163 F for 16 see, cooled, placed in a cheese vat, and adjusted to 72 F. One per cent by weight of an active lactic culture was added. After 30 rain,
612
COOKING
613
COTTAGE CHEESE
rennet was added at the rate of 1 ml per 1,000 lb of skinnnilk. The rennet was diluted with 30 to 40 volumes of cold water before being added to the milk. The skimmilk, culture, and rennet were thoroughly mixed by hand or mechanical agitation. The skimmilk was allowed to remain quiescent until coagulation took place 12-16 hr after addition of the culture. The titratable acidity of the clear whey was used to determine cutting time. The A-C endpoint was determined periodically for comparison. The curd was cut into one-fourth-inch cubes for small-curd or one-half-inch cubes for large-curd Cottage cheese. Manual coolcing procedure. The curd was not disturbed for 20 mAn after cutting, to permit slight firming. The temperature of the water in the jacket was maintained manually at 20 to 25 F above the temperature of the vat contents during cooking, and the curd was stirred only enough to prevent matting until a temperature of 90 to 9 5 F was reached. For the remainder of the cooking period, agitation was continuous. The final cooking temperature of 124 to 128 F was reached in 2 to 2.5 hr after cutting. The curd was held in the hot whey until the desired firmness was attained, as determined by the Wisconsin Curd Meter (5). The whey was drained to the level of the curd. Water at 60 F was added to bring the vat contents back to the normal level and the temperature down to 80 to 90F. The curd was not agitated until all water was added. After a 10man holding time, the wash water was drained completely and 40 to 45 F water was added to bring the temperature of the vat contents down to 55 to 60 F. Following another 10-mAn holding time, the second wash water was drained and the curd was trenched and allowed to drain for 1 hr. At the end of the draining period, the weight was determined, a sample was taken for moisture analysis, and two 12-oz cartons of Cottage cheese were creamed for quality evaluation by trained judges.
BROWNCAM-TYPE ~ PROGRAM CONTROLLER
~ o
REGULATED A~R SUPPLY TO DIAPHRAGM VALVE AIR SUPPLYRT%0
C.EEBE VAT ~
STEAM LINE TO CHEESE VAT
WATER
FIG.
1.
I
~S.'. I
Diagram
of
installation
for
Minne-
~polls-]=[oneywellcam-type program controller with dual pneumatic controller Mode] No. R602P43DD-96-III-671. The whey reached a temperature of 138 F in 80 man after cutting for both large- and smallcurd Cottage cheese. The temperature was held at 138 F for 10 man under normal conditions or until the curd was sufficiently firm, as determined by the Wisconsin Curd Meter (5). The curd was washed in the same way as the manually cooked curd. After draining, the weight was determined, a sample was taken for moisture determination, and two 12-oz cartons of Cottage cheese were creamed for quality evaluation by trained judges. Cottage cheese scori~g. Two experienced judges from the staff of the Dairy Manufacturing Section scored the samples for flavor, body, texture, appearance, and color, using the official score card recommended by the American Dairy Science Association. RESULTS
AND
DISCUSSION
Temperature-programmed sequence. After preliminary experimental work,
t60
WATER JACKET TEMPERATURE
---
I SO
Temperature-programmed cooking procedure.
i40
Instrumentation for control of the cooking operation, using a M i n n e a p o l i s - H o n e y w e l l Model No. I R 602P43-DD-96-111-671 program controller, is diagrannned in Figure 1. The temperature of the water in the jacket was raised to 110 to 118 F just prior to cutting the curd, held at 110 to 118 F for 10 mAn, increased at a uniform rate to 165 F during 55 mAn, and held at 165 F for 15 mAn. The curd was stirred by hand 10 and 20 man after cutting and then each 5 man until the whey reached a temperature of 90 to 95 F. Then the vats were agitated continuously, either by hand or mechanically.
p. I"40
VAT CONTENTS TEMPERATURE // /
,oo
standard
/o-- -/
/ //
\
/
\ \\
/
/ / o--o/
~ulo
a
;
,/"
/ /
'l
/
I
I
so
c
70
I ?
,
,
o
Io
20
/
/
,
,
/
STOP o ,
30 4o
,
,
50 so
70
,
h~
eo 9o
,
Ioo
TIME IN MINUTES
FIG. 2.
Relation of water jacket temperature to cooking temperature of Cottage cheese using the automatic programmed temperature sequence.
614
J. A. RAAB, JR., B. J. L I S K A , A N D C. E. P A R M E L E E
automatic temperature-p r o g r a m m e d cooking procedure was developed (Figure 2). l~{aximum rates of heating were determined by physical observation of the curd. When heating was started before cutting, temperatures up to 118 F did not appreciably affect Cottage cheese quality. Large- and small-curd Cottage cheese cooked out well using the automatic temperature-programmed cooking procedure when both were cut at 0.60 to 0.62% titratable acidity for 10.25% solids skimmilk. Acid development after cutting was limited to an increase of 0.02% in the titratable acidity of the clear whey. Curd cut at 0.54% titratable acidity tended to mat excessively when rapidly heated. ~Iatring was not a problem when the curd was cut at 0.60 to 0.62% titratable acidity for 10.25% solids skimmilk. The curd tended to float when the cutting acidities were higher than 0.62% and when the water in the jacket before cutting was heated higher than 118 F. Cottage cheese cut at higher titratable acidities cooked out normally when water was added to the vat to reduce the titratable acidity of the whey to 0.60 to 0.62%. Floating and wet-appearing curd associated with high cutting acidities was eliminated when water was added to the vat. This indicated that the acidity of the cooking medium was involved in determining the cooking procedure to be followed. Cottage cheese yield. All data reported in this section are from 10.25% solids skimmilk. The per cent solids in the skimmilk was determined by the Mojonnier method (7). All vats of Cottage cheese were weighed to determine yield, and the yield of cheese was corrected to 80% moisture. The weight of curd per pound of solids was calculated as described by Kosikowski (6). This weight was then plotted against the per cent acidity of the clear whey at 102 to 105 F. The maximum yield of Cottage cheese curd was obtained when the titratable acidity of the whey was 0.64% as the whey temperature reached 102 to 105 F (Figure 3). Total solids of whey from vats of cheese with various whey acidities at the cooking temperature reached 102 to 105 F were determined. The relation of solids in the whey to whey acidity is shown in Figure 4. As the titratable acidity of the whey at 102 to 105 F increased to 0.64%, the per cent solids in the whey decreased. Low solids in the whey and high yields of Cottage cheese occurred at the same titratable acidity of 0.64%. When the acidity of the whey increased from 0.53 to
1.90 O
~ I.so
~ ~ ~ ~ o
~ 1.7o = ~ 1.6o ¢~ ,.5o ~ 1.4o
/ I
I
I
I
I
0.50
0.55
0.60
0.65
0.70
TITRATABLE
ACIDITY
OF CLEAR
AT 102° -
WHEY
I 0 5 ° F.
FIG. 3. Relation of yield of Cottage cheese to whey. acidity. 0.64%, the yield of C~ttage cheese curd increased from 1.47 to 1 . : . ~b curd per pound of milk solids. The solids lost in the whey decreased from 7.45 to 7.21% when the cutting acidity increased from 0.53 to 0.64%. This amounted to an increase of 1.20 lb of Cottage cheese per 100 lb of whey. Flavor~ body, and texture. Thirty-one lots of Cottage cheese were made and scored for flavor, body and texture, appearance and color. The results are summarized in Table 1. The average total score for the samples made by the manual cooking procedure was 89.6, as compared to an average score of 89.3 for the samples made by the temperature-programmed
~- e . 0 o z ~ 7.5o Q--D
°~°
i--
~ "r.OO ~" a. I
0,50
I
0.55
I
0.60
TITRATABLE
I
0.65
I
0,70
ACIDITY
FIG. 4. Relation of solids level to whey acidity at 102 to 105 F for 1.0.25% solids skimmilk.
COOKING COTTAGE CHEESE TABLE 1 Comparison of average scores of 31 lots of Cottage cheese made with automatic programmed and manual control of heating during the cooking operation
Type of heating Manual control : Small curd a Temperature programming : Small curd ~ Large curd ~
AppearTexture ance and and Total Flavor body color score d 37.9
28.1
18.5
89.6
37.8 37.5
28.0 28.3
18.5 18.3
89.3 89.3
a Eleven vats of cheese (50-gal. size). b Eleven vats of cheese (50-gal. size). " Nine vats of cheese (300-gal. size). d Includes five points for package.
cooking procedures. The r a p i d cooking p r o cedure followed was effective in r e m o v i n g the acid f r o m the curd even at the high cutting acidities used, with few samples being scored down f o r an acid flavor defecL. The scores were low by both methods, due to use of small vats and e x p e r i m e n t a l techniques.
615
ACKNO~VLEDGI~IEh!T The authors thank the Minneapolis-ttoneywell Regulator Company for the use of the temperature programming controls during this study. REFERENCES (1) CenLINS, E. B. Resistance of Certain Bacteria to Cottage Cheese Cooking Procedures. J. Dairy Sei., 44: 1989. 1961. (2) CORDES, W. A. Factors Affecting the Yield of Cottage Cheese. J. Dairy Sei., 42: 2012. 1959. (3) E ~ o N s , D. B. Recent Research in the Manufacture of Cottage Cheese. P a r t I. Dairy Sci. Abstrs., 25(4) : 130. 1963. (4) E ~ O N S , D. B. Recent Research in the Manufacture of Cottage Cheese. P a r t II. Dairy Sci., 42: 533. 1959. (5) E ~ I o N s , D. B., AND P~ICE, W. V. A Curd :~irmness Test for Cottage Cheese. J. Dairy Scl. Abstrs., 25(4) : 275. 1963. (6) KOSIKOWSKI, F. V. Better Cottage Cheese Through Control of Curd Losses and Defects. Proc. 52nd Ammal Convention. pp. 2-8. International Association of Milk Dealers, Miami Beach, Florida. October 7-9, ]959. (7) MOJONNIER, T., AND TROY, I-I. C. The Technical Control of Dairy Products. Mojonnier Bros. Co., Chicago. 1922.