Manufacture of Colby and Brick Cheeses from Ultrafiltered Milk

Manufacture of Colby and Brick Cheeses from Ultrafiltered Milk C. S. BUSH, C. A. CAROUTTE, C. H. AMUNDSON, and N. F. OLSON Department of Food Science University of Wisconsin Madison, Wl 53706 ABSTRACT

Skim milk was fractionated to attain a 50% volume reduction by ultrafihration, standardized with cream, and used in the manufacture of brick and Colby cheeses. The traditional curd washing step was eliminated from the manufacturing procedures. Brick cheese made from creamed skim milk retentate exhibited a lower pH and higher whey-fat loss than control cheese. It was more firm and mealy, possessed a greater acid flavor and less intense cheese flavor, and ranked lower in overall preference than control cheese in evaluation by expert graders. Higher whey-fat losses but similar pH were obtained with Colby cheese prepared from creamed skim milk retentate as compared to control cheese. Evaluation by a sensory analysis panel indicated no differences in overall preference between experimental cheese at an age of 3 mo as compared to commercial Cheddar and " Colby cheeses of similar age. Reductions in cooking temperature and milk-clotting enzyme and elimination of curd-washing were achieved. INTRODUCTION

Increased cheese yield and savings in energy, milk-clotting enzymes, manufacturing time, and whey disposal have evoked an interest in the use of milk pretreated by ultrafihration (UF) for cheese making (6, 15, 17). Success attained in manufacturing cheese from whole milk retentate or skim milk retentate to which cream is added has depended upon the degree of retentate concentration and the type of cheese being made. Ultrafiltration of milk to protein equivalent to that of a soft or semisoft cheese has given products with acceptable body and

Received July 6, 1982.

1983 J Dairy Sci. 66:415-421

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flavor characteristics (2, 3, 13, 15, 16, 17). A similar retentate to manufacture hard type cheeses has not been successful in producing cheese with body and flavor characteristics comparable to a product prepared in the traditional manner (3). Production of an acceptable hard cheese has been limited to milk partially fractionated by UF with the subsequent cheese manufacturing process involving some cooking of the curd and whey drainage (2). Recently Kosikowski (11) reconstituted creamed retentates to various fat and protein percents for use in the manufacture of Cheddar cheese. Cheeses initially were similar to traditional Cheddar in flavor and body, but during ripening a rapid rise in pH, eye formation, and development of a sweet flavor resembling Swiss cheese occurred. This study was to develop procedures suitable for the manufacture of brick and Colby cheeses from milk fractionated by UF to remove a portion of the water and milk constituents traditionally removed in the whey. The methods were selected to be economical, to allow the use of traditional cheesemaking equipment, to integrate with on-farm milk ultrafiltration (9, 18, 19, 20), and to eliminate the need for traditional curd-washing treatment to control the final pH of these cheeses which would eliminate a waste stream f ~ m cheese plants. MATERIALS AND METHODS

Retentate Preparation

Raw skim milk from the University of Wisconsin Dairy Plant was fractionated with a Romicon HF 2SSS UF unit as described by Garoutte et al. (7). The system contained two PM50 membranes with a molecular weight cut-off of 50,000 dahons and a total membrane area of 3.86 m 2 . Inlet and outlet pressures were 2.11 and .70 kg/cm 2. Milk was heated to 57.2°C before processing and held at that temperature during UF. Recirculation of milk

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BUSH ET AL.

through the system continued until a 50% reduction of the original milk volume was reached. Brick Cheese Manufacture

Raw cream was added to the retentate to give a mixture with a casein to fat ratio of .68. This mixture was pasteurized at 62.8°C for 30 rain and then cooled to 31.1°C. Lactic starter (Marschall Brand, Marschall Division, Miles Laboratories, Madison, WI) at .39% and single strength calf rennet (Rennet Extract, Marschall Division, Miles Laboratories, Madison, WI) at 9.1 ml/45 kg of mixture were added simultaneously to the creamed retentate. The curd was cut with .61-cm wire knives 20 to 25 rain after rennet addition and allowed to remain undisturbed for 5 min after cutting. Heating commenced 15 rain after cutting and 15 min were required to reach a cooking temperature of 32.8°C. This temperature was maintained for 40 min. Whey drainage, dipping of curd and whey into draining hoops, and subsequent handling of the curd blocks followed the procedure of Price and Buyens (18). A control vat of cheese was prepared by the procedure of Price and Buyens (18), which included a curd washing treatment. Starter .31% and cooking temperature of 29.2°C were used. Colby (Stirred Curd) Cheese Manufacture

Raw cream was added to the skim milk retentate to give a mixture with a casein to fat ratio of .60. This mixture was pasteurized at 62.8°C for 30 min and then cooled to 31.1°C. The creamed retentate was ripened for 1 h with 2.6% lactic starter (Marschall Brand, Marschall Division, Miles Laboratories, Madison, WI). Annatto color (Marschall Division, Miles Laboratories, Madison, WI) and a 1:1 mixture of single strength calf rennet (Rennet Extract, Marschall Division, Miles Laboratories, Madison, WI) and single strength microbial rennet (Marzyme, Marschall Division, Miles Laboratories, Madison, WI) were added at 5.8 and 8.0 ml/45 kg of creamed retentate, respectively. The curd was cut with .61-cm wire knives 25 rain after rennet addition and was allowed to remain undisturbed for 5 rain. Cooking commenced 15 rain after cutting, and the temperature was Journal of Dairy Science Vol. 66, No. 3, 1983

raised to 32.8°C over 15 min. Whey was drained from the curd 50 rain after the cooking temperature was reached. Salt (Cheese Salt, Diamond Crystal Salt Co., St. Clair, MI) was applied to the curd when it reached pH 5.70. The curd then was hooped and pressed overnight at 103.5 kPa. The cheese was aged at 7.2°C. A control vat of cheese was manufactured by the procedure of Wilster (22). The cheese was made with 1% lactic starter, cutting the curd with .61-cm knives, and cooking the curd to 28.9°C before cooling to 30.6°C during washing. Analysis and Grading

Cheeses were sampled for analysis at 1 wk. Fat contents of cream, retentate, and cheese were determined by Babcock test (14). The Pennsylvania modification of the Babcock Test (14) was used in testing for concentrations of fat in skim milk and whey. Moisture in cheese was measured by drying in a forced draft oven at l l 0 ° C for 16 h (21). The pH of cheese was measured by the quinhydrone method (21). Salt was measured by direct titration of chloride as described by Dixon (5). Brick and Colby cheeses were graded at an age of 5 wk by a panel of five expert judges. Cheeses were evaluated for acidity, bitterness, off-flavor intensity, firmness, mealiness, and overall preference. Colby cheeses also were evaluated at an age of 3 mo by a panel of 27 individuals experienced in sensory analysis. The experimental cheeses were judged against a commercial Colby cheese and a stirred-curd Cheddar cheese of similar age, manufactured in the University of Wisconsin Dairy Plant. The same characteristics as previously mentioned were used for the sensory evaluation panel. The sensory analysis procedures used and the method of data analysis were those of Lindsay et al. (12). RESULTS A N D DISCUSSION Brick Cheese

A 15% savings in starter and a 45% reduction in rennet were achieved by milk fractionated by UF. The reduced rennet requirement has been cited widely (2, 13, 17). The lower starter requirement has not been reported, and in our subsequent work with Colby cheese no savings

CHEESE FROM ULTRAFILTERED MILK in starter were found. A cooking temperature of 32.8°C was sufficient to attain the proper moisture content in cheese made from ultrafiltered milk. This was much less than 39.2°C used for the control and resulted from removal of milk serum during UF. TypicaI composition of brick cheese manufactured from creamed retentate and a control cheese made from creamed skim milk is in Table 1. Composition of the experimental cheese was similar to the control except for a lower pH in the former. The lower pH apparently was caused by insufficient lactose removal from the milk during UF, which resulted in excess acid production in the cheese during initial stages of ripening, This may be avoided by diafiltration of the retentate or washing the curd with a reduced amount of water. Fat loss in the whey was approximately 40% greater with cheese made from creamed retentate as compared to creamed skim milk after correction for differences in whey volume (Table 1). Substantial fat loss in the whey of cheese made from milk fractionated by UF also was reported by Green et al. (9). The cause of this excessive fat loss may be related to several factors. At the National Institute for Research in Dairying, it was found that cheese prepared from milk retentate concentrated more than twofold resulted in poorer association of the fat

TABLE 1. Composition and yield of cheese and fat loss in whey from brick cheese manufacturing trials using regular and UF (ultrafiltered) fractionated milk.

% Fat % H20 % FDM (fat dry matter) pH (at 7 days) % Fat in whey I Yield2

Control

Experimental (UF)

30.0 42.2

30.0 41.8

51.9 5.25 .45 11,0

51.6 5.10 .63 10.7

1Fat concentration was adjusted to achieve equivalency so that percentages are based upon the normal volume of whey from cheesemaking. 2Yield corrected for moisture is based upon following formula: kg Cheese × 100/(Original Weight of Skim Milk Before UF Fractionation + Weight of Cream).

417

and protein phases on a microscopic level (1). Dalgleish (4) suggested that reduced rennet acting on increasingly concentrated milks resulted in progressively smaller portions of casein becoming involved in curd formation at clotting. Less casein also may be incorporated in the curd matrix at cutting, which could result in less fat entrapment in the curd. Green et al. (9) substantiated this possibility by showing that the degree of aggregation of casein micelles at cutting decreased almost linearly as milk retentate concentration increased from an unconcentrated control to a fourfold concentrate. The proportion of fat retained in the cheese decreased over this range. Some of the excessive fat loss in the whey also may have resulted from difficulties in handling curd after cutting. The high concentrations of fat and protein and low volume of serum in the retentate created a large volume of curd and slow expulsion of whey after cutting. Curd particles also tended to aggregate at this point because of lack of whey surrounding them. This made it difficult to stir the curd for the first 10 to 15 min after cutting. Abrasion of the curd during this period probably contributed to increased fat loss and lower cheese yield from the concentrated milk. Criticisms during sensory evaluation of the brick cheeses were similar to those in previous reports on cheese made from ultrafiltered milk (3, 13). The experimental cheese was more firm and mealy than the control. It exhibited a more acid flavor and less cheese flavor and ranked lower in overall preference than cheese made from unconcentrated milk. Colby Cheese

Reductions in cooking temperature and milk-clotting enzyme similar to those with the brick cheese were made in the manufacture of Colby cheese from ultrafiltered milk. A mixture 1:1 of calf and microbial rennets was used to attain greater proteolysis during aging and possibly produce smoother textural characteristics as compared to that attained with calf rennet in the brick cheese made from ultrafiltered milk (8). The ratio of casein to fat of the creamed retentate was reduced to .60 versus .68 in the control to increase the fat in dry matter of cheese to obtain a smoother texture.

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Composition of a typical Colby cheese manufactured from creamed retentate and a control cheese made from creamed skim milk is in Table 2. The pH of cheese made from creamed retentate was satisfactory, indicating that the amount of lactose removal during UF was sufficient to control acid production. Applying crystalline salt to curd before hooping and pressing probably retarded acid production during the initial stages of aging in contrast to brine-salting of the brick cheese. Fat losses in the whey were excessive during manufacture of Colby cheese from creamed retentates (Table 2). Presumably the same causative factors as in manufacturing of brick cheese produced this loss. The higher yield of cheese per milk volume and per kilogram of solids probably resulted from the higher ratio of fat to casein in the creamed retentate as compared to the control milk. Because a much greater proportion of fat (about 90%) is retained in curd as compared to solids-not-fat retention (about 35%), the yield from the uhrafihered milk should be higher in spite of the higher fat loss. The effect of the loss of fat is reflected in the lower yield per kilogram of fat. Evaluation of Colby cheeses after 5 wk by five expert judges indicated that cheeses made from creamed retentate were more similar to stirred-curd Cheddar cheese than to commercial Colby cheese. The similarity to Cheddar resulted

from flavor characteristics, less openness, and firmer body of the experimental cheeses. Mealiness was much less evident in the experimental Colby cheese than it had been in the brick cheese made from uhrafiltered milk. This may have been from the higher ratio of fat to casein in UF milk and the addition of a mixture of calf and microbial rennets, which should have caused greater proteolysis in the Cheese during ripening (8). Colby cheeses were evaluated at an age of 3 mo by a sensory analysis panel; mean scores and statistical analysis of the data are in Table 3. Cheese produced in experimental trial 1 compared most closely to the University of Wisconsin Dairy Plant Cheddar in bitterness, cheese flavor, and off-flavor intensity. Experimental trial 2 was most similar to the commercial Colby cheese in acidity, bitterness, and cheese flavor. The uniformity of color and cheese firmness varied with each sample. The two cheeses prepared from concentrated milk retentates evaluated by the panel differed in several characteristics. Cheese of trial 1 was higher in moisture than that of trial 2, which may have resulted in its being judged more bitter and acid. Although experimental cheeses were rated slightly lower in overall preference than reference samples, the differences were not statistically significant at 5% probability. The present study indicates the potential for

TABLE 2. Composition and yield of cheese and fat loss in whey from Colby cheese manufacturing trials using regular and UF (ultra filtered) fractionated milk.

% Fat % H~O % FDM (fat dry matter) % NaCI pH (at 7 days) % Fat in Whey1 (w/volume correction) Yield2 (w/H 20 correction) kg cheese/kg milk solids kg cheese/kg fat

Control

Experimental (UF)

31.8 38.9 52.0 1.82 5.25

33.5 37.4 53.5 1.66 5.24

.47

.89

9,7

.82 2.53

10.2 1.O0 2.46

1Fat concentration was adjusted to achieve equivalency so that percentages are based upon the normal volume of whey from cheesemaking. 2Yield corrected for moisture is based upon following formula: kg Cheese × 100/(Original Weight of Skim Milk Before UF Fractionation + Weight of Cream). Journal of Dairy Science Vol. 66, No. 3, 1983

T A B L E 3. S u m m a r y o f m e a n s c o r e s f o r t h e d e s c r i p t i v e s e n s o r y a n a l y s i s o f C o l b y cheese. Sample attributes Samples

Cheese color I

Acidity 2

Bitterness 3

Cheese flavor 4

Off-flavor intensity 5

Firmness 6

Mealiness 7

P reference8

Mean scores 9 UW-Dairy Cheddar Cheese Commercial Colby Experimental Trial 1 Experimental Trial 2 Statistical Analysis F L S D ( a t 5%)

c~ 3.33 a 5.07 b

3.69 a 2.63 b

3.55 a 2.71 b

4.15 a 3.27 b

3.34 a 2.29 b

4.03 a 3.65bq

3.67 a 3.05 a

3.82 a 3.87 a

2.41 c

4.62 c

3.99 a

4.47 a

3.05 a

2.34 c

3-38 a

3.52a

4.18 d

2.79 b

2.84 b

3.27 b

2 . 8 1 ab

5.25 d

4.76 b

3.21 a

S

S

S

S

S

S

S

NS ....

.56

.60

.64

.56

1 Scale: 1 = m o t t l e d ; 7 = u n i f o r m .

.68

.43

.69

01 o~ ©

,q

,q 0~

2Scale: 1 = not detectable; 7 = strong. 3Scale: 1 = n o t d e t e c t a b l e ; 7 = s t r o n g . 4 Scale: 1 = i m p e r c e p t i b l e , l a c k i n g ; 7 = e x t r e m e l y p r o n o u n c e d . ~7

SScale: 1 = n o n e ; 7 = p r o n o u n c e d . 6 Scale: 1 = v e r y s o f t , v e r y e a s y t o p e n e t r a t e ; 7 = v e r y f i r m , v e r y h a r d t o p e n e t r a t e .

e~ ~°

7Scale: 1 = smooth; 7 = very mealy. 8 Scale: 1 = dislike v e r y m u c h ; 7 = like v e r y m u c h .

< O O, O,

Z .o t.m

00 t~

9n=27. S = S i g n i f i c a n t a t 5%; N S = n o t s i g n i f i c a n t . a ' b M e a n s c o r e s in s a m e c o l u m n w i t h s a m e s u p e r s c r i p t are n o t s i g n i f i c a n t l y d i f f e r e n t a t 5%.

Z7

F

420

BUSH ET AL.

and s o m e limitations of ultrafihration of milk for cheese manufacturing. Control of pH in washed-curd varieties such as Colby cheese, w i t h o u t the traditional curd washing procedure, appears feasible. The higher buffering capacity of milk and curd m a d e f r o m U F - f r a c t i o n a t e d milk plus the slightly l o w e r lactose apparently c o m p e n s a t e d for lack of lactose removal f r o m curd by washing. Additional lactose removal by diafihration or washing curd with small a m o u n t s of water may be necessary with brick cheese. Characteristics of Colby cheese m a d e f r o m UF-fractionated milk were reasonably close to commercial cheeses. The undesirable physical characteristics could be i m p r o v e d by appropriate choice o f m i l k - c l o t t i n g a n d p r o t e o l y t i c enzymes. Fat and curd-fine losses appear to be a m a j o r limitation of m a n u f a c t u r i n g cheese from UF-fractionated milk in conventional equipm e n t as indicated in this study and (9). Losses are significant w h e n m i l k is c o n c e n t r a t e d t w o - f o l d or m o r e which is a feasible degree of r e t e n t a t e c o n c e n t r a t i o n for on-farm U F systems with the permeate being fed back to the cows (8, 10, 19,

20). Losses of cheese yield m a y be o v e r c o m e by designing e q u i p m e n t to handle the curd f r o m U F - f r a c t i o n a t e d m i l k or less c o n c e n t r a t i o n might be used. The latter approach would reduce e c o n o m i c advantages of on-farm U F arising f r o m lower milk transportation costs and thermal energy for milk pasteurization, cooking of curd, and c o n c e n t r a t i o n and drying of whey. Reducing the milk v o l u m e by one-half on the farm still m i g h t be d o n e if water is added to the c o n c e n t r a t e after pasteurization in the cheese plant. The water could be treated to destroy microbial c o n t a m i n a n t s as in manufacturing of cottage cheese curd. Savings on pasteurization and transportation would be maintained, but energy savings on w h e y processing w o u l d n o t be as substantial if milk was diluted after pasteurization. ACKNOWLEDGMENTS

This research was s u p p o r t e d by the College of Agricultural and Life Sciences, Walter V. Price Cheese Research Institute, and the F o o d Engineering Pilot Plant. The authors wish to thank R o m i c o m Inc., Woburn, MA, for use of the u h r a f i h r a t i o n e q u i p m e n t , R. L. Bradley, R. C. Lindsay, and M. E. J o h n s o n for their Journal of Dairy Science Vol. 66, No. 3, 1983

assistance in cheese grading and Pat Cardiff and Carolyn Radeke for their aid in sample analysis. REFERENCES

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CHEESE FROM ULTRAFILTERED MILK

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