- Email: [email protected]
Fat Degradation in Cheddar Cheese Made from Pasteurized Milk, Without and With Added Lipase1,2
FAT DEGRADATION IN CHEDDAR CHEESE MADE FROM PASTEURIZED MILK, WITHOUT AND W I T H A D D E D L I P A S E 1'~ F. J. BABEL AND B. W. HAMMEI~ Iowa d gricuZtural Experiment Station, Ames, Iowa
The factors influencing flavor development in cheddar cheese have been extensively investigated, with the early studies largely involving the relationship of protein degradation to flavor production. Recently, the Iowa A g r i c u l t u r a l E x p e r i m e n t Station has been investigating the relationship of f a t degradation to flavor development (2, 3). As early as 1891, V a n Slyke (6) stated t h a t the chemical changes involved in the ripening of cheddar cheese were p r i m a r i l y a decompositiorL of the fats with the f o r m a t i o n of free f a t t y acids. These changes were said to occur m a i n l y a f t e r the earlier stages of ripening. Suzuki, H a s t i n g s a n d H a r t (5) concluded f r o m their studies t h a t the f a t was the m a i n source of the higher f a t t y acids present in cheddar cheese. E n z y m e s or organisms contained in the cheese were t h o u g h t to be capable of hydrolyzing glycerides. The authors stated that f u r t h e r experiments were necessary to show whether this action was due to ]ipases inherent in the milk or to living organisms. Lane and H a m m e r (2) f o u n d t h a t the f a t acidities of cheese m a d e f r o m r a w milk were slightly higher t h a n those of cheese made f r o m pasteurized milk when the cheese were fresh and also increased more d u r i n g ripening. W h e n extracted with ether and the ether evaporated, steam distillates f r o m aged cheese yielded oily residues having an odor suggestive of higher volatile f a t t y acids. These investigators (3) also made cheese f r o m r a w homogenized cream mixed with skim milk ( r a w or pasteurized). The cheese comm o n l y developed a rancid flavor early in the ripening, but the r a n c i d i t y tended to disappear as ripening progressed, and eventually the cheese were not rancid and were more satisfactorjT in flavor t h a n cheese made f r o m pasteurized milk or f r o m pasteurized homogenized cream mixed with pasteurized skim~milk. I n some cases the cheese were ~more satisfactory in flavor t h a n cheese made f r o m raw milk. Addition of p a n c r e a t i n to pasteurized milk resulted in a rancid a n d bitter flavor in the cheese b u t addition of desiccated m a m m a r y tissue commonly had a desirable effect on the cheese flavor. The m a m m a r y tissue increased the f a t acidities of the cheese a n d also the soluble nitrogen contents. Receivea for publication September 16, 1944. 1 Journal Paper J-1232 of the Iowa Agrlcu]tural Experiment Station, Ames, Iowa. Project 652. 2 The studies were financed in part through a grant from Chr. ttansen's Laboratory, Inc, Milwaukee, Wisconsin. 201
202
I.. J. BABEL A N D B. W . H A M M E R
~VIET~IODS
The milk used for cheese m a n u f a c t u r e was mixed herd milk with a f a t content of 3.8 to 4.0 per cent. I t was pasteurized at 143 ° F. for 30 minutes in a s p r a y - v a t pasteurizer. F i f t y gallons of milk was used for each trial. I n all trials the method of m a n u f a c t u r e followed was essentially t h a t of Wilson (7). The cheese were ripened at 50 ° F. The method used for determining the p H of the cheese was t h a t described b y Sanders (4) for the determination of p H of semi-plastic solids. The cheese f a t was obtained b y subjecting a m i x t u r e of finely grated cheese and sand to relatively high pressures in a hydraulic press (2). The f a t was filtered through p a p e r and titrated according to the method suggested by Breazeale and Bird (1). RESULTS
Fat degradatiou ,in control cheese from pasteurized milk. The f a t acidities of 21 lots of cheese made f r o m pasteurized milk are presented in table 1. TABLE 1
Fat acidities of cheddar cheese made fro~r~ paste~rized mil~'. No Zipase added Date of manufacture 12-18-42 12-22--42 12-26-42 12-29-42 1 - 7-43 1-11-43 1-18-43
Acid No. of f a t (ml. N / 2 0 K O I I per 10 gin. f a t ) 3 days
I month
2 months
3 months
6 months
9 nmnths
1.46
1.88 1.63 1.53 1.52 1.67 1.75 1.88 1.41 1.59 1.74 1.50 1.47 1.61 1.48 1.75 1.71 2.32 2.04 ].82 1.83 1.41 1.69
2.09 1.69 2.03 1.60 1.79 1.93 2.29 1.98 1.90 2.12 2.01
2.10 1.74 2.22 1.91 2.29 2.02 2.49 2.25 2.20 2.13 2.39 2.20 2.34 2.00 2.45 2.34 2.64 2.59 2.53 2.24 1.75 2.23
2.85 2.75 3.20 3.40 3.72 3.27 4.38 3.22 3.29 2.74 2.79 2.98 3.57 2.40 3.51 2.88 3.12 3.02 2.98 2.51 2.34 3.09
3.46 3.52 3.92 4.11 4.73 4.40 5.29 4.06 4.37 3.54 3.13 3.64 5.62 3.01 5.31 3.61
1.50
1.42 1.48
1-25-43 2- 1-43 2 - 8-43 2-15-43 2-22-43 3 - 1-43 3 - 8-43 3-22-43 3-29-43 4- 5-43 4-12-43 4-19-43 4-26-43 5- 4-43 Average
1.51 1.44 1.50 1.52 1.45 1.41 1.40 1.46
2.05
.88 1.67 2.20 2.04 2.45 2.36 2.21 2.06 1.52 1.99
3.95 3.61 3.65 2.91 3.08 3.95
Only slight variations were observed in the original acidities of the eleven lots of cheese on which determinations were made 3 days a f t e r m a n u f a c t u r e ; the values r a n g e d f r o m 1.40 to 1.52 and averaged 1.46. The f a t acidities increased during ripening at a more or less regul, ar rate. On the basis of
FAT DEGRADATION IN Ol=IEDDAR CHEESE
203
av erag es , t h e y i n c r e a s e d the first m o n t h b y 0.23, t h e second m o n t h b y 0.30 a n d t h e t h i r d m o n t h by 0.24; f r o m t h e t h i r d to t h e si x t h m o n t h t h e y inc r e a s e d b y 0.86 ( e q u a l to 0.287 p e r m o n t h ) a n d f r o m t h e s i x t h to t h e n i n t h m o n t h b y 0.86 ( e q u a l to 0.287 p e r m o n t h ) . W i t h some of the cheese t h e f a t a c i d i t i e s i n c r e a s e d m o r e r a p i d l y t h a n w i t h others. T h e i n c r e a s e s w e r e not c o r r e l a t e d w i t h th e p.It of the cheese, t h e a c i d i t y of t h e w h e y a t m i l l i n g or the m o i s t u r e or f a t c o n t e n t of th e cheese. I n t h r e e t r i a l s r e n n e t e x t r a c t a n d r e n n e t p o w d e r w e r e c o m p a r e d f r o m the s t a n d p o i n t s of q u a l i t y of cheese a n d f a t d e g r a d a t i o n in it. No s i g n i f i c a n t TABLE 2 Fat acidities and degree of rancidity of cheddar cheese made from pasteurized milk. Lipase added in form of rennet paste Per 1000 lbs. milk Date of manufacture 1-25-43 1-11-43 3- 8-43 12-22-42 12-18-42 1-25-43 3- 1-43 1-18-43 1-18-43 1-11-43 12-26-42 12-29-42 12-26-42 12-29-42 12-18-42 3- 8-43 12-22-42 3- 1-43 1- 7-43
Acid No. of fat (M1. N / 2 0 K O t t p e r 10 gm. fat)
Flavor of cheese
Gm. rennet paste
MI. rennet extract
3months
6months
3months
6months
13 13 40 40 40 40 40 40 40 40 50 50 50 50 80 80 80 80 225
85 85 74 74 74 74 74 74 74 74 70 70 70 70 58 58 58 58 '0
2.40 3.14 2.64 2.35 2.51 2.83 3.40 3.81 3.73 3.51 3.26 3.52 3.90 4.03 3.29 3.71 2.99 5.71 8.10
3.89 5.82 3.64 3.73 4.50 4.50 4.76 6.55 6.70 6.96 5.21 6.08 6.23 7.23 3.85 4.38 5.85 8.56 15.25
Not rancid Not rancid Not rancid :Not rancid Not rancid Not rancid Not rancid V. sl. rancid V. sl. rancid S1. rancid S1. rancid S1. rancid Not rancid Not rancid S1. rancid S]. rancid Rancid Rancid V. rancid
Not rancid Not rancid Not rancid Not rancid Not rancid Not rancid :Not rancid Not rancid Not rancid St. rancid S1. rancid S1. rancid S1. rancid S1. rancid Not rancid S1. rancid Not rancid Rancid V. rancid
d i f f e r e n c e i n f l a v o r w a s e v i d e n t , a n d the f a t a c i d i t i e s i n c r e a s e d a t a p p r o x i m a t e l y t h e same r a te . I n a n a t t e m p t to e x p l a i n t h e cause of f a t d e g r a d a t i o n in t h e cheese, p u r i fied b u t t e r f a t w a s p r e p a r e d f r o m fresh, p a s t e u r i z e d sw eet cream. T h e sweet c r e a m was p a s t e u r i z e d a t 145 ° F . f o r 30 m i n u t e s , cooled a n d c h u r n e d . The r e s u l t i n g b u t t e r was h e l d at 104 ° F . u n t i l the b u t t e r f a t a n d s e r m u h a d separated. T h e b u t t e r f a t was t h e n f i l t e r e d t h r o u g h p a p e r a n d p o r t i o n s h e l d in e r l e n m e y e r flasks at t h e cheese r i p e n i n g t e m p e r a t u r e (50 ° F . ) . T h e r e was no s i g n i f i c a n t i n c r e a s e in t h e f a t a c i d i t y , e v e n a f t e r h o l d i n g f o r a p p r o x i m a t e l y 8 m o n t h s ; d u r i n g this p e r i o d the f a t a c i d i t y i n c r e a s e d f r o m 1.20 to 1.25. F a t degradation in cheese made w i t h r e n n e t paste. T a b l e 2 shows t h e f a t
204
F. J .
B A B E L A N D B. W'. H A M M E R
aeiflities and degrees of rancidity of 19 lots of cheddar cheese m a d e f r o m pasteurized milk with various amounts of lipase added in the f o r m of rennet paste. I n the m a n u f a c t u r e of the cheese, 225 g r a m s of paste was considered equivalent to 3 ounces of rennet extract ; and, as the amount of rennet paste was increased, the amount of rennet extract was decreased in proportion so t h a t the coagulating power would remain the same. The f a t acidities of the two lots of cheese m a d e with rennet paste added at the rate of 13 grams per 1,000 pounds of milk showed increases over the control cheese (table 1), the increase being considerably greater in one case t h a n in the other• The cheese were not rancid at a n y time during the ripening and at 3 months, 6 months and 9 months were considered to be slightly better in flavor t h a n the cheese made without added lipase. The small a m o u n t of rennet paste increased the cheese flavor and tended to mask the slightly sour flavor evident in the control cheese. W h e n rennet paste was added at the rate of 40 grams per 1,000 pounds of milk, the f a t acidities did not increase in p r o p o r t i o n to the increases obtained when 13 grams of the paste was added• There was considerable variation in the increases with the different trials and with two of the eight lots of cheese the f a t acidities at 6 months were slightly lower t h a n in one of the trials with 13 g r a m s of paste. Each of the eight lots of cheese in the series showed some rancid flavor during the first 3 months, although at 3 months five of them were not r a n c i d ; at 6 months only one lot was slightly rancid and it had the highest f a t acidity. A t 6 months seven of the eight lots of cheese were considered to have a better flavor t h a n the corresponding control ~heese and one lot was considered equal in flavor to the control cheese. F o u r lots of cheese were made with 50 g r a m s of rennet paste per 1,000 pounds of milk. A slightly higher average f a t acidity was obtained than with 40 grams of paste. However, with the 50 g r a m additions, all f o u r lots of cheese were slightly rancid a f t e r 6 months. The slight rancidity was not considered definitely objectionable by some of the judges while it was by others. F o u r lots of cheese were made with 80 g r a m s of rennet paste per 1,000 pounds of milk. The f a t acidities a f t e r 6 months showed a r a t h e r wide variation (3.85 to 8.56). A t 3 months all of the lots showed some rancidity but at 6 months only two lots were rancid. A t 6 months two lots in the series were considered to have a better flavor t h a n the corresponding control cheese and two lots were considered inferior in flavor. Three lots of cheese were made with rennet paste as the sole coagulating agent (225 g r a m s per 1,000 pounds of milk) b u t the f a t acidities were determined on only one of them. The f a t acidity increased r a t h e r r a p i d l y and a value of 15.25 was obtained at 6 months. All three lots of cheese in the series were v e r y rancid throughout the entire ripening period (9 months).
FAT DEGRADATION
IN C H E D D A R
205
CHEESE
The variations within a series could not be correlated with the p i t of the cheese. Also, there was no correlation between the amount of rennet paste used and the increase in p H of the cheese on holding. Fat degradation in cheese made w.ith mulberry juice. Results of 12 trials in which m u l b e r r y juice was usad as a source of lipase are presented in table 3. The m u l b e r r y juice was obtained f r o m frozen berries by grinding and pressing and was usually p r e p a r e d only a short time before it was to be used. I t was noted t h a t the lipolytic activity of m u l b e r r y juice decreased r a p i d l y if a v e r y acid juice was allowed to s t a n d ; neutralization of the acidity helped to preserve the activity. The m u l b e r r y juice was added in amounts r a n g i n g f r o m 50 to 200 ml. per 1,000 pounds of milk and in each trial the normal amount of rennet extract was used. TABLE 3
Fat acidities and degree of rancidity of cheddar cheese made from pasteurized milk. Lipase added in form of mulberry juice AcidNo. of f a t Date of
manufacture
~{I. mulberry juice per 1000 lbs. milk
(MI. N/20 K O t I 3 months
2 - 1-43 2 - 8-43 3-22-43 3-29-43 2-22-43 2-22-43 3-29-43 2 - 8-43 2 - 1-43 2-15-43 2-15-43 3-22--43
50 50 65 80 150 150 160 175 200 200 200 200
(Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot
108) 103) 110) 110) 110) 110) 110) 103) 108) 110) 110) 110)
Flavor of cheese
per 10 gm. f a t )
2.25 3.69 9.12 8.12 13.75 16.49 9.62 6.07 3.23 12.72 14.87 15.33
6 months
3months
3.21 5.72 15.77 i3.20 22.54 26.66 13.71 10.07 5.36 21.72 24.87 25.26
Not rancid Not rancid Rancid Rancid Rancid Rancid Rancid S1. rancid S1. rancid S1. rancid S1. rancid Rancid
I
6months Not rancid Not rancid Rancid Rancid Rancid Very rancid Very rancid SL rancid Not rancid S1. rancid l~ancid Rancid
W i t h the smallest amount of juice (50 ml.), the f a t acidity in one trial was no greater t h a n that of the control cheese, while in the other trial it was only slightly increased. Different lots of mulberries were used in the two trials. The cheese were not rancid during the ripening and were v e r y similar in flavor to the control cheese. The cheese made with larger amounts of m u l b e r r y juice, f r o m 65 to 200 ml. per 1,000 pounds of milk, showed appreciable increases in f a t acidities over the control cheese and all were rancid at some stage of the ripening. A t 6 months only one of the ten lots was graded as not rancid. W i t h this lot the f a t acidity was only slightly higher t h a n with the control cheese. Different lots of mulberries showed considerable variation in their ability to hydrolyze cheese fat. I n general, the white v a r i e t y of berries was more active than the red variety. Lots 103 and 108 were red berries a n d were r a t h e r inactive, whereas lot 110 was white berries and was v e r y active. The
206
~'. J . BABEL A N D B. W. t t A M M E R
cheese made with additions of m u l b e r r y juice greater than 50 ml. per 1,000 pounds of milk sometimes were considered superior in flavor to the control cheese during the early stages of ripening ( a p p r o x i m a t e l y 1 m o n t h ) . However, a f t e r 3 months the cheese were. graded as rancid or unclean and were inferior to the control cheese. The rancid and unclean flavors were more pronounced a f t e r 6 months. The rancid flavor obtained with addition of m u l b e r r y juice did not a p p e a r to decrease in intensity as was the case with certain of the lots of cheese made with rennet paste. Manufacture of process cheese. Process cheese was p r e p a r e d f r o m various lots of cheese containing added lipase. Usually, 25 per cent of aged cheese containing added lipase was used in each batch. The aged cheese showed ~arying degrees of rancidity. The resulting process cheese was not rancid and was considered to have more cheese flavor than process cheese made b y using 25 per cent of aged control cheese. DISCUSSION
The results presented indicate a definite increase in the f a t acidity of cheddar cheese made from pasteurized milk without addition of lipase. The average increase f r o m month to m o n t h was quite u n i f o r m and there was no evidence of.an acceleration in the f a t breakdown. The increase in f a t acidity could be due to the production of lipase by certain organisms in the, cheese or to the solution in the f a t of certain acids produced by organisms. I n the trials with rennet paste, the results suggest that some f a t hydrolysis in pasteurized milk cheese is beneficial f r o m the standpoint of production of cheddar cheese flavor. Variations were encountered in the fat acidities of cheese made with the same amounts of rennet paste. I f larger lots of cheese had been made, there m i g h t have been more uniformity. Some method of standardization would a p p e a r desirable so that the degree of f a t hydrolysis can be controlled. A considerable difference was noted in the cheese made with rennet paste as a source of lipase and that made with added m u l b e r r y juice. The r a n c i d i t y developed in cheese made with rennet paste was not as objectionable as the r a n c i d i t y produced b y the m u l b e r r y juice. The results suga)est some selective f a t hydrolysis. A slight rancidity d u r i n g the early p a r t of the ripening in cheese made with rennet paste usually disappeared later, while this commonly was not the case with cheese made with m u l b e r r y juice. These results are in general agreement with the suggestion of L a n e and t t a m m e r (3) that lipase f r o m certain sources is not suitable for use in cheddar cheese. Different lots of m u l b e r r y juice showed significant differences in their ability to hydrolyze cheese f a t ; juice f r o m white berries being more lipolytic t h a n juice f r o m red berries. Increased amounts of m u l b e r r y juice did not always show a n increased amount of f a t hydrolysis, even when the same lots of berries were used.
FAT DEGRADATION IN CHEDDAR CHEESE
207
The relation of f a t hydrolysis to flavor in cheddar cheese is f u r t h e r emphasized when process cheese is made f r o m a blend containing some cheese exhibiting f a t hydrolysis. The slight rancidity, a p p a r e n t in certain of the aged cheese showing rather extensive f a t hydrolysis, is diluted when blended with y o u n g cheese so t h a t the resulting process cheese does not have a rancid flavor. I t is also possible that some of the free acids responsible f o r the r a n c i d i t y m a y be volatilized d u r i n g the processing operation. SUMMARY
The f a t acidities of cheddar cheese made f r o m pasteurized milk without added lipase were v e r y similar when the cheese were 3 days old. Increases occurred t h r o u g h o u t the ripening period. The increases were not u n i f o r m with the different lots of cheese a n d could not be correlated with the p i t of the cheese, the acidity of the whey at milling, or the moisture or f a t content of the cheese. The f a t acidities of cheese m a d e with rennet extract and with rennet powder increased at a p p r o x i m a t e l y the same rate. Purified butterfat, obtained f r o m pasteurized sweet cream and held at the cheese ripening t e m p e r a t u r e (50 ° F . ) , did not increase significantly in acidity. Addition of a small amount of r e n n e t paste (13 to 40 g r a m s per 1,000 pounds milk) resulted in an increase in f a t acidity of the cheese. Some of the cheese showed v a r y i n g degrees of rancidity early in the ripening, b u t this r a n c i d i t y disappeared or n e a r l y disappeared before the cheese were 6 months old. The cheese (made with rennet paste) that were not rancid were superior in flavor to the control cheese. The use of a small a m o u n t of rennet paste tended to mask the sour, acid flavor f r e q u e n t l y encountered in the control cheese. Addition of a larger a m o u n t of rennet paste (50 to 225 g r a m s per 1,000 pounds of milk) resulted in a significant increase in f a t acidity of the cheese. All of the cheese showed r a n c i d i t y at some time during the ripening and certain lots were rancid when the cheese were 6 months old. The addition of m u l b e r r y juice to pasteurized milk did not improve the tta~or of the resulting cheese. Small amounts had little effect on the flavor while larger amounts resulted in raneid and unclean flavors. The use of a certain amount of aged cheese showing definite f a t hydrolysis was benefieial f r o m the standpoint of flavor of process cheese. Process cheese containing some aged cheese made with addition of rennet paste had more flavor t h a n process cheese m a d e with an equivalent amount of aged control cheese. REFERENCES
(1) ]3REAZEALE,D. F., AND BIRD/ E . W .
A S t u d y of M e t h o d s f o r the D e t e r m i n a t i o n o f A c i d i t y in ]3utter F a t . JOVR. DAmY ScI., 21: 335-344. 1938. (2) :LANE, C. ]3., AND }IAI~SIEI~, ]3. W. S t u d i e s on the F a t of Cheddar Cheese. I o w a S t a t e Col. J o u r . Sci., 13: 149-155. 1939.
208
F.J.
BABEL AND B. W. HA~£MER
(3) LANE, C. B., AND HAMMER, B . W . Bacteriology of Cheese. VI. Relationship of P a t Hydrolysis to the Ripening of Cheddar Cheese. Iowa Agr. Expt. Sta., Res. Bul. 291. 1941. (4) SANDERS, GEORGE P. A Simplified Quinhydrone Electrode. Application in Determining the H-ion Concentration of Liquids and Semiplasti¢ Solids. Indus. and Engin. Chem., Analyt. Ed., 10: 274-275. 1938. (5) SuzuKI, S. K., HASTINGS, E. G., AND HART, E . B . The Production of Volatile P a t t y Acids and Esters in Cheddar Cheese and Their Relation to the Development of Flavor. Wis. Agr. Expt. Sta., Res. Bul. 11. 1910. (6) VAN SL'YKE,L. a. Investigation of Cheese. Experiments in the Manufacture of Cheese. Influence of Composition of Milk on Composition and Yield of Cheese. A Study of the Process of Ripening of Cheese. N . Y . (Geneva) Agr. Expt. Sta., Bul. 37. 1891. (7) WILSON, H. L. Manufacture of American Cheese from Pasteurized Milk. Natl. Butter and Cheese Jour., 33 (2) : 18, 20, 22, 24-28. 1942.
The factors influencing flavor development in cheddar cheese have been extensively investigated, with the early studies largely involving the relationship of protein degradation to flavor production. Recently, the Iowa A g r i c u l t u r a l E x p e r i m e n t Station has been investigating the relationship of f a t degradation to flavor development (2, 3). As early as 1891, V a n Slyke (6) stated t h a t the chemical changes involved in the ripening of cheddar cheese were p r i m a r i l y a decompositiorL of the fats with the f o r m a t i o n of free f a t t y acids. These changes were said to occur m a i n l y a f t e r the earlier stages of ripening. Suzuki, H a s t i n g s a n d H a r t (5) concluded f r o m their studies t h a t the f a t was the m a i n source of the higher f a t t y acids present in cheddar cheese. E n z y m e s or organisms contained in the cheese were t h o u g h t to be capable of hydrolyzing glycerides. The authors stated that f u r t h e r experiments were necessary to show whether this action was due to ]ipases inherent in the milk or to living organisms. Lane and H a m m e r (2) f o u n d t h a t the f a t acidities of cheese m a d e f r o m r a w milk were slightly higher t h a n those of cheese made f r o m pasteurized milk when the cheese were fresh and also increased more d u r i n g ripening. W h e n extracted with ether and the ether evaporated, steam distillates f r o m aged cheese yielded oily residues having an odor suggestive of higher volatile f a t t y acids. These investigators (3) also made cheese f r o m r a w homogenized cream mixed with skim milk ( r a w or pasteurized). The cheese comm o n l y developed a rancid flavor early in the ripening, but the r a n c i d i t y tended to disappear as ripening progressed, and eventually the cheese were not rancid and were more satisfactorjT in flavor t h a n cheese made f r o m pasteurized milk or f r o m pasteurized homogenized cream mixed with pasteurized skim~milk. I n some cases the cheese were ~more satisfactory in flavor t h a n cheese made f r o m raw milk. Addition of p a n c r e a t i n to pasteurized milk resulted in a rancid a n d bitter flavor in the cheese b u t addition of desiccated m a m m a r y tissue commonly had a desirable effect on the cheese flavor. The m a m m a r y tissue increased the f a t acidities of the cheese a n d also the soluble nitrogen contents. Receivea for publication September 16, 1944. 1 Journal Paper J-1232 of the Iowa Agrlcu]tural Experiment Station, Ames, Iowa. Project 652. 2 The studies were financed in part through a grant from Chr. ttansen's Laboratory, Inc, Milwaukee, Wisconsin. 201
202
I.. J. BABEL A N D B. W . H A M M E R
~VIET~IODS
The milk used for cheese m a n u f a c t u r e was mixed herd milk with a f a t content of 3.8 to 4.0 per cent. I t was pasteurized at 143 ° F. for 30 minutes in a s p r a y - v a t pasteurizer. F i f t y gallons of milk was used for each trial. I n all trials the method of m a n u f a c t u r e followed was essentially t h a t of Wilson (7). The cheese were ripened at 50 ° F. The method used for determining the p H of the cheese was t h a t described b y Sanders (4) for the determination of p H of semi-plastic solids. The cheese f a t was obtained b y subjecting a m i x t u r e of finely grated cheese and sand to relatively high pressures in a hydraulic press (2). The f a t was filtered through p a p e r and titrated according to the method suggested by Breazeale and Bird (1). RESULTS
Fat degradatiou ,in control cheese from pasteurized milk. The f a t acidities of 21 lots of cheese made f r o m pasteurized milk are presented in table 1. TABLE 1
Fat acidities of cheddar cheese made fro~r~ paste~rized mil~'. No Zipase added Date of manufacture 12-18-42 12-22--42 12-26-42 12-29-42 1 - 7-43 1-11-43 1-18-43
Acid No. of f a t (ml. N / 2 0 K O I I per 10 gin. f a t ) 3 days
I month
2 months
3 months
6 months
9 nmnths
1.46
1.88 1.63 1.53 1.52 1.67 1.75 1.88 1.41 1.59 1.74 1.50 1.47 1.61 1.48 1.75 1.71 2.32 2.04 ].82 1.83 1.41 1.69
2.09 1.69 2.03 1.60 1.79 1.93 2.29 1.98 1.90 2.12 2.01
2.10 1.74 2.22 1.91 2.29 2.02 2.49 2.25 2.20 2.13 2.39 2.20 2.34 2.00 2.45 2.34 2.64 2.59 2.53 2.24 1.75 2.23
2.85 2.75 3.20 3.40 3.72 3.27 4.38 3.22 3.29 2.74 2.79 2.98 3.57 2.40 3.51 2.88 3.12 3.02 2.98 2.51 2.34 3.09
3.46 3.52 3.92 4.11 4.73 4.40 5.29 4.06 4.37 3.54 3.13 3.64 5.62 3.01 5.31 3.61
1.50
1.42 1.48
1-25-43 2- 1-43 2 - 8-43 2-15-43 2-22-43 3 - 1-43 3 - 8-43 3-22-43 3-29-43 4- 5-43 4-12-43 4-19-43 4-26-43 5- 4-43 Average
1.51 1.44 1.50 1.52 1.45 1.41 1.40 1.46
2.05
.88 1.67 2.20 2.04 2.45 2.36 2.21 2.06 1.52 1.99
3.95 3.61 3.65 2.91 3.08 3.95
Only slight variations were observed in the original acidities of the eleven lots of cheese on which determinations were made 3 days a f t e r m a n u f a c t u r e ; the values r a n g e d f r o m 1.40 to 1.52 and averaged 1.46. The f a t acidities increased during ripening at a more or less regul, ar rate. On the basis of
FAT DEGRADATION IN Ol=IEDDAR CHEESE
203
av erag es , t h e y i n c r e a s e d the first m o n t h b y 0.23, t h e second m o n t h b y 0.30 a n d t h e t h i r d m o n t h by 0.24; f r o m t h e t h i r d to t h e si x t h m o n t h t h e y inc r e a s e d b y 0.86 ( e q u a l to 0.287 p e r m o n t h ) a n d f r o m t h e s i x t h to t h e n i n t h m o n t h b y 0.86 ( e q u a l to 0.287 p e r m o n t h ) . W i t h some of the cheese t h e f a t a c i d i t i e s i n c r e a s e d m o r e r a p i d l y t h a n w i t h others. T h e i n c r e a s e s w e r e not c o r r e l a t e d w i t h th e p.It of the cheese, t h e a c i d i t y of t h e w h e y a t m i l l i n g or the m o i s t u r e or f a t c o n t e n t of th e cheese. I n t h r e e t r i a l s r e n n e t e x t r a c t a n d r e n n e t p o w d e r w e r e c o m p a r e d f r o m the s t a n d p o i n t s of q u a l i t y of cheese a n d f a t d e g r a d a t i o n in it. No s i g n i f i c a n t TABLE 2 Fat acidities and degree of rancidity of cheddar cheese made from pasteurized milk. Lipase added in form of rennet paste Per 1000 lbs. milk Date of manufacture 1-25-43 1-11-43 3- 8-43 12-22-42 12-18-42 1-25-43 3- 1-43 1-18-43 1-18-43 1-11-43 12-26-42 12-29-42 12-26-42 12-29-42 12-18-42 3- 8-43 12-22-42 3- 1-43 1- 7-43
Acid No. of fat (M1. N / 2 0 K O t t p e r 10 gm. fat)
Flavor of cheese
Gm. rennet paste
MI. rennet extract
3months
6months
3months
6months
13 13 40 40 40 40 40 40 40 40 50 50 50 50 80 80 80 80 225
85 85 74 74 74 74 74 74 74 74 70 70 70 70 58 58 58 58 '0
2.40 3.14 2.64 2.35 2.51 2.83 3.40 3.81 3.73 3.51 3.26 3.52 3.90 4.03 3.29 3.71 2.99 5.71 8.10
3.89 5.82 3.64 3.73 4.50 4.50 4.76 6.55 6.70 6.96 5.21 6.08 6.23 7.23 3.85 4.38 5.85 8.56 15.25
Not rancid Not rancid Not rancid :Not rancid Not rancid Not rancid Not rancid V. sl. rancid V. sl. rancid S1. rancid S1. rancid S1. rancid Not rancid Not rancid S1. rancid S]. rancid Rancid Rancid V. rancid
Not rancid Not rancid Not rancid Not rancid Not rancid Not rancid :Not rancid Not rancid Not rancid St. rancid S1. rancid S1. rancid S1. rancid S1. rancid Not rancid S1. rancid Not rancid Rancid V. rancid
d i f f e r e n c e i n f l a v o r w a s e v i d e n t , a n d the f a t a c i d i t i e s i n c r e a s e d a t a p p r o x i m a t e l y t h e same r a te . I n a n a t t e m p t to e x p l a i n t h e cause of f a t d e g r a d a t i o n in t h e cheese, p u r i fied b u t t e r f a t w a s p r e p a r e d f r o m fresh, p a s t e u r i z e d sw eet cream. T h e sweet c r e a m was p a s t e u r i z e d a t 145 ° F . f o r 30 m i n u t e s , cooled a n d c h u r n e d . The r e s u l t i n g b u t t e r was h e l d at 104 ° F . u n t i l the b u t t e r f a t a n d s e r m u h a d separated. T h e b u t t e r f a t was t h e n f i l t e r e d t h r o u g h p a p e r a n d p o r t i o n s h e l d in e r l e n m e y e r flasks at t h e cheese r i p e n i n g t e m p e r a t u r e (50 ° F . ) . T h e r e was no s i g n i f i c a n t i n c r e a s e in t h e f a t a c i d i t y , e v e n a f t e r h o l d i n g f o r a p p r o x i m a t e l y 8 m o n t h s ; d u r i n g this p e r i o d the f a t a c i d i t y i n c r e a s e d f r o m 1.20 to 1.25. F a t degradation in cheese made w i t h r e n n e t paste. T a b l e 2 shows t h e f a t
204
F. J .
B A B E L A N D B. W'. H A M M E R
aeiflities and degrees of rancidity of 19 lots of cheddar cheese m a d e f r o m pasteurized milk with various amounts of lipase added in the f o r m of rennet paste. I n the m a n u f a c t u r e of the cheese, 225 g r a m s of paste was considered equivalent to 3 ounces of rennet extract ; and, as the amount of rennet paste was increased, the amount of rennet extract was decreased in proportion so t h a t the coagulating power would remain the same. The f a t acidities of the two lots of cheese m a d e with rennet paste added at the rate of 13 grams per 1,000 pounds of milk showed increases over the control cheese (table 1), the increase being considerably greater in one case t h a n in the other• The cheese were not rancid at a n y time during the ripening and at 3 months, 6 months and 9 months were considered to be slightly better in flavor t h a n the cheese made without added lipase. The small a m o u n t of rennet paste increased the cheese flavor and tended to mask the slightly sour flavor evident in the control cheese. W h e n rennet paste was added at the rate of 40 grams per 1,000 pounds of milk, the f a t acidities did not increase in p r o p o r t i o n to the increases obtained when 13 grams of the paste was added• There was considerable variation in the increases with the different trials and with two of the eight lots of cheese the f a t acidities at 6 months were slightly lower t h a n in one of the trials with 13 g r a m s of paste. Each of the eight lots of cheese in the series showed some rancid flavor during the first 3 months, although at 3 months five of them were not r a n c i d ; at 6 months only one lot was slightly rancid and it had the highest f a t acidity. A t 6 months seven of the eight lots of cheese were considered to have a better flavor t h a n the corresponding control ~heese and one lot was considered equal in flavor to the control cheese. F o u r lots of cheese were made with 50 g r a m s of rennet paste per 1,000 pounds of milk. A slightly higher average f a t acidity was obtained than with 40 grams of paste. However, with the 50 g r a m additions, all f o u r lots of cheese were slightly rancid a f t e r 6 months. The slight rancidity was not considered definitely objectionable by some of the judges while it was by others. F o u r lots of cheese were made with 80 g r a m s of rennet paste per 1,000 pounds of milk. The f a t acidities a f t e r 6 months showed a r a t h e r wide variation (3.85 to 8.56). A t 3 months all of the lots showed some rancidity but at 6 months only two lots were rancid. A t 6 months two lots in the series were considered to have a better flavor t h a n the corresponding control cheese and two lots were considered inferior in flavor. Three lots of cheese were made with rennet paste as the sole coagulating agent (225 g r a m s per 1,000 pounds of milk) b u t the f a t acidities were determined on only one of them. The f a t acidity increased r a t h e r r a p i d l y and a value of 15.25 was obtained at 6 months. All three lots of cheese in the series were v e r y rancid throughout the entire ripening period (9 months).
FAT DEGRADATION
IN C H E D D A R
205
CHEESE
The variations within a series could not be correlated with the p i t of the cheese. Also, there was no correlation between the amount of rennet paste used and the increase in p H of the cheese on holding. Fat degradation in cheese made w.ith mulberry juice. Results of 12 trials in which m u l b e r r y juice was usad as a source of lipase are presented in table 3. The m u l b e r r y juice was obtained f r o m frozen berries by grinding and pressing and was usually p r e p a r e d only a short time before it was to be used. I t was noted t h a t the lipolytic activity of m u l b e r r y juice decreased r a p i d l y if a v e r y acid juice was allowed to s t a n d ; neutralization of the acidity helped to preserve the activity. The m u l b e r r y juice was added in amounts r a n g i n g f r o m 50 to 200 ml. per 1,000 pounds of milk and in each trial the normal amount of rennet extract was used. TABLE 3
Fat acidities and degree of rancidity of cheddar cheese made from pasteurized milk. Lipase added in form of mulberry juice AcidNo. of f a t Date of
manufacture
~{I. mulberry juice per 1000 lbs. milk
(MI. N/20 K O t I 3 months
2 - 1-43 2 - 8-43 3-22-43 3-29-43 2-22-43 2-22-43 3-29-43 2 - 8-43 2 - 1-43 2-15-43 2-15-43 3-22--43
50 50 65 80 150 150 160 175 200 200 200 200
(Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot (Lot
108) 103) 110) 110) 110) 110) 110) 103) 108) 110) 110) 110)
Flavor of cheese
per 10 gm. f a t )
2.25 3.69 9.12 8.12 13.75 16.49 9.62 6.07 3.23 12.72 14.87 15.33
6 months
3months
3.21 5.72 15.77 i3.20 22.54 26.66 13.71 10.07 5.36 21.72 24.87 25.26
Not rancid Not rancid Rancid Rancid Rancid Rancid Rancid S1. rancid S1. rancid S1. rancid S1. rancid Rancid
I
6months Not rancid Not rancid Rancid Rancid Rancid Very rancid Very rancid SL rancid Not rancid S1. rancid l~ancid Rancid
W i t h the smallest amount of juice (50 ml.), the f a t acidity in one trial was no greater t h a n that of the control cheese, while in the other trial it was only slightly increased. Different lots of mulberries were used in the two trials. The cheese were not rancid during the ripening and were v e r y similar in flavor to the control cheese. The cheese made with larger amounts of m u l b e r r y juice, f r o m 65 to 200 ml. per 1,000 pounds of milk, showed appreciable increases in f a t acidities over the control cheese and all were rancid at some stage of the ripening. A t 6 months only one of the ten lots was graded as not rancid. W i t h this lot the f a t acidity was only slightly higher t h a n with the control cheese. Different lots of mulberries showed considerable variation in their ability to hydrolyze cheese fat. I n general, the white v a r i e t y of berries was more active than the red variety. Lots 103 and 108 were red berries a n d were r a t h e r inactive, whereas lot 110 was white berries and was v e r y active. The
206
~'. J . BABEL A N D B. W. t t A M M E R
cheese made with additions of m u l b e r r y juice greater than 50 ml. per 1,000 pounds of milk sometimes were considered superior in flavor to the control cheese during the early stages of ripening ( a p p r o x i m a t e l y 1 m o n t h ) . However, a f t e r 3 months the cheese were. graded as rancid or unclean and were inferior to the control cheese. The rancid and unclean flavors were more pronounced a f t e r 6 months. The rancid flavor obtained with addition of m u l b e r r y juice did not a p p e a r to decrease in intensity as was the case with certain of the lots of cheese made with rennet paste. Manufacture of process cheese. Process cheese was p r e p a r e d f r o m various lots of cheese containing added lipase. Usually, 25 per cent of aged cheese containing added lipase was used in each batch. The aged cheese showed ~arying degrees of rancidity. The resulting process cheese was not rancid and was considered to have more cheese flavor than process cheese made b y using 25 per cent of aged control cheese. DISCUSSION
The results presented indicate a definite increase in the f a t acidity of cheddar cheese made from pasteurized milk without addition of lipase. The average increase f r o m month to m o n t h was quite u n i f o r m and there was no evidence of.an acceleration in the f a t breakdown. The increase in f a t acidity could be due to the production of lipase by certain organisms in the, cheese or to the solution in the f a t of certain acids produced by organisms. I n the trials with rennet paste, the results suggest that some f a t hydrolysis in pasteurized milk cheese is beneficial f r o m the standpoint of production of cheddar cheese flavor. Variations were encountered in the fat acidities of cheese made with the same amounts of rennet paste. I f larger lots of cheese had been made, there m i g h t have been more uniformity. Some method of standardization would a p p e a r desirable so that the degree of f a t hydrolysis can be controlled. A considerable difference was noted in the cheese made with rennet paste as a source of lipase and that made with added m u l b e r r y juice. The r a n c i d i t y developed in cheese made with rennet paste was not as objectionable as the r a n c i d i t y produced b y the m u l b e r r y juice. The results suga)est some selective f a t hydrolysis. A slight rancidity d u r i n g the early p a r t of the ripening in cheese made with rennet paste usually disappeared later, while this commonly was not the case with cheese made with m u l b e r r y juice. These results are in general agreement with the suggestion of L a n e and t t a m m e r (3) that lipase f r o m certain sources is not suitable for use in cheddar cheese. Different lots of m u l b e r r y juice showed significant differences in their ability to hydrolyze cheese f a t ; juice f r o m white berries being more lipolytic t h a n juice f r o m red berries. Increased amounts of m u l b e r r y juice did not always show a n increased amount of f a t hydrolysis, even when the same lots of berries were used.
FAT DEGRADATION IN CHEDDAR CHEESE
207
The relation of f a t hydrolysis to flavor in cheddar cheese is f u r t h e r emphasized when process cheese is made f r o m a blend containing some cheese exhibiting f a t hydrolysis. The slight rancidity, a p p a r e n t in certain of the aged cheese showing rather extensive f a t hydrolysis, is diluted when blended with y o u n g cheese so t h a t the resulting process cheese does not have a rancid flavor. I t is also possible that some of the free acids responsible f o r the r a n c i d i t y m a y be volatilized d u r i n g the processing operation. SUMMARY
The f a t acidities of cheddar cheese made f r o m pasteurized milk without added lipase were v e r y similar when the cheese were 3 days old. Increases occurred t h r o u g h o u t the ripening period. The increases were not u n i f o r m with the different lots of cheese a n d could not be correlated with the p i t of the cheese, the acidity of the whey at milling, or the moisture or f a t content of the cheese. The f a t acidities of cheese m a d e with rennet extract and with rennet powder increased at a p p r o x i m a t e l y the same rate. Purified butterfat, obtained f r o m pasteurized sweet cream and held at the cheese ripening t e m p e r a t u r e (50 ° F . ) , did not increase significantly in acidity. Addition of a small amount of r e n n e t paste (13 to 40 g r a m s per 1,000 pounds milk) resulted in an increase in f a t acidity of the cheese. Some of the cheese showed v a r y i n g degrees of rancidity early in the ripening, b u t this r a n c i d i t y disappeared or n e a r l y disappeared before the cheese were 6 months old. The cheese (made with rennet paste) that were not rancid were superior in flavor to the control cheese. The use of a small a m o u n t of rennet paste tended to mask the sour, acid flavor f r e q u e n t l y encountered in the control cheese. Addition of a larger a m o u n t of rennet paste (50 to 225 g r a m s per 1,000 pounds of milk) resulted in a significant increase in f a t acidity of the cheese. All of the cheese showed r a n c i d i t y at some time during the ripening and certain lots were rancid when the cheese were 6 months old. The addition of m u l b e r r y juice to pasteurized milk did not improve the tta~or of the resulting cheese. Small amounts had little effect on the flavor while larger amounts resulted in raneid and unclean flavors. The use of a certain amount of aged cheese showing definite f a t hydrolysis was benefieial f r o m the standpoint of flavor of process cheese. Process cheese containing some aged cheese made with addition of rennet paste had more flavor t h a n process cheese m a d e with an equivalent amount of aged control cheese. REFERENCES
(1) ]3REAZEALE,D. F., AND BIRD/ E . W .
A S t u d y of M e t h o d s f o r the D e t e r m i n a t i o n o f A c i d i t y in ]3utter F a t . JOVR. DAmY ScI., 21: 335-344. 1938. (2) :LANE, C. ]3., AND }IAI~SIEI~, ]3. W. S t u d i e s on the F a t of Cheddar Cheese. I o w a S t a t e Col. J o u r . Sci., 13: 149-155. 1939.
208
F.J.
BABEL AND B. W. HA~£MER
(3) LANE, C. B., AND HAMMER, B . W . Bacteriology of Cheese. VI. Relationship of P a t Hydrolysis to the Ripening of Cheddar Cheese. Iowa Agr. Expt. Sta., Res. Bul. 291. 1941. (4) SANDERS, GEORGE P. A Simplified Quinhydrone Electrode. Application in Determining the H-ion Concentration of Liquids and Semiplasti¢ Solids. Indus. and Engin. Chem., Analyt. Ed., 10: 274-275. 1938. (5) SuzuKI, S. K., HASTINGS, E. G., AND HART, E . B . The Production of Volatile P a t t y Acids and Esters in Cheddar Cheese and Their Relation to the Development of Flavor. Wis. Agr. Expt. Sta., Res. Bul. 11. 1910. (6) VAN SL'YKE,L. a. Investigation of Cheese. Experiments in the Manufacture of Cheese. Influence of Composition of Milk on Composition and Yield of Cheese. A Study of the Process of Ripening of Cheese. N . Y . (Geneva) Agr. Expt. Sta., Bul. 37. 1891. (7) WILSON, H. L. Manufacture of American Cheese from Pasteurized Milk. Natl. Butter and Cheese Jour., 33 (2) : 18, 20, 22, 24-28. 1942.