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Observations on the Whipping Characteristics of Cream
OUR INDUSTRY T O D A Y Observations on the Whipping Characteristics of Cream C. M. B R U H N 1
Cooperative Extension Center for Consumer Research J. C. B R U H N
Cooperative Extension and Department of Food Science and Technology University of California Davis 95616
ABSTRACT
INTRODUCTION
With the application of UHT technology to the processing of whipping creams, consumers may purchase creams with whipping characteristics different from creams processed by conventional pasteurization. This study observed differences in whipping properties among raw, pasteurized, and UHT whipping creams. Whipping time to reach maximum volume, number of days before and after retail sell-by date, and overrun were recorded. Mean whipping time and maximum overrun varied significantly by processor, product composition, and retail cream age. Mean whipping time ranged from 1.6 min for raw unpasteurized creams to 3.4 min for UHT heavy cream without whipping aids. Mean maximum overrun ranged from 141% for UHT her W creams without whipping aids to 216% for UHT whipping creams with aids. There was considerable variation in mean whipping time and mean maximum overrun among processors for creams of the same composition. Regression analysis between whipping time and retail cream age revealed a positive relationship for some product types and a negative relationship for others. Whipping time and maximum overrun of retail whipping creams vary substantiaIly by product type, processing treatment, and processor.
Whipping cream is not an everyday purchase in most households and is often used for special occasions only. Consumers and the dairy industry have certain expectations for the quality of whipping creams with regard to taste, shelf-life, and whipping characteristics. Whipping characteristics recognized within the industry are speed of whipping, overrun, firmness of whipped product, and stability (8). The whipping process forms air cells that are stabilized at the air-water interface by fat globules (8, 12). During whipping, the globules attach to air bubbles; as these air bubbles break and coalesce, the fat clumps. As whipping continues, air cells become smaller and more numerous, fat clumping continues, and the foam increases in volume and rigidity. If whipping continues still further, the fat clumps become so large they rupture the lameilae that enclose the air cells. Air bubbles start to coalesce, overrun decreases, and churning results. Researchers agree that milk fat content, cream temperature, homogenization and pasteurization conditions, and presence of stabilizers and emulsifiers influence whipping creams' functional properties (2, 7, 8, 10, 11, 12). Higher milk fat increases foam firmness and stability but decreases overrun. Because fat solidification is necessary in the formation of a satisfactory foam, cream must be chilled prior to whipping. Pasteurization temperature affects whipping characteristics; higher temperatures generally increase whipping time and reduce overrun. When whipping cream is UHT heated it can also be homogenized to prevent creamplug formation during prolonged storage (8). Homogenizer valve type and pressures, as well as number of homogenization stages, influence overrun through the production of fat clusters of varying sizes (8, 11). Surface-active agents and stabilizers, often added to creams that
Received June 25, 1987. Accepted October 5, 1987. 1Person to whom correspondence should be addressed. 1988 J Dairy Sci 71:857-862
857
858
BRUHN AND BRUHN
undergo UHT treatment, produce a finer foam and affect overrun and foam stability (1, 5, 8,
11). Other factors that influence the whipping characteristics of cream may be less important in today's market. F o r example, early work by Babcock on the influence of aging on the whipping characteristics of pasteurized cream are irrelevant t o d a y since the effects are noticeable only up to 24 h after pasteurization (2). The time required for distribution to the market and the long shelf-life of today's products make it unlikely that consumers buy freshly processed creams. Seasonal variations in composition and properties of raw cream are known to influence whipping cream functionality (6, 8). These variations may be of little importance in the California market, since dairy farms maintain herds in uniform states of lactation throughout the year. Dairy cattle feed composition used in California dairies is also relatively uniform throughout the year. The temperature of processing influences whipping characteristics. In the past, whipping creams were HTST pasteurized, typically at 74°C for 18 s. Such creams have a longer shelf-life and different whipping properties than the raw product. Currently, many whipping creams are processed by UHT methods, at about 138°C for 4 s. The longer shelf-life of these UHT products makes this technology attractive to dairy processors. There has been little recent literature regarding the whipping characteristics of the long-life creams available to consumers today. This study was designed to update the data and identify differences in whipping properties of raw, HTST, and UHT creams. The results of the study could help answer consumer questions regarding the whipping properties of the "new" creams and help establish a current data base on the whipping characteristics of creams. MATERIALS AND METHODS
During a 15-mo period in 1984 to 1985, samples of whipping cream and heavy whipping cream were purchased from retail dairy cases. Samples were transported at 4°C to the laboratory and refrigerated until analyzed. California standards require a minimum of 30% milk fat for whipping cream and 36% milk fat, or more, for heavy whipping cream. Either type of cream Journal of Dairy Science Vol. 71, No. 3, 1988
may have up to .6% stabilizers and emulsifiers (3). Samples from the six major processors of UHT whipping creams in California were obtained. There was only one plant processing raw and one processing pasteurized whipping cream for retail sale in California. Purchased samples represented: raw whipping cream (one processor), pasteurized whipping cream (one processor), UHT whipping cream (four processors), UHT heavy whipping cream (two processors). In order to test for processor variation, 15 samples of pasteurized whipping cream were collected from retail stores in Oregon. Because no variation in functional properties was observed, these samples were included with the pasteurized whipping creams collected in California. Information on the specific time, temperature, and homogenization pressures used in the UHT creams was unavailable due to proprietary considerations. Products were stored at 4 to 5°C a minimum of 24 h before whipping to allow for temperature stabilization and solidification of fat. Whipping creams were evaluated throughout their shelf-lives: from 46 d before to 28 d after the retail sell-by date coded on the carton for UHT whipping creams, from 4 d before to 17 d after for pasteurized whipping creams, and from 11 d before to 2 d after for raw whipping creams. Half-pint (.24-L) samples were whipped in a chilled bowl to maximum overrun in a Kitchenaid mixer model K5A operating at speed six (about 150 rpm). Whipping times were taken at 15-s intervals for products that reached maximum overrun in less than 2.5 rain and at 30-s intervals for products that required more than 2.5 min. Experience showed that overrun did not vary within these time intervals and that variation due to subjective visual evaluation was reduced. Maximum overrun and whipping time to reach maximum overrun were recorded. Overrun was calculated using a 112-ml container and the standard overrun formula: [(weight liquid - weight foam)/weight foam)] x 100 = percent overrun. According to package labels, all raw and pasteurized whipping creams and one UHT heavy cream contained no additives. Processor 3 used carrageenan, dextrose, and guar gum for both whipping and heavy cream. Plant 4 used mono- and diglycerides, polysorbate 60, and
OUR INDUSTRY TODAY carrageenan. Plants 5 and 6 used m o n o - a n d diglycerides, polysorbate 80, and carrageenan. Plant 6 used this combination in both whipping and heavy cream.
RESULTS AND DISCUSSION
Whipping times required to reach maximum overrun varied significantly according to processing method and product type (Table 1). Whipping time was shortest for raw cream; pasteurized cream required the next shortest time. These findings are consistent with Babcock's early work (2) and may be due to changes in the fat globule membrane (9). The UHT products required longer whipping times than raw or pasteurized products. The UHT heavy whipping creams required slightly less whipping time to reach maximum overrun than UHT regular whipping creams. The UHT heavy creams without additives required the longest whipping time. Mean overrun of all creams varied from a low of 143% for UHT whipping cream from one processor to a high of 216% (Table 2). Raw cream had intermediate overrun values. Within any processor, heavy whipping creams achieved lower overruns than regular whipping creams.
859
This result is consistent with earlier work that showed that increases in fat content decreased overrun (7, 12). The UHT heavy cream without additives achieved a lower overrun than raw or pasteurized regular whipping cream. That additives or processing technique can overcome the lower whippability of UHT products is apparent from the high overrun for creams from processors 4 and 6. To determine the effects of product age on whipping qualities, regression analyses were completed in which whipping time and overrun were each regressed against days before retail sell-by date (4). A positive correlation was found between whipping time and cream age for pasteurized cream and both heavy UHT creams that contained additives (Figure 1). As the creams approached sell-by date, they required longer whipping times. In contrast, UHT heavy cream without additives required shorter whipping times as the cream aged. Raw cream exhibited a negative correlation with age significant only at 10%. No correlation was found between age and whipping time for the UHT regular whipping creams. A negative correlation was revealed between cream age (as measured by retail sell-by date) and overrun for raw cream and for one proces-
TABLE 1. Mean whipping times to reach maximum overrun for different whipping creams. Processor
Method 1
Samples2
Whipping cream
t 2 3
Raw HTST UHT
30 71 21 (28)
4
UHT
19
5
UHT
15
6
UHT
23 (30)
1.6 a 1~9b 2.5 c'd'e (additives) 2.7 e (additives) 2.7 e (additives) 2.8 e (additives)
6
UHT
(30)
Heavy cream (min)
...
2.0 b ,c (additives)
2.3 d (additives) 3.4f (no additives)
a'b'c'd'e'fwhippingtimes with different superscripts are statistically different (P<.05). i RAW = Raw product. 2Numbers in parentheses refer to sample numbers for heavy cream. Journal of Dairy Science Vol. 71, No. 3, 1988
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BRUHN AND BRUHN
TABLE 2. Mean maximum overrun for different whipping creams. Overrun Processor
Method I
Samples 2
Heavy cream
Whipping cream (%)
5
UHT
15
143 a (additives)
2
PAST
71
158 b
1
RAW
30
172 c
3
UHT
21 (28)
180 c (additives)
4
UHT
19
198 d (additives)
6
UHT
23 (30)
216 e (additives)
141 a (no additives)
6
UHT
(30)
.. •
194 d (additives)
160 b (additives)
a'b'c'd'eoverrun values with different superscript letters are statistically different (P<.05)• 1 PAST = Pasteurized; RAW = raw product. 2 Numbers in parentheses refer to sample numbers for heavy cream.
s o r ' s U H T h e a v y c r e a m t h a t c o n t a i n e d additives (Figure 2). As these creams aged, o v e r r u n decreased• T h e U H T h e a v y c r e a m w i t h o u t additives e x h i b i t e d a positive t r e n d ( P < . 1 0 ) , i.e., o v e r r u n i n c r e a s e d w i t h c r e a m age. T h e r e fore, b o t h w h i p p i n g t i m e a n d o v e r r u n were r e l a t e d to c r e a m age, b u t t h e s e r e l a t i o n s h i p s a p p e a r e d t o b e u n i q u e f o r each p r o c e s s o r a n d product. T o i d e n t i f y a d d i t i o n a l f a c t o r s related to v o l u m e increase in w h i p p i n g cream, regression analysis was c o m p l e t e d in w h i c h o v e r r u n was t h e d e p e n d e n t variable a n d t i m e to reach m a x i m u m o v e r r u n was t h e i n d e p e n d e n t variable. This analysis related w h i p p i n g t i m e t o m a x i m u m o v e r r u n for m a n y samples, r a t h e r t h a n t h e c h a n g e in o v e r r u n o b t a i n e d as a single s a m p l e of c r e a m was w h i p p e d . T h e analysis revealed t h a t o v e r r u n was positively related to w h i p p i n g t i m e for raw cream, f o r p a s t e u r i z e d cream, a n d f o r o n e p r o c e s s o r ' s U H T w h i p p i n g c r e a m (Figure 3). T h e s e f i n d i n g s mean that those products that required a longer whipping time reached a higher overrun than t h o s e t h a t r e a c h e d m a x i m u m o v e r r u n quickly. A negative c o r r e l a t i o n was f o u n d f o r w h i p p i n g time and overrun for one processor's heavy Journal of Dairy Science Vol. 71, No. 3, 1988
c r e a m t h a t c o n t a i n e d additives. T h e r e was n o significant r e l a t i o n s h i p b e t w e e n w h i p p i n g t i m e a n d o v e r r u n for t h e o t h e r p r o c e s s o r ' s p r o d u c t s . O f w h a t significance are t h e s e data? Whipping creams were viewed h i s t o r i c a l l y as o n e o f t h e m o s t t r o u b l e s o m e dairy p r o d u c t s b e c a u s e
4.0 3.5
" ~ / L - . ~ / ~ . ~
~ 3.0 ~" 2.5
2 2.0 1.5 1.0 -50
= -40
i -30
i -20
i -10
i 0
~ 10
i 20
i 30
40
Cream Age (days)
Figure 1. Whipping time required to reach maximum overrun as influenced by the age of the cream. Cream age was determined in relation to retail sell-bydate, which was called 0. Cream types and significance: raw, plant 1 ( . . . . ), P<.10; pasteurized, plant 2 ( . . . . . . ), P<.01; heavy creams, UHT: no additives, plant 6 (--~<~), P<.10; additives, plant 6 (. . . . ), P<.01; additives, plant 3 ( . . . . . ), P<.01.
OUR INDUSTRY TODAY
86 1
240 I
210 200
/
220
190
200
/~
180
==17o \
O 160
\
150
/
O 160
\
.7../....
140
140 -50
.s.~ "~'~
180 1
i
i
i
i
i
i
i
i
-40
-30
-20
-10
0
10
20
30
1.0
40
1.5
2.0
2.5
3.0
3.5
4.0
Whipping time to reach maximum overrun (minutes)
Age (days)
Figure 2. The effect of cream age on maximum overrun. Age is determined in relation to retail sell-by date, which is called 0. Cream types and significance: raw, plant 1 ( . . . . ), P<.05; UHT: heavy cream, additives, plant 6 ( ), P<.01; heavy cream, no additives, plant 6 ( . . . . . ), P<.I.
Figure 3. Whipping time required to reach maximum overrun as related to maximum overrun. Cream types and significance: raw, plant 1 ( . . . . ), P<.O1 ; pasteurized, plant 2 ( . . . . . . ), P<.05; UHT, plant 4 ( . . . . . ), P<.O1; heavy cream, additives, plant 6 ( ), P<.O1.
t h e y distressed c o n s u m e r s w h e n t h e y failed to w h i p or were spoiled b e f o r e t h e y could b e used (9). T h e results of this s t u d y reveal t h a t t o d a y ' s U H T w h i p p i n g c r e a m s ' f u n c t i o n a l qualities vary s u b s t a n t i a l l y a m o n g m a n u f a c t u r e r s . T h e s e varia t i o n s could b e a t t r i b u t e d to d i f f e r e n c e s in p a s t e u r i z a t i o n or h o m o g e n i z a t i o n p r o c e d u r e s a n d to t h e p r e s e n c e o f additives. C r e a m s f r o m t h o s e processors t h a t used m o n o - a n d diglycerides, p o l y s o r b a t e 80, a n d c a r r a g e e n a n generally p r o d u c e d t h e g r e a t e s t o v e r r u n ( T a b l e 3). N o t e t h a t this g r o u p o f w h i p p i n g creams i n c l u d e d t h e p r o d u c t s w i t h
t h e h i g h e s t o v e r r u n b u t also o n e w i t h t h e lowest overrun. Creams that contained monoa n d diglycerides, p o l y s o r b a t e s , a n d c a r r a g e e n a n generally r e q u i r e d t h e longest w h i p p i n g t i m e s to r e a c h m a x i m u m o v e r r u n ( T a b l e 4). CONCLUSIONS
T h e U H T creams t o o k a b o u t 40% longer to w h i p t h a n raw a n d p a s t e u r i z e d creams. H e a v y creams w h i p p e d in a b o u t 20% less t i m e a n d to a l o w e r o v e r r u n t h a n regular w h i p p i n g creams. O v e r r u n was g r e a t e s t f r o m U H T p r o d u c t s ; h o w e v e r , this o v e r r u n varied significantly
TABLE 3. Relationship between additives and maximum overrun in whipping cream .1 Additives
None
Carrageenan, dextrose, guar
158 b
180 c
172 c
160 b (heavy)
Mono & Di Gly, 2 Poly-60, carrageenan Overrun(%) 198 d
Mono & Di Gly, Poly-80, carrageenan
143 a 216 e
141a(heavy)
194 d (heavy)
a'b'c'd'evalues with different superscripts are statistically different (P<.05). 1 Samples are whipping cream unless identified as heavy whipping cream (heavy). 2 Mono & Di Gly = Mono- and diglycerides, Poly = polysorbate. Journal of Dairy Science Vol. 71, No. 3, 1988
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BRUHN AND BRUHN
TABLE 4. Relationship between additives and whipping time required to reach maximum overrun. Additives
None
Carrageenan, dextrose, guar
1.6 a
2.5c,d, e
1.9 b
2.0 b'c (heavy)
Mono & Di Gly, 2 Poly-60, carrageenan Time (rain) 2.7 e
Mono & Di Gly, Poly-80, carrageenan
2.7 e 2.8 e
3.4 f (heavy)
2.3 d (heavy)
a'b'c'd'e'fvalues with different superscripts are statistically different (P<.05). 1 Samples are whipping cream unless identified as heavy whipping cream (heavy). 2Mono & Di Gly = Mono- and diglycerides, Poly = polysorbate.
a m o n g processors. G r e a t e s t overrun a m o n g w h i p p i n g creams (216%) was o b t a i n e d w i t h creams f r o m a p r o c e s s o r t h a t u s e d m o n o - and diglycerides, p o l y s o r b a t e - 8 0 , and carrageenan; l o w e s t o v e r r u n (143%) was o b t a i n e d w i t h creams f r o m a p r o c e s s o r t h a t used the s a m e additives. A n i m p o r t a n t c o n s i d e r a t i o n for p r o c e s s o r s is w h e t h e r t h e c o n s u m e r can i d e n t i f y t h e s e differences. This s t u d y was n o t d e s i g n e d to evaluate c o n s u m e r awareness or p r e f e r e n c e . We t h i n k t h a t c o n s u m e r s can distinguish b e t w e e n t h e e x t r e m e s - a c r e a m t h a t reaches m a x i m u m o v e r r u n a f t e r 1.5 t o 2 rain o f w h i p p i n g a n d o n e t h a t requires 3 to 4 min. It is likely t h a t a c o n s u m e r can also distinguish b e t w e e n a cream t h a t w h i p s to a p p r o x i m a t e l y 140% o v e r r u n and o n e t h a t w h i p s t o over 200% overrun. Processors w h o c o n s i d e r changing to U H T s h o u l d b e aware o f t h e d i f f e r e n c e s a m o n g t h e s e p r o d u c t s . ACKNOWLEDGMENTS T o n y F r a n k e ' s statistical analysis o f this data is a p p r e c i a t e d . REFERENCES 1 Aggarwal,
M. L. 1974. Ultra-pasteurization of
Journal of Dairy Science Vol. 71, No. 3, 1988
whipping cream. J. Milk Food Teehnol. 38:36. 2 Babcock, C. J. 1922. The whipping quality of cream. Bull. No. 1075. Dep. Agric., Washington, DC. 3 California Department of Food and Agriculture. 1979. Standards for dairy products, DS-118. Bur. Milk and Dairy Foods Control, Sacramento, CA. 4 Johnson, J. 1963. Econometric methods. 2nd ed. McGraw-Hill, New York, NY. 5 Kieseker, F. G., and J. G. Zadow. 1973. Factors influencing the preparation "of UHT whipping cream. Aust. J. Dairy Technol. 28:165. 6 Keogh, M. K. 1978. Seasonal effects of colloid additives on some properties of UHT 35% fat creams. Ir. J. Food Sci. Technol. 2:77. 7 Muir, D. D., J. M. Banks, A. K. Powell, and A.W.M. Sweetsur. 1983. Milk composition; manufacturing properties. Proc. Nutr. Soc. 42: 385. 8 Mulder, H., and P. Walstra. 1974. The milk fat globule. Commonw. Agric. Bur., Farmham Royal, Buckinghamshire, Engt. 9 Sommer, H. H. 1952. Market milk and related products. Publ. by author, Madison, Wl. 10 Thome, K. E., and G. Eriksson. 1973. The foaming properties of cream. 1. Substances in milk increasing the whippability of creams. Milchwissenschaft 28:502. 11 Towler, C. 1986. Measurement of whipping properties of cream and the effect of cream variation on whipping. N.Z.J. Dairy Sci. Technol. 21:79. 12 Walstra, P., and R. Jennes. 1984. Dairy chemistry and physics. John Wiley and Sons, New York, NY.
Cooperative Extension Center for Consumer Research J. C. B R U H N
Cooperative Extension and Department of Food Science and Technology University of California Davis 95616
ABSTRACT
INTRODUCTION
With the application of UHT technology to the processing of whipping creams, consumers may purchase creams with whipping characteristics different from creams processed by conventional pasteurization. This study observed differences in whipping properties among raw, pasteurized, and UHT whipping creams. Whipping time to reach maximum volume, number of days before and after retail sell-by date, and overrun were recorded. Mean whipping time and maximum overrun varied significantly by processor, product composition, and retail cream age. Mean whipping time ranged from 1.6 min for raw unpasteurized creams to 3.4 min for UHT heavy cream without whipping aids. Mean maximum overrun ranged from 141% for UHT her W creams without whipping aids to 216% for UHT whipping creams with aids. There was considerable variation in mean whipping time and mean maximum overrun among processors for creams of the same composition. Regression analysis between whipping time and retail cream age revealed a positive relationship for some product types and a negative relationship for others. Whipping time and maximum overrun of retail whipping creams vary substantiaIly by product type, processing treatment, and processor.
Whipping cream is not an everyday purchase in most households and is often used for special occasions only. Consumers and the dairy industry have certain expectations for the quality of whipping creams with regard to taste, shelf-life, and whipping characteristics. Whipping characteristics recognized within the industry are speed of whipping, overrun, firmness of whipped product, and stability (8). The whipping process forms air cells that are stabilized at the air-water interface by fat globules (8, 12). During whipping, the globules attach to air bubbles; as these air bubbles break and coalesce, the fat clumps. As whipping continues, air cells become smaller and more numerous, fat clumping continues, and the foam increases in volume and rigidity. If whipping continues still further, the fat clumps become so large they rupture the lameilae that enclose the air cells. Air bubbles start to coalesce, overrun decreases, and churning results. Researchers agree that milk fat content, cream temperature, homogenization and pasteurization conditions, and presence of stabilizers and emulsifiers influence whipping creams' functional properties (2, 7, 8, 10, 11, 12). Higher milk fat increases foam firmness and stability but decreases overrun. Because fat solidification is necessary in the formation of a satisfactory foam, cream must be chilled prior to whipping. Pasteurization temperature affects whipping characteristics; higher temperatures generally increase whipping time and reduce overrun. When whipping cream is UHT heated it can also be homogenized to prevent creamplug formation during prolonged storage (8). Homogenizer valve type and pressures, as well as number of homogenization stages, influence overrun through the production of fat clusters of varying sizes (8, 11). Surface-active agents and stabilizers, often added to creams that
Received June 25, 1987. Accepted October 5, 1987. 1Person to whom correspondence should be addressed. 1988 J Dairy Sci 71:857-862
857
858
BRUHN AND BRUHN
undergo UHT treatment, produce a finer foam and affect overrun and foam stability (1, 5, 8,
11). Other factors that influence the whipping characteristics of cream may be less important in today's market. F o r example, early work by Babcock on the influence of aging on the whipping characteristics of pasteurized cream are irrelevant t o d a y since the effects are noticeable only up to 24 h after pasteurization (2). The time required for distribution to the market and the long shelf-life of today's products make it unlikely that consumers buy freshly processed creams. Seasonal variations in composition and properties of raw cream are known to influence whipping cream functionality (6, 8). These variations may be of little importance in the California market, since dairy farms maintain herds in uniform states of lactation throughout the year. Dairy cattle feed composition used in California dairies is also relatively uniform throughout the year. The temperature of processing influences whipping characteristics. In the past, whipping creams were HTST pasteurized, typically at 74°C for 18 s. Such creams have a longer shelf-life and different whipping properties than the raw product. Currently, many whipping creams are processed by UHT methods, at about 138°C for 4 s. The longer shelf-life of these UHT products makes this technology attractive to dairy processors. There has been little recent literature regarding the whipping characteristics of the long-life creams available to consumers today. This study was designed to update the data and identify differences in whipping properties of raw, HTST, and UHT creams. The results of the study could help answer consumer questions regarding the whipping properties of the "new" creams and help establish a current data base on the whipping characteristics of creams. MATERIALS AND METHODS
During a 15-mo period in 1984 to 1985, samples of whipping cream and heavy whipping cream were purchased from retail dairy cases. Samples were transported at 4°C to the laboratory and refrigerated until analyzed. California standards require a minimum of 30% milk fat for whipping cream and 36% milk fat, or more, for heavy whipping cream. Either type of cream Journal of Dairy Science Vol. 71, No. 3, 1988
may have up to .6% stabilizers and emulsifiers (3). Samples from the six major processors of UHT whipping creams in California were obtained. There was only one plant processing raw and one processing pasteurized whipping cream for retail sale in California. Purchased samples represented: raw whipping cream (one processor), pasteurized whipping cream (one processor), UHT whipping cream (four processors), UHT heavy whipping cream (two processors). In order to test for processor variation, 15 samples of pasteurized whipping cream were collected from retail stores in Oregon. Because no variation in functional properties was observed, these samples were included with the pasteurized whipping creams collected in California. Information on the specific time, temperature, and homogenization pressures used in the UHT creams was unavailable due to proprietary considerations. Products were stored at 4 to 5°C a minimum of 24 h before whipping to allow for temperature stabilization and solidification of fat. Whipping creams were evaluated throughout their shelf-lives: from 46 d before to 28 d after the retail sell-by date coded on the carton for UHT whipping creams, from 4 d before to 17 d after for pasteurized whipping creams, and from 11 d before to 2 d after for raw whipping creams. Half-pint (.24-L) samples were whipped in a chilled bowl to maximum overrun in a Kitchenaid mixer model K5A operating at speed six (about 150 rpm). Whipping times were taken at 15-s intervals for products that reached maximum overrun in less than 2.5 rain and at 30-s intervals for products that required more than 2.5 min. Experience showed that overrun did not vary within these time intervals and that variation due to subjective visual evaluation was reduced. Maximum overrun and whipping time to reach maximum overrun were recorded. Overrun was calculated using a 112-ml container and the standard overrun formula: [(weight liquid - weight foam)/weight foam)] x 100 = percent overrun. According to package labels, all raw and pasteurized whipping creams and one UHT heavy cream contained no additives. Processor 3 used carrageenan, dextrose, and guar gum for both whipping and heavy cream. Plant 4 used mono- and diglycerides, polysorbate 60, and
OUR INDUSTRY TODAY carrageenan. Plants 5 and 6 used m o n o - a n d diglycerides, polysorbate 80, and carrageenan. Plant 6 used this combination in both whipping and heavy cream.
RESULTS AND DISCUSSION
Whipping times required to reach maximum overrun varied significantly according to processing method and product type (Table 1). Whipping time was shortest for raw cream; pasteurized cream required the next shortest time. These findings are consistent with Babcock's early work (2) and may be due to changes in the fat globule membrane (9). The UHT products required longer whipping times than raw or pasteurized products. The UHT heavy whipping creams required slightly less whipping time to reach maximum overrun than UHT regular whipping creams. The UHT heavy creams without additives required the longest whipping time. Mean overrun of all creams varied from a low of 143% for UHT whipping cream from one processor to a high of 216% (Table 2). Raw cream had intermediate overrun values. Within any processor, heavy whipping creams achieved lower overruns than regular whipping creams.
859
This result is consistent with earlier work that showed that increases in fat content decreased overrun (7, 12). The UHT heavy cream without additives achieved a lower overrun than raw or pasteurized regular whipping cream. That additives or processing technique can overcome the lower whippability of UHT products is apparent from the high overrun for creams from processors 4 and 6. To determine the effects of product age on whipping qualities, regression analyses were completed in which whipping time and overrun were each regressed against days before retail sell-by date (4). A positive correlation was found between whipping time and cream age for pasteurized cream and both heavy UHT creams that contained additives (Figure 1). As the creams approached sell-by date, they required longer whipping times. In contrast, UHT heavy cream without additives required shorter whipping times as the cream aged. Raw cream exhibited a negative correlation with age significant only at 10%. No correlation was found between age and whipping time for the UHT regular whipping creams. A negative correlation was revealed between cream age (as measured by retail sell-by date) and overrun for raw cream and for one proces-
TABLE 1. Mean whipping times to reach maximum overrun for different whipping creams. Processor
Method 1
Samples2
Whipping cream
t 2 3
Raw HTST UHT
30 71 21 (28)
4
UHT
19
5
UHT
15
6
UHT
23 (30)
1.6 a 1~9b 2.5 c'd'e (additives) 2.7 e (additives) 2.7 e (additives) 2.8 e (additives)
6
UHT
(30)
Heavy cream (min)
...
2.0 b ,c (additives)
2.3 d (additives) 3.4f (no additives)
a'b'c'd'e'fwhippingtimes with different superscripts are statistically different (P<.05). i RAW = Raw product. 2Numbers in parentheses refer to sample numbers for heavy cream. Journal of Dairy Science Vol. 71, No. 3, 1988
860
BRUHN AND BRUHN
TABLE 2. Mean maximum overrun for different whipping creams. Overrun Processor
Method I
Samples 2
Heavy cream
Whipping cream (%)
5
UHT
15
143 a (additives)
2
PAST
71
158 b
1
RAW
30
172 c
3
UHT
21 (28)
180 c (additives)
4
UHT
19
198 d (additives)
6
UHT
23 (30)
216 e (additives)
141 a (no additives)
6
UHT
(30)
.. •
194 d (additives)
160 b (additives)
a'b'c'd'eoverrun values with different superscript letters are statistically different (P<.05)• 1 PAST = Pasteurized; RAW = raw product. 2 Numbers in parentheses refer to sample numbers for heavy cream.
s o r ' s U H T h e a v y c r e a m t h a t c o n t a i n e d additives (Figure 2). As these creams aged, o v e r r u n decreased• T h e U H T h e a v y c r e a m w i t h o u t additives e x h i b i t e d a positive t r e n d ( P < . 1 0 ) , i.e., o v e r r u n i n c r e a s e d w i t h c r e a m age. T h e r e fore, b o t h w h i p p i n g t i m e a n d o v e r r u n were r e l a t e d to c r e a m age, b u t t h e s e r e l a t i o n s h i p s a p p e a r e d t o b e u n i q u e f o r each p r o c e s s o r a n d product. T o i d e n t i f y a d d i t i o n a l f a c t o r s related to v o l u m e increase in w h i p p i n g cream, regression analysis was c o m p l e t e d in w h i c h o v e r r u n was t h e d e p e n d e n t variable a n d t i m e to reach m a x i m u m o v e r r u n was t h e i n d e p e n d e n t variable. This analysis related w h i p p i n g t i m e t o m a x i m u m o v e r r u n for m a n y samples, r a t h e r t h a n t h e c h a n g e in o v e r r u n o b t a i n e d as a single s a m p l e of c r e a m was w h i p p e d . T h e analysis revealed t h a t o v e r r u n was positively related to w h i p p i n g t i m e for raw cream, f o r p a s t e u r i z e d cream, a n d f o r o n e p r o c e s s o r ' s U H T w h i p p i n g c r e a m (Figure 3). T h e s e f i n d i n g s mean that those products that required a longer whipping time reached a higher overrun than t h o s e t h a t r e a c h e d m a x i m u m o v e r r u n quickly. A negative c o r r e l a t i o n was f o u n d f o r w h i p p i n g time and overrun for one processor's heavy Journal of Dairy Science Vol. 71, No. 3, 1988
c r e a m t h a t c o n t a i n e d additives. T h e r e was n o significant r e l a t i o n s h i p b e t w e e n w h i p p i n g t i m e a n d o v e r r u n for t h e o t h e r p r o c e s s o r ' s p r o d u c t s . O f w h a t significance are t h e s e data? Whipping creams were viewed h i s t o r i c a l l y as o n e o f t h e m o s t t r o u b l e s o m e dairy p r o d u c t s b e c a u s e
4.0 3.5
" ~ / L - . ~ / ~ . ~
~ 3.0 ~" 2.5
2 2.0 1.5 1.0 -50
= -40
i -30
i -20
i -10
i 0
~ 10
i 20
i 30
40
Cream Age (days)
Figure 1. Whipping time required to reach maximum overrun as influenced by the age of the cream. Cream age was determined in relation to retail sell-bydate, which was called 0. Cream types and significance: raw, plant 1 ( . . . . ), P<.10; pasteurized, plant 2 ( . . . . . . ), P<.01; heavy creams, UHT: no additives, plant 6 (--~<~), P<.10; additives, plant 6 (. . . . ), P<.01; additives, plant 3 ( . . . . . ), P<.01.
OUR INDUSTRY TODAY
86 1
240 I
210 200
/
220
190
200
/~
180
==17o \
O 160
\
150
/
O 160
\
.7../....
140
140 -50
.s.~ "~'~
180 1
i
i
i
i
i
i
i
i
-40
-30
-20
-10
0
10
20
30
1.0
40
1.5
2.0
2.5
3.0
3.5
4.0
Whipping time to reach maximum overrun (minutes)
Age (days)
Figure 2. The effect of cream age on maximum overrun. Age is determined in relation to retail sell-by date, which is called 0. Cream types and significance: raw, plant 1 ( . . . . ), P<.05; UHT: heavy cream, additives, plant 6 ( ), P<.01; heavy cream, no additives, plant 6 ( . . . . . ), P<.I.
Figure 3. Whipping time required to reach maximum overrun as related to maximum overrun. Cream types and significance: raw, plant 1 ( . . . . ), P<.O1 ; pasteurized, plant 2 ( . . . . . . ), P<.05; UHT, plant 4 ( . . . . . ), P<.O1; heavy cream, additives, plant 6 ( ), P<.O1.
t h e y distressed c o n s u m e r s w h e n t h e y failed to w h i p or were spoiled b e f o r e t h e y could b e used (9). T h e results of this s t u d y reveal t h a t t o d a y ' s U H T w h i p p i n g c r e a m s ' f u n c t i o n a l qualities vary s u b s t a n t i a l l y a m o n g m a n u f a c t u r e r s . T h e s e varia t i o n s could b e a t t r i b u t e d to d i f f e r e n c e s in p a s t e u r i z a t i o n or h o m o g e n i z a t i o n p r o c e d u r e s a n d to t h e p r e s e n c e o f additives. C r e a m s f r o m t h o s e processors t h a t used m o n o - a n d diglycerides, p o l y s o r b a t e 80, a n d c a r r a g e e n a n generally p r o d u c e d t h e g r e a t e s t o v e r r u n ( T a b l e 3). N o t e t h a t this g r o u p o f w h i p p i n g creams i n c l u d e d t h e p r o d u c t s w i t h
t h e h i g h e s t o v e r r u n b u t also o n e w i t h t h e lowest overrun. Creams that contained monoa n d diglycerides, p o l y s o r b a t e s , a n d c a r r a g e e n a n generally r e q u i r e d t h e longest w h i p p i n g t i m e s to r e a c h m a x i m u m o v e r r u n ( T a b l e 4). CONCLUSIONS
T h e U H T creams t o o k a b o u t 40% longer to w h i p t h a n raw a n d p a s t e u r i z e d creams. H e a v y creams w h i p p e d in a b o u t 20% less t i m e a n d to a l o w e r o v e r r u n t h a n regular w h i p p i n g creams. O v e r r u n was g r e a t e s t f r o m U H T p r o d u c t s ; h o w e v e r , this o v e r r u n varied significantly
TABLE 3. Relationship between additives and maximum overrun in whipping cream .1 Additives
None
Carrageenan, dextrose, guar
158 b
180 c
172 c
160 b (heavy)
Mono & Di Gly, 2 Poly-60, carrageenan Overrun(%) 198 d
Mono & Di Gly, Poly-80, carrageenan
143 a 216 e
141a(heavy)
194 d (heavy)
a'b'c'd'evalues with different superscripts are statistically different (P<.05). 1 Samples are whipping cream unless identified as heavy whipping cream (heavy). 2 Mono & Di Gly = Mono- and diglycerides, Poly = polysorbate. Journal of Dairy Science Vol. 71, No. 3, 1988
862
BRUHN AND BRUHN
TABLE 4. Relationship between additives and whipping time required to reach maximum overrun. Additives
None
Carrageenan, dextrose, guar
1.6 a
2.5c,d, e
1.9 b
2.0 b'c (heavy)
Mono & Di Gly, 2 Poly-60, carrageenan Time (rain) 2.7 e
Mono & Di Gly, Poly-80, carrageenan
2.7 e 2.8 e
3.4 f (heavy)
2.3 d (heavy)
a'b'c'd'e'fvalues with different superscripts are statistically different (P<.05). 1 Samples are whipping cream unless identified as heavy whipping cream (heavy). 2Mono & Di Gly = Mono- and diglycerides, Poly = polysorbate.
a m o n g processors. G r e a t e s t overrun a m o n g w h i p p i n g creams (216%) was o b t a i n e d w i t h creams f r o m a p r o c e s s o r t h a t u s e d m o n o - and diglycerides, p o l y s o r b a t e - 8 0 , and carrageenan; l o w e s t o v e r r u n (143%) was o b t a i n e d w i t h creams f r o m a p r o c e s s o r t h a t used the s a m e additives. A n i m p o r t a n t c o n s i d e r a t i o n for p r o c e s s o r s is w h e t h e r t h e c o n s u m e r can i d e n t i f y t h e s e differences. This s t u d y was n o t d e s i g n e d to evaluate c o n s u m e r awareness or p r e f e r e n c e . We t h i n k t h a t c o n s u m e r s can distinguish b e t w e e n t h e e x t r e m e s - a c r e a m t h a t reaches m a x i m u m o v e r r u n a f t e r 1.5 t o 2 rain o f w h i p p i n g a n d o n e t h a t requires 3 to 4 min. It is likely t h a t a c o n s u m e r can also distinguish b e t w e e n a cream t h a t w h i p s to a p p r o x i m a t e l y 140% o v e r r u n and o n e t h a t w h i p s t o over 200% overrun. Processors w h o c o n s i d e r changing to U H T s h o u l d b e aware o f t h e d i f f e r e n c e s a m o n g t h e s e p r o d u c t s . ACKNOWLEDGMENTS T o n y F r a n k e ' s statistical analysis o f this data is a p p r e c i a t e d . REFERENCES 1 Aggarwal,
M. L. 1974. Ultra-pasteurization of
Journal of Dairy Science Vol. 71, No. 3, 1988
whipping cream. J. Milk Food Teehnol. 38:36. 2 Babcock, C. J. 1922. The whipping quality of cream. Bull. No. 1075. Dep. Agric., Washington, DC. 3 California Department of Food and Agriculture. 1979. Standards for dairy products, DS-118. Bur. Milk and Dairy Foods Control, Sacramento, CA. 4 Johnson, J. 1963. Econometric methods. 2nd ed. McGraw-Hill, New York, NY. 5 Kieseker, F. G., and J. G. Zadow. 1973. Factors influencing the preparation "of UHT whipping cream. Aust. J. Dairy Technol. 28:165. 6 Keogh, M. K. 1978. Seasonal effects of colloid additives on some properties of UHT 35% fat creams. Ir. J. Food Sci. Technol. 2:77. 7 Muir, D. D., J. M. Banks, A. K. Powell, and A.W.M. Sweetsur. 1983. Milk composition; manufacturing properties. Proc. Nutr. Soc. 42: 385. 8 Mulder, H., and P. Walstra. 1974. The milk fat globule. Commonw. Agric. Bur., Farmham Royal, Buckinghamshire, Engt. 9 Sommer, H. H. 1952. Market milk and related products. Publ. by author, Madison, Wl. 10 Thome, K. E., and G. Eriksson. 1973. The foaming properties of cream. 1. Substances in milk increasing the whippability of creams. Milchwissenschaft 28:502. 11 Towler, C. 1986. Measurement of whipping properties of cream and the effect of cream variation on whipping. N.Z.J. Dairy Sci. Technol. 21:79. 12 Walstra, P., and R. Jennes. 1984. Dairy chemistry and physics. John Wiley and Sons, New York, NY.