STRUCTURAL AND PALATABILITY TRAITS OF GROUND BEEF HOT BONED, CHILLED AND FROZEN MUSCLE

Transcription

1 STRUCTURAL AND PALATABILITY TRAITS OF GROUND BEEF HOT BONED, CHILLED AND FROZEN MUSCLE by Robert P. Nusbaum* Introduction sample. Thc freezing rates selected were calculated as the amount of time necessary for the internal temperature of the pattic to change from +5"C to -5 C during the freezing process. These rates were accomplished by a -80 C CO, cryogenic tunnel ( 6 minute rate), a -30 C blast freezer (30 minute rate), a -15 C blast freezer (80 minute rate) and a -10 C still air freezer (100 minute rate). The hamburger or ground beef pattie has emerged as a traditional and integral component of the American diet. In 1970 about 20%of the beef consumed in this country was consumed in the ground form. Today, the beef consumed is approximately 45% with predictions of 60% by the early 1980's. Convenience, price, palatability and versatility are all reasons for the increasing volume, but no small part of this increase is being contributed by the fast-food industry. Pattie formulations were accomplished by hydroflaking previously frozen, coarse ground (2.54 cm plate) trim, then grinding both fresh trim and frozenflaked trim through a 0.95 cm plate, mixing for 60 seconds and regrinding through a 0.32 cm plate. Prerigor meat was coarse ground (2.54 cm plate) immediately after boning hot carcasses, chilled with CO, to a temperature of 5"C, then ground, mixed and reground as previously stated. Each pattie formulation was then mechanically formed into patties weighing approximately grams (11.0 cm diameter, 1 cm thickness) with a Holymatic Model 500'4 pattie machine. Patties from each formulation were then divided into five groups, four for freezing and one for unfrozen comparisons. As ground beef pattie production increases to meet the growing demand of the fast-food industry, new knowledge in the field of ground beef handling systems is essential. One key area deals with freezing methods employed to maintain ground beef pattie quality. Another major area includes the use of varying proportions of fresh (non-frozen) and frozen meat for ground beef pattie formulations. Also, energy limitations and production inefficiencies have created current interest in the use of pre-rigor meat in ground beef pattie production. In an attempt to investigate ground beef pattie production methods, this study was undertaken to evaluate and compare the effects of six different pattie formulations and four freezing rates on ground beef pattie structure. Structural differences due to freezing and/or pattie formulation were related to palatability and quality traits. Material Six pattie formulations (20%fat) were studied: 1) 0% frozen-flaked trim, 100% fresh trim 2) 20% frozen-flaked trim, 80% fresh trim 3 ) 50% frozen-flaked trim, 50%fresh trim 4) loa%frozen-flaked trim, All of the pattie samples evaluated by light ( L M ) and scanning electron microscopy ( S E M ) were prepared without chemical fixation. Once frozen, patties remained in that state until freeze-drying or freezemicrotoming procedures. Every attempt was made to prevent recrystallization during sample removal and preparation to ensure that cavities seen by LM and SEM were replicas of the ice crystals formed in the initial freezing. Techniques used for sample preparation in this study have been utilized successfully by several other workers investigating structural damagc caused by freezing (Koonz and Ramsbottom, 1939; Wang et al., 1954; Menz and Luyet, 1961; Boyd, 1978). 0% fresh trim 5) 100%pre-rigor trim O R. P. NUSBAUM 6 ) 100% post-rigor trim The post-rigor trim was a duplicate of the 0% frozenflaked formulation differing only in that the post-rigor sample came from the same animal as the pre-rigor Extension. Specialist, Department of Animal Science, Virginia Po1ytech)nic Institute and State University, Blacksburg, V A ~ Reciprocal Meat Conference Proceedings, Volume , 1979.

2 AMERICAN MEAT SCIENCE ASSOCIATION Cooking loss values of the frozen patties (Table 4) indicate a significant advantage for patties frozen at faster rates. Patties frozen at the 100 minute rate, over all formulations, averaged nearly a 25% weight loss during cooking. This was significantly higher than all other freezing rates. Results and Discussion Color reflectance values (Table 1) increased as percentage of frozen-flaked trim was increased, with the 100%frozen-flaked formulation recording the highest value among all formulations and within each freezing rate. Slower freezing rates produced a darker d o r which is in agreement with Sebranek et al., (1978). This may be due to larger ice crystal size caused by slower freezing rates (Menz and Luyet, 1961). Cooking loss values by formulation (Table 4) are TABLE 2 Freezing shrink values shown in Table 2 indicate no differences among the six formulations, however, freezing rate had a significant effect on freezing shrink. The superiority of faster freezing rates in reducing evaporation is clearly evident and substantial. Ei I n d i v i d u a l c e l l means and t r e a ment means' f o r f r e e z i n g s h r i n k percentage Freezing rates (Time f o r t5"c to -5'C chanqej 30 min. 80 min. 100 min. 6 min. Formulation Water holding capacity (WHC) of the six pattie formulations was measured prior to freezing (Table 3 ). W H C increased significantly with greater proportions of frozen-flaked trim as evidenced by IOWW ratios. This was particularly evident when comparing the 100% frozen-flaked pattie to those having no frozen-flaked trim. Flaking apparently increases W H C in a similar fashion t o grinding (Hamm, 1959, 1977) by exposing more polar groups for binding with water molecules. Pre-rigor patties also showed greater W H C than post-rigor patties (Table 3 ) and is attributed to the higher p H of the pre-rigor meat (Hamm, 1960; McCl'iin and hlullins, 1969). means 0% Frazen t r i m d " 20% Frozen t r i m a 50% Frozen t r i m a 100% Frozen t r i m Prerigor t r i m a Postrigor t r i m Za means 0.53d 1.61' 2.9gb 4.65a 'Treatment means i n a column o r r o w w i t h t h e same s u p e r s c r i p t s a r e 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 (~4.05). 'Calculated u e i g h t loss as a percentage o f i n i t i a l p a t t i e u e i g h t. TABLE 1 Individual c e l l means and means1 f o r color reflectance values' Fo rmul a t i on Freezing r a t e s (Time f o r +5"C t o -5 C change) mea n s 6 min. 30 min. 80 min. 100 m i n. 0% Frozen trim Unfrozen s c 20% Frozen trim ' 50% Frozen trim OO 34.OO b 100% Frozen trim oo a Prerigor trim e Po s t r i go r tr i m d y e mea n s 23.23' 34.40a 34.06a 28.33b 21.76d 'Treatment means i n a column o r row w i t h the same superscripts a r e not s i g n i f j c a n t l y d i f f e r e n t (p<0.05). *Larger values i n d i c a t e l i g h t e r c o l o r s

3 AMERICAN MEAT SCIENCE ASSOCIATION not greatly different cxcept for the 100%frozen-flaked pre-rigor patties. I3oth formulations had signifiloss which indicate the ability of cantly l o ~ cooking r these pittics to preserve their high WHC during a very rapid thaw (grilling at C). These differenccs continued to exist regardless of whether the patties mere cookcd beforc freezing, from the frozen statr or after thawing as shown in Table 5. TABLE 3 iiiitl Means1 for water holding capacity2 patties before freezing. Water Holding capacity Formulation ~~ of W l i c ~ 1all pattie formulations were evaluated for flavor, tenderness, juiciness and overall acceptability, only tenderness showed notable differences ( Table 6 ). Values iiidicate that tenderness decreases with prolonged freezing times and increases somewhat with higher proportions of frozen-flaked trim. ~ 0% Frozen trim 2.81a 20% Frozen trim 2. 27b 50% Frozen trim 2. 06b C 100% Frozen trim 1.76 Prerigor trim 2.13b Postrigor trim 2. 75a A mechanical measurement of tenderness (the Warner-Bratzler shearing device) showed the same results ( Table 7 ) but differentiates between formulations a little mcire distinctly. Low shear values such as 0.58 are actually undesirably tender being described by panelists as mush) or mealy. These data suggest that ~ h i kflaked levels of up to 50% may be acceptable to consumers, increased levels beyond this p i n t may sacrifice some qiiality and should be used with cautio 11, Treatment means i n a column w i t h the same suverscripts are not significantly different (p<o.o5). 2Using press method and expressed as a ratio of total moisture area/meat area. Higher value indicates 1ower WHC. Except for taste panel tcnderness values (Table 6 ) : pre-rigor patties were not significantly cliff erent from TABLE 4 Individual c e l l means and means f o r percentage cooking loss Formulation 2 Freezinq r a t e s (Time f o r +5 C-to -5 C change) means 6 min. 30 min. 80 min. 0% Frozen trim Unfrozen m i n % Frozen trim a 50% Frozen trim a 100% Frozen trim b Preri gor t r i m Pos tr i gor t r i rn a d 19.22d ~ 24.37a mea n s 22.88a - Treatment means i n a column o r row w i t h the same superscripts a r e not s i g n i f i c a n t l y d i f f e r e n t (p<0.05). 2Calculated weight l o s s a s a percentage of precooked p a t t i e weight. -25-

4 AMERICAN MEAT SCIENCE ASSOCIATION post-rigor patties for any of the other sensory traits evaluated. This would indicate that pre-rigor meat, when processed under proper conditions, can be utilized successfully in the production of frozen, g r o m d beef patties. Shear values shown in Table 7 clearly indicate that slower freezing rates decrease, pattie tcnderness and are in agreement with results reported by nmnerous investigators ( Hankins and Hiner, 1940; Hiner ant1 Hankins, 1946; Guenther a n d Hcmkkson, 1962; Sebranek et al., 1978). As additional evidence, the subjective taste panel score for texture at the 100 minute rate (5.54, Table 6 ) was significantly lower than those scores at the three faster freezing ratc,s. Neither the Warner-Bratzler shear nor taste panel c d u a t i o n could detect tenderness differenccs between unfrozen patties and those frozen at the 6-minute rate. This suggests that freezing at this rapid rate does not adversely affect product tenderness. Microstructure evaluations were made to determine, which freezing rate might be critical to structural integrity of the pattie which in turn influences tcxture, tenderness and eating quality. LJI and cor1-esponding SEM micrographs of the unfrozen 0, 20, 50 and 100% frozen-flaked formulations are shown in Figures 1 and 2. Unfrozen pre-rigor and post-rigor patties resulted in microstructural appearance essentially the same as the unfrozen 0%frozen-fla 1 or all-fresh p i t ties and are not shown here. The comniinution effect of flaking is clearly apparent when comparing 0% frozen-flaked formulatioki ( Figurvs 1 a i d 2, A ) with 1CO5%frozen-flake3 patties (Figures 1 and 2, D ). Intact rquscle fibs, nuclei and distinct fat globules arc' readily visible at the zero and 2C% levels. As the percc.ntage of frozen-flaked trim increases, muscle filxrs and fat globules lose individual integrity and lxcoine homogenous in nature. LM comparisons of freczing rate effect on each pattie formulation are shown in Figures 3-7. Figures 8-12 show the same samples froin SEM. The obvious i n c r a s e in ice crystal cavity size from the 6-minute to the 100-minute rate is quite evident for each formulation (-4-D for Figures 3-12). It is, indeed, apparent that slower rates of freezing result in much larger ice crystals which cause muscle fibers, nirclci a n d fat globules to be clumped together. Thesc micrographs illiistrate the suggcasted freezing concepts reported by Jloran ( 1932), Koonz and Ramsbottom (19i39). Hiner et (11. ( 1945), Meryinan (1956) and Love ( 1966). Several exaniples of the unidirectional dwelopment of ice crystals described by Menz and Luvet (1961) in intact musclcl are also apparent i n several of the SEN micrographs of these ground beef patties (Figure 8 A and Figure 9 A ). The significantly greater cooking loss expericmced with slower freezing rates (Table 4 ) inny lie directly attributed to the larger ice crystal size. Larger crystals, rc~sultingfrom slower freezing rates, have (le- TABLE Cooking variable 1 The e f f e c t o f f o r m u l a t i o n o n percentage c o o k i n g l o s s ' cooked nonfrozen, f r o z e n and a f t e r t h a w i n g from p a t t i e s - Formul a t i o n 0% Frozen trim 20 % Frozen trim 50% Frozen trim 100% Frozen trim Prerigor trim Postrigor means Cooked f r o m unfrozen s t a t e a Cooked f r o m frozen state a Cooked a f t e r thawing t o 5 C b means a 22.20a 20.83a 16.66' 15.14' 21.44a trim ' T r e a t m e n t means i n a column o r row w i t h t h e same s u p e r s c r i p t s a r e 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 (p<o.o5). 'Calculated w e i g h t loss a s a percentage o f precooked p a t t i e w e i g h t

5 AMERICAN MEAT SCIENCE ASSOCIATION TABLE 6 Individual c e l l means and means 1 f o r sensory evaluation o f tenderness 2 ~~ Formul a t i on Freezi ng r a t e s (Time f o r +5"C t o -5 C change) Un- 100 m i n. means frozen 6 min. 30 m i n. 80 min. 0% Frozen trim OO 5.oo 6. OOb ' 20% Frozen t r i m 7.OO OO ayb 50% Frozen trim a 100% Frozen trim a Prerigor trim ' P o s t r i g o r trim ayb means 6.33a'b 6.74a 6.45a'b 6.04b 5. 54c 'Treatment means i n a column o r row with the same s u p e r s c r i p t s a r e not s i g n i f i c a n t l y different ( ~ ~ ). 2Based on hedonic s c a l e : 9 = extremely tender; 1 = extremely tough. Individual c e l l means and means Formulation Un- 1 f o r Warner-Bratzl er shear values ( k g s ) 2 Freezi ng r a t e s (Time f o r +5"C t o -5 C change) means frozen min m i n m i n m i n % Frozen trim b 50% Frozen trim O f ,58d P r e r i gor trim ay P o s t r i g o r trim a3b 1.14' 1. l l C 1.25b 1.30b 1.36a 0% Frozen trim 100% Frozen trim ' ' means 'Treatment means i n a column o r row with the same s u p e r s c r i p t s a r e not s i g n i f i c a n t l y d i f f e r e n t (p<o.05) 'Smaller values i n d i c a t e l e s s r e s i s t a n c e t o the shear f o r c e a

6 " \I I AMERICAN MEAT SCIENCE ASSOCIATION I -28 -

7 AMERICAN MEAT SCIENCE ASSOCIATION

8 AMERICAN MEAT SCIENCE ASSOCIATION m -30-

9 AMERICAN MEAT SCI ENCE ASSOC I AT ION -31 -

10 AMERICAN MEAT SCIENCE ASSOCIATION -32-

11 AMERICAN MEAT SCIENCE ASSOCIATION al c e - 0 N x -333-

12 AMERICAN MEAT SCIENCE ASSOCIATION -34-

13 AMERICAN MEAT SCIENCE ASSOCIATION a, c?! x.. E._ c L Y O +O +- ou -35-

14 AMERICAN MEAT SCIENCE ASSOCIATION

15 AMERICAN MEAT SCIENCE ASSOCIATION.-C E \o a, + e i'._ L t In- 0 c

16 AMERICAN MEAT SCIENCE ASSOCIATION -338-

17 AMERICAN MEAT SCIENCE ASSOCIATION -39-

18 AMERICAN MEAT SCIENCE ASSOCIATION creased surface area in contact with pattie tissue than the numerous, smaller ice crystals formed in rapid freezing. It appears that during rapid thawing (cooking), water produced from the larger crystals does not have time to migrate back to binding sites which were dehydrated during slow freezing. Ultimately, this water is more readily lost during cooking. Also, greater moisture loss during ccoking may result in increased protein denaturation which would reduce tenderness. Both objective and subjective measurementc; cf pattie tenderness (Tables 6 and 7 ) rccorded significantly lower scores at the slowest freezing rate. Micrographs also indicate that freezing rate differences became less detectable but were still apparent as greater amounts of frozen trim were used in th? pattie formulation. This is particularly c~vident for the 50 and 100%frozen-flaked formulations ( Figures 10 and 11). Summary It is apparent that structural changcs arc' minimized liy faster freezing rates for ground muscle. Change is gradual with time rather than occurring at any one freezing rate. Structural change in turn influences the freezing shrink and cooking loss cxpvrienced by the patties. Freezing rates of up to 80 minutes can be utilized before quality changes are readily detectable. However, faster freezing rates significantly reduce freezcr shrink and should be utilized when economically feasible. Frozen-flaked trim in pattie formulations causes some structural change in the patties which is not readily detectable until 50% or more of thcl formulations contains the frozen product. Then texture and -40- tentlerncss fiecomes noticmhly changed antl adverse- ly affects pattie quality. Finally. pre-rigor trim, when processed cor1rctly, compare5 verjz facorably n itli conventionally 1)rocessed product m t l offer\ potential time, \pace aiid ellergy savings REFERENCES Boyd, A Pros and cons of critical point drying and freeze drying for SEJ'I. Scanning Electron Microscopy 2:303. Guenther, J. J. and R. L. Henrickson Temperatures, methods used iii freezing determine tendelmess, color of meat. Quick Frozen Foods 25:115. Hamtn, R Biochemistry of meat hydration. Am. Meat Inst. Found. Res. Conf. Proc. 11:17. Hamm, R Biochemistry of meat hydration. Adv. Food Res. 10:355. Hamni, R Postmortem breakdown of A T P and gly cogen in ground muscle: A review. Meat Sci. 1:15. Hankins, 0. G. and R. L. Hiner Freezing makes beef tenderer. Food Ind. 12:49. Hiner, R. L. and 0. G. Hankins Fiber splitting results in more tender beef. Quick Frozen Foods 8:115. Hiner, R. L., L. L. Madsen and 0. G. Hankins Histological characteristics, tenderness, and drip losses of beef in relation t o temperature of freezing. Food Res. 10:312. Koonz, C. H. and J. M. Ramsbottom A method foi. studying the histological structure of frozen products. I. Poultry. Food Res. 4:117. Love, R. M The freezing of animal tissue. Pages in H. T. Meryman, ed. Cryobiology. Academic Press, New York. McClain, P. E. and A. M. Mullins Relationship of water-binding capacity and p H to tendemess of bovine muscle. J. Anim. Sei. 29 ( 2 ) :268. Menz, L. J. and B. J. Luyet An electron microscope study of the distribution of ice in single muscle fibers frozen rapidly. Biodynaniica 8 :261. Meryman, H. T Mechanics of freezing in living cells and tissues. Science 124:515. Moran, T Rapid freezing. Critical r a t e of cooling. J. Soc. Chetn. Ind. 51:16T. Sebranek, J. G., P. N. Sang, R. E. Rust, D. G. Topel, and A. A. Kraft Influence of liquid nitrogen. liquid carbon dioxide and mechanical freezing on sensory properties of ground beef patties. J. Food Sei. 43:842. Wang, H., E. Auerbach, V. Bates, D. M. Doty antl H. R. Kraybill A histological and histochemical s t u d y of beef dehydration. Food Res. 19:543.