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Comparison of sensory characteristics and fatty acid composition between Wagyu crossbred and Angus steers
Meat Science 35 (1993) 289-298
Comparison of Sensory Characteristics and Fatty Acid Composition Between Wagyn Crossbred and Angus Steers S. G. May, C. A. Sturdivant, D. K. Lunt, R. K. Miller & S. B. Smith* Department of Animal Science, Texas Agricultural Experiment Station, Texas A&M University, College Station, TX 77843, USA (Received 23 April 1992; revised version received 30 September 1992; accepted 4 October 1992)
ABSTRACT Angus (n = 10) and crossbred (3/4 and 7/8) Wagyu (n = 10) steers were fed a diet according to typical Japanese standards for 552 days. The steers were fed to gain approximately 0.90 kg/head/day. Fatty acid composition was determined for subcutaneous and intramuscular adipose tissue, and M. longissimus dorsi muscle. Trained sensory evaluation and a consumer triangle test were performed on M. longissimus dorsi muscle steaks. For subcutaneous and intramuscular tissue. Wagyu adipose tissue possessed higher (P < 0.05) percentages of 14: 1, 16:1 and 18:1 and a lower (P < 0.05) percentage of 16:0 and 18:0 than corresponding tissues from Angus steers. Trained sensory panel analysis revealedno differences ( P > 0.05) in any of the sensory traits between steaks from Wagyu crossbred and Angus steers. However, a consumer triangle test indicated that consumers can detect a difference between breeds.
INTRODUCTION Japanese Wagyu cattle are characterized by their genetic ability to marble and produce highly palatable beef (Yamazaki 1981). The Japanese utilize a unique m a n a g e m e n t p r o g r a m m e to obtain this high quality beef, which includes feeding the animals a ration high in roughage for long periods * To whom correspondence should be addressed. 289 Meat Science 0309-1740/93/$06.00 © 1993 Elsevier SciencePublishers Ltd, England. Printed in Great Britain
290
S. G. May, C A. Sturdivant, D. K. Lunt, R. K. Miller, S. B. Smith
of time. Fatty acid composition can be altered by diet (Westerling & Hedrick, 1979; Eichhorn et al., 1986) and breed (Eichhorn et al., 1986; Sturdivant et al., 1992), and these changes in fatty acid composition have been shown to influence beef palatability, particularly flavor (Dryden & Marchello, 1970); Westerling & Hedrick, 1979). Melton et al. (1982) showed a significant positive relationship between desirable flavor scores and the percentage of oleate in ground beef. Westerling and Hedrick (1979) indicated that sensory scores were positively associated with total unsaturated fatty acids. Subcutaneous adipose tissue from Japanese Black steers has been shown to possess over 48% oleate (Tanaka, 1985). Sturdivant et al. (1992) found monounsaturated:saturated fatty acid ratios as high as 2.57 for subcutaneous adipose tissue from Japanese Wagyu steers. While previous data suggest that the percentages of unsaturated fatty acids in Wagyu adipose tissue may be higher than those from other breeds, these comparisons have been made across studies and confounded by extrinsic factors. In order to accurately compare Wagyu beef to beef produced from typical US breed, management practices must be the same. The objective of this study was to compare fatty acid composition and sensory characteristics between crossbred Wagyu steers and Angus steers raised under identical management practices.
EXPERIMENTAL PROCEDURE Angus (n = 10) and crossbred (3/4 and 7/8) Wagyu (n = 10) steers with mean initial weights of 220 kg and 260 kg, respectively, were fed a diet according to typical Japanese standards for 552 days. The steers were fed to gain approximately 0.90 kg/head/day. In order to regulate weight gain, the diet was adjusted at 14-day intervals. The diet contained 25% roughage throughout the feeding period. The steers were transported to the Rosenthal Meat Science and Technology Center at Texas A&M University and were slaughtered conventionally. Carcass data for the steers showed no significant differences in physiological maturity (Angus = A91 and Wagyu = A87) or 12th rib fat thickness (Angus --- 3.30 cm and Wagyu = 3-71 cm). A more detailed description of the genetic profile of the animals and feeding protocol is given in Lunt et al. (1993).
Fatty acid analyses At the time of slaughter, a section of loin from the 2nd to 6th lumbar region was removed from the carcass for fatty acid analysis. The subcutaneous (SC) adipose tissue sample was removed dorsal to the 2nd
Fatty acid and sensory analysis of Wagyu and Angus beef
291
lumbar vertebra. Intramuscular (IM) adipose tissue samples were obtained by dissecting a 5.0-cm section of the M. longissimus dorsi (LD) from the loin section. After the physical dissection of the intramuscular adipose tissue, the remaining muscle was used as the LD samples. Samples of 100 mg and 1 g were used for total lipid extraction from adipose tissue and LD, respectively (Folch et aL, 1957). Fatty acids were determined following the procedures of Huerta-Leidenz et al. (1991). The methylation procedure used was a modification of the procedure of Morrison and Smith (1964). Fatty acid methyl esters were analyzed using a flame ionization gas chromatograph (Packard, Model 437A, Raritan, N J) equipped with a packed stainless steel column. At 8 min post-injection, the column temperature was increased from 180°C to 230°C at a rate of 10°C/min. The injection port and detector were at 250°C. The flow rates for the carrier gas (nitrogen), hydrogen and breathing air were 16, 34 and 214 ml/min, respectively. Peak areas were calculated with a computing integrator. Identification of the fatty acid methyl esters was determined by running reference standards of known methyl esters (Nu-Chek Prep, Inc., Elysian, MN). The internal standard used to quantify the fatty acids was C-l 2 fatty acid methyl ester.
Sensory analyses After carcasses were chilled for 24 h, boneless ribeye rolls were removed from the left sides of each carcass, fabricated into 2.54-cm steaks and used for sensory evaluation. Beginning at the anterior end of the ribeye roll, the first steak was trimmed of all external fat and connective tissue and was used to determine the percentage ether extractable fat and percentage moisture (AOAC, 1984). Subsequent steaks (two and three) were used for trained sensory evaluation and Warner-Bratzler shear force determination, respectively. In order to assess the ability of consumers to detect differences between steaks from Angus and Wagyu crossbred steers, steaks four, five and six were used for a consumer triangle test (Meilgaard et al., 1987). All steaks were broiled to an internal temperature of 70°C on Farberware Open Hearth electric broilers. Cooking time and weights were recorded before and after cooking and percentage cooking loss was calculated. A six-member trained sensory panel was used to evaluate 1.27-cm cubes from each steak (AMSA, 1978). Samples were evaluated for juiciness, flavor intensity, muscle fiber tenderness, overall tenderness, and connected tissue amount on an eight-point scale (8 -- extremely juicy, intense, tender, no perceivable connective tissue; 1 -- extremely dry, bland, tough, and abundant connective tissue). After cooking, steaks
292
S. G. May, C. A. Sturdivant, D. K. Lunt, R. K. Miller, S. B. Smith
were allowed to cool to room temperature and eight 1.27-cm cores were removed from each steak parallel to the direction of the muscle fibers. The cores were sheared using a Warner-Bratzler shear device. A triangle test was conducted to determine whether consumers (n = 90) could detect differences between steaks from Wagyu and Angus steers. The steaks were coded and randomized within animal and breed. Each panelist was presented with three coded samples with two 'like' samples from a steak from one breed and one sample from the other breed. The panelists were asked to determine which sample was different based on eating quality (tenderness, juiciness, and flavor). Therefore, with totally random selection, each panelist would have a one-in-three chance of selecting the correct response. Panelists evaluated two sample combinations: (1) one Angus and two Wagyu, and (2) two Angus and one Wagyu, for a total of 180 tests. Further, the panelists were asked to indicate in qualitative terms (tenderness, juiciness, flavor, or other) the reason for their decision and the level of difference that they though existed between the two products.
Statistical analyses Analysis of variance was conducted to examine the effect of breed (SAS, 1986). Mean separations were performed using the StudentNewman-Keul procedure (Steel & Torri, 1980). For the consumer triangle test, the number of correct responses was determined and analyzed according to Meilgaard et al. (1987).
RESULTS A N D DISCUSSION
Fatty acid analyses For SC and IM adipose tissue, Wagyu steers had higher (P < 0.05) percentages of 16:1 and 18:1 and lower (P < 0.05) percentages of 16:0 and 18:0 than tissue from Angus steers (Table 1). Huerta-Ledidenz et al. (1993) reported higher percentages of 14: 1, 16: 1, and 18:1 in SC adipose tissue from Bos indicus cows when compared to adipose tissue from Bos taurus cows. In a study where diet was held constant, Gillis and Eskin (1973) compared six crossbreeds of cattle and found differences in 14:0, 16:1 and 18:0 in SC and IM adipose tissue. Gillis and Eskin (1973) concluded that genetically influenced variation in physiological growth may cause variation in fatty acid composition. Link et al. (1970) examined fatty acid composition of bovine subcutaneous adipose tissue
Fatty acid and sensory analysis of Wagyu and Angus beef
293
TABLE 1 M a j o r F a t t y Acid C o m p o s i t i o n (%) for A n g u s and C r o s s b r e d Wagyu Steers by Tissue Sitea
Fatty acid
Angus
Wagyu
SE
3.18 1.51 30.15 d 5-50 C 11.33 d 45.17 ~ 2.19 1.17 e
3.19 1.80 26.68 c 6.34 d 9.02" 50.20 d 2.06 1.50 d
0.23 0.15 0-81 0.39 0-61 1-19 0.14 0-06
2.88 1.11 30.16 d 3.76 C 13.81 d 44.81" 2.04 1-10 c
2.99 1.31 26.89 c 4.79 d 10.83" 50.25 d 2.02 1.38 d
0.22 0.17 0.77 0-43 0-82 1.19 0.15 0.06
2.25 ~ 0.91 ~ 31-70 4.24 c 11-56 d 44.15 4.16 1.08 ~
3-10d 1-35 d 32-01 5.54 d 8.98" 45.22 3.23 1.17 d
0-21 0.12 0.70 0.29 0.43 0.88 0.55 0.03
Subcutaneous 14:0 14:1 16 : 0 16 : 1 18 : 0 18 : 1 18:2 MUFA/SFA b
Intramuscular 14 : 0 14:1 16:0 16 : 1 18 : 0 18 : 1 18:2 MUFA/SFA b
M. longissimus dorsi 14:0 14:1 16 : 0 16 : 0 18 : 0 18 : 1 18 : 2 MUFA/SFA b
o Percentage of the total peak area of the fatty acids listed. b S F A = saturated fatty acids ( 1 4 : 0 , 16:0, 18:0); M U F A = unsaturated fatty acids ( 1 4 : 1 , 16:1, 18:1). cd M e a n s with different superscripts within the same row differ significantly ( P < 0.05).
at different stages of growth, and concluded that increased fatness and/or age altered the proportions of fatty acids in the tissue. Leat (1975) found a greater proportion of unsaturated fatty acids with increased fatness. Even though no significant differences occurred between breeds, Wagyu crossbred carcasses tended to have more fat at the 12th rib and higher marbling scores than Angus carcasses (Lunt et al., 1993). Differences (P < 0.05) did occur for ether extractable fat from the rib eye muscle
294
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with 18.9% for the Wagyu crossbred steers and 14.5% for the Angus steers (Lunt et al., 1993). Yamazaki (1981) demonstrated a high propensity for Japanese Black (Wagyu) steers to deposit intramuscular adipose tissue. While the differences found in the present study may be, in part, related to fatness, with identical management protocol and similar physiological age, it is conceivable that these differences were genetically linked. Tanaka (1985), in a comparison of Japanese breeds, demonstrated a higher percentage of oleate (18:1) and lower percentage of palmitate (16:0) in the SC adipose tissue of Japanese Black steers as compared to Japanese Shorthorn or Holstein steers. While our differences were not as extreme as those reported by Tanaka (1985), in both SC and IM, oleate was the unsaturated fatty acid which possessed the greatest numerical difference between breeds, while palmitate exhibited the largest difference in the saturated fatty acids (Table 1). Tanaka (1985) reported a higher unsaturated to saturated ratio for SC adipose tissue from Japanese Black steers than that from Holstein or Shorthorn steers. For all tissue types in the present study, the differences in the percentage fatty acids resulted in a significant difference in the monounsaturated:saturated fatty acid ratios (MUFA/SFA) between breeds (Table 1). In an experiment comparing the fatty acid composition of SC from purebred Japanese Wagyu cattle differing in Japanese Fat Quality Grade, the MUFA/SFA ranged from 2-08 to 2.57 (Sturdivant et al., 1992), which was higher than the values observed in this study. Our results were similar to those from another study in this laboratory which examined the fatty acid composition of Wagyu crossbred cattle fed a high concentrate corn-based diet (Sturdivant et al., 1992). That study reported MUFA/SFA ratios ranging from 1.46 for SC to 1-19 for LD. This is comparable to the results for the Wagyu crossbred steers in this study, with ratios of 1.50, 1.38, and 1.17 for SC, IM and LD, respectively. Because the cattle in the two studies were genetically similar, but were on dramatically different feeding regimens (high-concentrated versus restricted gain/high roughage), the data suggest that the higher MUFA/SFA ratios may be more genetically determined than environmentally influenced.
Sensory analyses Trained sensory evaluation and shear force measurements showed no differences (P > 0.05) for any of the palatability traits (Table 2). The shear force values for both breed types were similar to values reported by Japanese researchers in studies of meat from Japanese Black steers
Fatty acid and sensory analysis of Wagyu and Angus beef
295
TABLE 2 Means (and Standard Deviations) for Palatability Traits for Steaks from Each Breed Type
Trait n Juiciness ab Flavor intensity" Connective tissue a Myofibrillar tenderness a Overall tenderness a Shear force (kg) Cooking toss (%) Cooking rate (min)
Angus
Wagyu
10 6-13 (0.75) 5.87 (0.73) 6.73 (0.90) 6.30 (0.83) 6.27 (0,86) 3-50 (0.44) 17.81 (3.12) 20.19 (3.33)
10 6.11 (0.78) 5.87 (0.79) 6.90 (0.88) 6.48 (0.79) 6.48 (0.79) 3.67 (0.59) 18.79 (3.46) 20.88 (4.55)
1 -- Extremely dry, extremely bland, extremely difficult, abundant, extremely tough; 8 -- extremely juicy, extremely intense, extremely easy, no perceivable, extremely tender. b Means within the same row are not significantly different (P > 0.05).
(Yamazaki, 1981; Mitsumoto et al., 1986). Past studies have demonstrated variation in aspects of palatability, particularly tenderness across breeds (Peacock et al., 1982; Wheeler et al., 1990). Standard deviations tended to be similar between breed types for each sensory trait. Previous studies have indicated that changes in the fatty acid composition of meat affect palatability, with flavor being the attribute most influenced (Dryden & Marchello, 1970; Westerling & Hedrick, 1979; Melton et al., 1982). These studies found a positive relationship between oleate concentration and flavor scores. With the differences in fatty acid composition and the niche in the consumer beef market this product would target, it was important to examine the consumer reaction to Wagyu beef. The consumer triangle test indicated that the consumers could detect differences between steaks from Wagyu crossbred and Angus steers (Table 3). Of the 180 responses, there were 98 correct responses. This level of correct responses indicated that at a 99.5% TABLE 3 Consumer Triangle Test Comparison between Steaks from Wagyu Crossbred and Angus Steers
Test comparison 2 Wagyu vs 1 Angus 2 Angus vs 1 Wagyu Total number of correct responses
Correct responses 51 of 90 47 of 90 98 of 180
296
S. G. May, C. A. Sturdivant, D. K. Lunt, R. K. Miller, S. B. Smith
50 .2.1
40 ~e
20 trl
10 0
SLIGHT
MODERATE MUCH MAGNITUDEOF THE DIFFERENCE
EXTREME
Magnitude of the differencebetween samples for the correct responses (n = 98).
Fig. 1.
confidence interval, 47-5% of the consumers could detect a difference in eating quality between steaks from Wagyu crossbred and Angus steers (random selection of samples would have resulted in one-third of the consumers detecting a difference). It is important to note that this test does not indicate which sample(s) the consumers actually preferred. The consumer panel indicated that the degree of difference was primarily 'slight' to 'moderate' with 76% of the correct responses in these two categories (Fig. 1). The major qualitative traits used to describe differv~ p.i 30 Z
20-
~
~
tO'
0'" Flavor Tenderness Juiciness
F&T
F&J
T&J
F,T&J
Fatty
QUALITATIVEDESCRIPTION Fig. 2.
Q u a l i t a t i v e d e s c r i p t o r s as a s s e s s e d b y the c o n s u m e r s w i t h correct r e s p o n s e s .
Fatty acid and sensory analysis of Wagyu and Angus beef
297
ences in eating quality were tenderness, juiciness and flavor. When the consumers were asked to indicate which trait(s) they used to determine the difference between samples, the majority of the correct respondents used a combination of tenderness and juiciness, while other consumers indicated the singular traits of tenderness and flavor (Fig. 1). Three percent of the panelists utilized a descriptor other than those commonly associated with eating quality (tenderness, juiciness and flavor). These panelists utilized 'fatty' as the descriptor. This may not be surprising with Wagyu crossbred steers having an average of 4.4% more ether extractable fat from the rib eye muscle than Angus steers (Lunt et al., 1993). In summary, differences in fatty acid composition existed between Wagyu crossbred and Angus steers fed identically, the most notable differences (P < 0.05) being a higher percentage of oleate and lower percentage of palmitate in SC and IM of Wagyu crossbred steers. Although both breeds produced high quality steaks, consumers could detect differences between breeds. ACKNOWLEDGEMENT Technical article 30921 from the Texas Agricultural Experiment Station. REFERENCES AMSA (1978). Guidelines for Cookery and Sensory Evaluation of Meat. American Meat Science Association, Chicago, IL. AOAC (1984). Official Methods of Analysis. Association of Official Analytical Chemists, Washington, DC. Dryden, F. D. & Marchello, J. A. (1970). J. Anim. Sci., 31, 36. Eichhorn, J. M., Coleman, L. J., Wakayama, E. J., Blomquist, G. J., Bailey, C. M. & Jenkins, T. G. (1986). J. Anita. Sci., 63, 781. Folch, J., Lees, M. & Stanley, G. H. S. (1957). J. Biol. Chem., 226, 497. Gillis, A. T. & Eskin, N. A. M. (1973). J. Food Sci., 38, 408. Huerta-Leidenz, N. O., Cross, H. R., Savell, J. W., Lunt, D .K., Baker, J. F., Pelton, L. S. & Smith, S. B. (1991). J. Anim. Sci., 69, 3665. Huerta-Leidenz, N. O., Cross, H. R., Savell, J. W., Lunt, D. K., Baker, J. F., Pelton, L. S. & Smith, S. B. (1993). J. Anim. Sci. 71,625. Leat, W. M. F. (1975). J. Agric. Sci., Camb., 85, 551. Link, B. A., Bray, R. W., Cassens, R. G. & Kauffman, R. G. (1970). J. Anim. Sci., 30, 722. Lunt, D. K., Riley, R. R. & Smith, S. B. (1993). Meat Sci., (accepted). Meilgaard, M., Civille, G. V. & Carr, B. T. (1987). Difference tests. In Sensory Evaluation Techniques, CRC Press, Boca Raton, FL. Melton, S. L., Amiri, M., Davis, G. W. & Backus, W. R. (1982). J. Anim. Sci., 55, 77.
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Mitsumoto, M., Yamashita, Y., Mitsuhashi, T. & Nakanishi, N. (1986). Jpn. J. Zootech Sci., 57, 257. Morrison, W. R. & Smith, L. M. (1964). J. Lipid Res., 5, 600. Peacock, F. M., Kroger, M., Palmer, A. Z., Carpenter, J. W. & Olson, T. A. (1982). J. Anita. Sci., 55, 797. SAS (1986). S A S User's Guide: Statistics. SAS Institute, Inc., Cary, CN. Steel, R. G. D. & Torrie, J. H. (1980). Principles and Procedures of Statistics: A Biometrical Approach, 2nd edn, McGraw-Hill, New York. Sturdivant, C. A., Lunt, D. K., Smith, G. C. & Smith, S. B. (1992). Meat Sci., 32, 449. Tanaka, S. (1985). Jap. J. Dairy & Food Sci., 34, 92. Westerling, D. B. & Hedrick, H. B. (1979). J. Anita. Sci., 48, 1343. Wheeler, T. L., Savell, J. W., Cross, H. R., Lunt, D. K. & Smith, S. B. (1990). J. Anita. Sci., 68, 3677. Yamazaki, T. (1981). Bull. Natl. Grassl. Res. Inst., 18, 69.
Comparison of Sensory Characteristics and Fatty Acid Composition Between Wagyn Crossbred and Angus Steers S. G. May, C. A. Sturdivant, D. K. Lunt, R. K. Miller & S. B. Smith* Department of Animal Science, Texas Agricultural Experiment Station, Texas A&M University, College Station, TX 77843, USA (Received 23 April 1992; revised version received 30 September 1992; accepted 4 October 1992)
ABSTRACT Angus (n = 10) and crossbred (3/4 and 7/8) Wagyu (n = 10) steers were fed a diet according to typical Japanese standards for 552 days. The steers were fed to gain approximately 0.90 kg/head/day. Fatty acid composition was determined for subcutaneous and intramuscular adipose tissue, and M. longissimus dorsi muscle. Trained sensory evaluation and a consumer triangle test were performed on M. longissimus dorsi muscle steaks. For subcutaneous and intramuscular tissue. Wagyu adipose tissue possessed higher (P < 0.05) percentages of 14: 1, 16:1 and 18:1 and a lower (P < 0.05) percentage of 16:0 and 18:0 than corresponding tissues from Angus steers. Trained sensory panel analysis revealedno differences ( P > 0.05) in any of the sensory traits between steaks from Wagyu crossbred and Angus steers. However, a consumer triangle test indicated that consumers can detect a difference between breeds.
INTRODUCTION Japanese Wagyu cattle are characterized by their genetic ability to marble and produce highly palatable beef (Yamazaki 1981). The Japanese utilize a unique m a n a g e m e n t p r o g r a m m e to obtain this high quality beef, which includes feeding the animals a ration high in roughage for long periods * To whom correspondence should be addressed. 289 Meat Science 0309-1740/93/$06.00 © 1993 Elsevier SciencePublishers Ltd, England. Printed in Great Britain
290
S. G. May, C A. Sturdivant, D. K. Lunt, R. K. Miller, S. B. Smith
of time. Fatty acid composition can be altered by diet (Westerling & Hedrick, 1979; Eichhorn et al., 1986) and breed (Eichhorn et al., 1986; Sturdivant et al., 1992), and these changes in fatty acid composition have been shown to influence beef palatability, particularly flavor (Dryden & Marchello, 1970); Westerling & Hedrick, 1979). Melton et al. (1982) showed a significant positive relationship between desirable flavor scores and the percentage of oleate in ground beef. Westerling and Hedrick (1979) indicated that sensory scores were positively associated with total unsaturated fatty acids. Subcutaneous adipose tissue from Japanese Black steers has been shown to possess over 48% oleate (Tanaka, 1985). Sturdivant et al. (1992) found monounsaturated:saturated fatty acid ratios as high as 2.57 for subcutaneous adipose tissue from Japanese Wagyu steers. While previous data suggest that the percentages of unsaturated fatty acids in Wagyu adipose tissue may be higher than those from other breeds, these comparisons have been made across studies and confounded by extrinsic factors. In order to accurately compare Wagyu beef to beef produced from typical US breed, management practices must be the same. The objective of this study was to compare fatty acid composition and sensory characteristics between crossbred Wagyu steers and Angus steers raised under identical management practices.
EXPERIMENTAL PROCEDURE Angus (n = 10) and crossbred (3/4 and 7/8) Wagyu (n = 10) steers with mean initial weights of 220 kg and 260 kg, respectively, were fed a diet according to typical Japanese standards for 552 days. The steers were fed to gain approximately 0.90 kg/head/day. In order to regulate weight gain, the diet was adjusted at 14-day intervals. The diet contained 25% roughage throughout the feeding period. The steers were transported to the Rosenthal Meat Science and Technology Center at Texas A&M University and were slaughtered conventionally. Carcass data for the steers showed no significant differences in physiological maturity (Angus = A91 and Wagyu = A87) or 12th rib fat thickness (Angus --- 3.30 cm and Wagyu = 3-71 cm). A more detailed description of the genetic profile of the animals and feeding protocol is given in Lunt et al. (1993).
Fatty acid analyses At the time of slaughter, a section of loin from the 2nd to 6th lumbar region was removed from the carcass for fatty acid analysis. The subcutaneous (SC) adipose tissue sample was removed dorsal to the 2nd
Fatty acid and sensory analysis of Wagyu and Angus beef
291
lumbar vertebra. Intramuscular (IM) adipose tissue samples were obtained by dissecting a 5.0-cm section of the M. longissimus dorsi (LD) from the loin section. After the physical dissection of the intramuscular adipose tissue, the remaining muscle was used as the LD samples. Samples of 100 mg and 1 g were used for total lipid extraction from adipose tissue and LD, respectively (Folch et aL, 1957). Fatty acids were determined following the procedures of Huerta-Leidenz et al. (1991). The methylation procedure used was a modification of the procedure of Morrison and Smith (1964). Fatty acid methyl esters were analyzed using a flame ionization gas chromatograph (Packard, Model 437A, Raritan, N J) equipped with a packed stainless steel column. At 8 min post-injection, the column temperature was increased from 180°C to 230°C at a rate of 10°C/min. The injection port and detector were at 250°C. The flow rates for the carrier gas (nitrogen), hydrogen and breathing air were 16, 34 and 214 ml/min, respectively. Peak areas were calculated with a computing integrator. Identification of the fatty acid methyl esters was determined by running reference standards of known methyl esters (Nu-Chek Prep, Inc., Elysian, MN). The internal standard used to quantify the fatty acids was C-l 2 fatty acid methyl ester.
Sensory analyses After carcasses were chilled for 24 h, boneless ribeye rolls were removed from the left sides of each carcass, fabricated into 2.54-cm steaks and used for sensory evaluation. Beginning at the anterior end of the ribeye roll, the first steak was trimmed of all external fat and connective tissue and was used to determine the percentage ether extractable fat and percentage moisture (AOAC, 1984). Subsequent steaks (two and three) were used for trained sensory evaluation and Warner-Bratzler shear force determination, respectively. In order to assess the ability of consumers to detect differences between steaks from Angus and Wagyu crossbred steers, steaks four, five and six were used for a consumer triangle test (Meilgaard et al., 1987). All steaks were broiled to an internal temperature of 70°C on Farberware Open Hearth electric broilers. Cooking time and weights were recorded before and after cooking and percentage cooking loss was calculated. A six-member trained sensory panel was used to evaluate 1.27-cm cubes from each steak (AMSA, 1978). Samples were evaluated for juiciness, flavor intensity, muscle fiber tenderness, overall tenderness, and connected tissue amount on an eight-point scale (8 -- extremely juicy, intense, tender, no perceivable connective tissue; 1 -- extremely dry, bland, tough, and abundant connective tissue). After cooking, steaks
292
S. G. May, C. A. Sturdivant, D. K. Lunt, R. K. Miller, S. B. Smith
were allowed to cool to room temperature and eight 1.27-cm cores were removed from each steak parallel to the direction of the muscle fibers. The cores were sheared using a Warner-Bratzler shear device. A triangle test was conducted to determine whether consumers (n = 90) could detect differences between steaks from Wagyu and Angus steers. The steaks were coded and randomized within animal and breed. Each panelist was presented with three coded samples with two 'like' samples from a steak from one breed and one sample from the other breed. The panelists were asked to determine which sample was different based on eating quality (tenderness, juiciness, and flavor). Therefore, with totally random selection, each panelist would have a one-in-three chance of selecting the correct response. Panelists evaluated two sample combinations: (1) one Angus and two Wagyu, and (2) two Angus and one Wagyu, for a total of 180 tests. Further, the panelists were asked to indicate in qualitative terms (tenderness, juiciness, flavor, or other) the reason for their decision and the level of difference that they though existed between the two products.
Statistical analyses Analysis of variance was conducted to examine the effect of breed (SAS, 1986). Mean separations were performed using the StudentNewman-Keul procedure (Steel & Torri, 1980). For the consumer triangle test, the number of correct responses was determined and analyzed according to Meilgaard et al. (1987).
RESULTS A N D DISCUSSION
Fatty acid analyses For SC and IM adipose tissue, Wagyu steers had higher (P < 0.05) percentages of 16:1 and 18:1 and lower (P < 0.05) percentages of 16:0 and 18:0 than tissue from Angus steers (Table 1). Huerta-Ledidenz et al. (1993) reported higher percentages of 14: 1, 16: 1, and 18:1 in SC adipose tissue from Bos indicus cows when compared to adipose tissue from Bos taurus cows. In a study where diet was held constant, Gillis and Eskin (1973) compared six crossbreeds of cattle and found differences in 14:0, 16:1 and 18:0 in SC and IM adipose tissue. Gillis and Eskin (1973) concluded that genetically influenced variation in physiological growth may cause variation in fatty acid composition. Link et al. (1970) examined fatty acid composition of bovine subcutaneous adipose tissue
Fatty acid and sensory analysis of Wagyu and Angus beef
293
TABLE 1 M a j o r F a t t y Acid C o m p o s i t i o n (%) for A n g u s and C r o s s b r e d Wagyu Steers by Tissue Sitea
Fatty acid
Angus
Wagyu
SE
3.18 1.51 30.15 d 5-50 C 11.33 d 45.17 ~ 2.19 1.17 e
3.19 1.80 26.68 c 6.34 d 9.02" 50.20 d 2.06 1.50 d
0.23 0.15 0-81 0.39 0-61 1-19 0.14 0-06
2.88 1.11 30.16 d 3.76 C 13.81 d 44.81" 2.04 1-10 c
2.99 1.31 26.89 c 4.79 d 10.83" 50.25 d 2.02 1.38 d
0.22 0.17 0.77 0-43 0-82 1.19 0.15 0.06
2.25 ~ 0.91 ~ 31-70 4.24 c 11-56 d 44.15 4.16 1.08 ~
3-10d 1-35 d 32-01 5.54 d 8.98" 45.22 3.23 1.17 d
0-21 0.12 0.70 0.29 0.43 0.88 0.55 0.03
Subcutaneous 14:0 14:1 16 : 0 16 : 1 18 : 0 18 : 1 18:2 MUFA/SFA b
Intramuscular 14 : 0 14:1 16:0 16 : 1 18 : 0 18 : 1 18:2 MUFA/SFA b
M. longissimus dorsi 14:0 14:1 16 : 0 16 : 0 18 : 0 18 : 1 18 : 2 MUFA/SFA b
o Percentage of the total peak area of the fatty acids listed. b S F A = saturated fatty acids ( 1 4 : 0 , 16:0, 18:0); M U F A = unsaturated fatty acids ( 1 4 : 1 , 16:1, 18:1). cd M e a n s with different superscripts within the same row differ significantly ( P < 0.05).
at different stages of growth, and concluded that increased fatness and/or age altered the proportions of fatty acids in the tissue. Leat (1975) found a greater proportion of unsaturated fatty acids with increased fatness. Even though no significant differences occurred between breeds, Wagyu crossbred carcasses tended to have more fat at the 12th rib and higher marbling scores than Angus carcasses (Lunt et al., 1993). Differences (P < 0.05) did occur for ether extractable fat from the rib eye muscle
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with 18.9% for the Wagyu crossbred steers and 14.5% for the Angus steers (Lunt et al., 1993). Yamazaki (1981) demonstrated a high propensity for Japanese Black (Wagyu) steers to deposit intramuscular adipose tissue. While the differences found in the present study may be, in part, related to fatness, with identical management protocol and similar physiological age, it is conceivable that these differences were genetically linked. Tanaka (1985), in a comparison of Japanese breeds, demonstrated a higher percentage of oleate (18:1) and lower percentage of palmitate (16:0) in the SC adipose tissue of Japanese Black steers as compared to Japanese Shorthorn or Holstein steers. While our differences were not as extreme as those reported by Tanaka (1985), in both SC and IM, oleate was the unsaturated fatty acid which possessed the greatest numerical difference between breeds, while palmitate exhibited the largest difference in the saturated fatty acids (Table 1). Tanaka (1985) reported a higher unsaturated to saturated ratio for SC adipose tissue from Japanese Black steers than that from Holstein or Shorthorn steers. For all tissue types in the present study, the differences in the percentage fatty acids resulted in a significant difference in the monounsaturated:saturated fatty acid ratios (MUFA/SFA) between breeds (Table 1). In an experiment comparing the fatty acid composition of SC from purebred Japanese Wagyu cattle differing in Japanese Fat Quality Grade, the MUFA/SFA ranged from 2-08 to 2.57 (Sturdivant et al., 1992), which was higher than the values observed in this study. Our results were similar to those from another study in this laboratory which examined the fatty acid composition of Wagyu crossbred cattle fed a high concentrate corn-based diet (Sturdivant et al., 1992). That study reported MUFA/SFA ratios ranging from 1.46 for SC to 1-19 for LD. This is comparable to the results for the Wagyu crossbred steers in this study, with ratios of 1.50, 1.38, and 1.17 for SC, IM and LD, respectively. Because the cattle in the two studies were genetically similar, but were on dramatically different feeding regimens (high-concentrated versus restricted gain/high roughage), the data suggest that the higher MUFA/SFA ratios may be more genetically determined than environmentally influenced.
Sensory analyses Trained sensory evaluation and shear force measurements showed no differences (P > 0.05) for any of the palatability traits (Table 2). The shear force values for both breed types were similar to values reported by Japanese researchers in studies of meat from Japanese Black steers
Fatty acid and sensory analysis of Wagyu and Angus beef
295
TABLE 2 Means (and Standard Deviations) for Palatability Traits for Steaks from Each Breed Type
Trait n Juiciness ab Flavor intensity" Connective tissue a Myofibrillar tenderness a Overall tenderness a Shear force (kg) Cooking toss (%) Cooking rate (min)
Angus
Wagyu
10 6-13 (0.75) 5.87 (0.73) 6.73 (0.90) 6.30 (0.83) 6.27 (0,86) 3-50 (0.44) 17.81 (3.12) 20.19 (3.33)
10 6.11 (0.78) 5.87 (0.79) 6.90 (0.88) 6.48 (0.79) 6.48 (0.79) 3.67 (0.59) 18.79 (3.46) 20.88 (4.55)
1 -- Extremely dry, extremely bland, extremely difficult, abundant, extremely tough; 8 -- extremely juicy, extremely intense, extremely easy, no perceivable, extremely tender. b Means within the same row are not significantly different (P > 0.05).
(Yamazaki, 1981; Mitsumoto et al., 1986). Past studies have demonstrated variation in aspects of palatability, particularly tenderness across breeds (Peacock et al., 1982; Wheeler et al., 1990). Standard deviations tended to be similar between breed types for each sensory trait. Previous studies have indicated that changes in the fatty acid composition of meat affect palatability, with flavor being the attribute most influenced (Dryden & Marchello, 1970; Westerling & Hedrick, 1979; Melton et al., 1982). These studies found a positive relationship between oleate concentration and flavor scores. With the differences in fatty acid composition and the niche in the consumer beef market this product would target, it was important to examine the consumer reaction to Wagyu beef. The consumer triangle test indicated that the consumers could detect differences between steaks from Wagyu crossbred and Angus steers (Table 3). Of the 180 responses, there were 98 correct responses. This level of correct responses indicated that at a 99.5% TABLE 3 Consumer Triangle Test Comparison between Steaks from Wagyu Crossbred and Angus Steers
Test comparison 2 Wagyu vs 1 Angus 2 Angus vs 1 Wagyu Total number of correct responses
Correct responses 51 of 90 47 of 90 98 of 180
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S. G. May, C. A. Sturdivant, D. K. Lunt, R. K. Miller, S. B. Smith
50 .2.1
40 ~e
20 trl
10 0
SLIGHT
MODERATE MUCH MAGNITUDEOF THE DIFFERENCE
EXTREME
Magnitude of the differencebetween samples for the correct responses (n = 98).
Fig. 1.
confidence interval, 47-5% of the consumers could detect a difference in eating quality between steaks from Wagyu crossbred and Angus steers (random selection of samples would have resulted in one-third of the consumers detecting a difference). It is important to note that this test does not indicate which sample(s) the consumers actually preferred. The consumer panel indicated that the degree of difference was primarily 'slight' to 'moderate' with 76% of the correct responses in these two categories (Fig. 1). The major qualitative traits used to describe differv~ p.i 30 Z
20-
~
~
tO'
0'" Flavor Tenderness Juiciness
F&T
F&J
T&J
F,T&J
Fatty
QUALITATIVEDESCRIPTION Fig. 2.
Q u a l i t a t i v e d e s c r i p t o r s as a s s e s s e d b y the c o n s u m e r s w i t h correct r e s p o n s e s .
Fatty acid and sensory analysis of Wagyu and Angus beef
297
ences in eating quality were tenderness, juiciness and flavor. When the consumers were asked to indicate which trait(s) they used to determine the difference between samples, the majority of the correct respondents used a combination of tenderness and juiciness, while other consumers indicated the singular traits of tenderness and flavor (Fig. 1). Three percent of the panelists utilized a descriptor other than those commonly associated with eating quality (tenderness, juiciness and flavor). These panelists utilized 'fatty' as the descriptor. This may not be surprising with Wagyu crossbred steers having an average of 4.4% more ether extractable fat from the rib eye muscle than Angus steers (Lunt et al., 1993). In summary, differences in fatty acid composition existed between Wagyu crossbred and Angus steers fed identically, the most notable differences (P < 0.05) being a higher percentage of oleate and lower percentage of palmitate in SC and IM of Wagyu crossbred steers. Although both breeds produced high quality steaks, consumers could detect differences between breeds. ACKNOWLEDGEMENT Technical article 30921 from the Texas Agricultural Experiment Station. REFERENCES AMSA (1978). Guidelines for Cookery and Sensory Evaluation of Meat. American Meat Science Association, Chicago, IL. AOAC (1984). Official Methods of Analysis. Association of Official Analytical Chemists, Washington, DC. Dryden, F. D. & Marchello, J. A. (1970). J. Anim. Sci., 31, 36. Eichhorn, J. M., Coleman, L. J., Wakayama, E. J., Blomquist, G. J., Bailey, C. M. & Jenkins, T. G. (1986). J. Anita. Sci., 63, 781. Folch, J., Lees, M. & Stanley, G. H. S. (1957). J. Biol. Chem., 226, 497. Gillis, A. T. & Eskin, N. A. M. (1973). J. Food Sci., 38, 408. Huerta-Leidenz, N. O., Cross, H. R., Savell, J. W., Lunt, D .K., Baker, J. F., Pelton, L. S. & Smith, S. B. (1991). J. Anim. Sci., 69, 3665. Huerta-Leidenz, N. O., Cross, H. R., Savell, J. W., Lunt, D. K., Baker, J. F., Pelton, L. S. & Smith, S. B. (1993). J. Anim. Sci. 71,625. Leat, W. M. F. (1975). J. Agric. Sci., Camb., 85, 551. Link, B. A., Bray, R. W., Cassens, R. G. & Kauffman, R. G. (1970). J. Anim. Sci., 30, 722. Lunt, D. K., Riley, R. R. & Smith, S. B. (1993). Meat Sci., (accepted). Meilgaard, M., Civille, G. V. & Carr, B. T. (1987). Difference tests. In Sensory Evaluation Techniques, CRC Press, Boca Raton, FL. Melton, S. L., Amiri, M., Davis, G. W. & Backus, W. R. (1982). J. Anim. Sci., 55, 77.
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Mitsumoto, M., Yamashita, Y., Mitsuhashi, T. & Nakanishi, N. (1986). Jpn. J. Zootech Sci., 57, 257. Morrison, W. R. & Smith, L. M. (1964). J. Lipid Res., 5, 600. Peacock, F. M., Kroger, M., Palmer, A. Z., Carpenter, J. W. & Olson, T. A. (1982). J. Anita. Sci., 55, 797. SAS (1986). S A S User's Guide: Statistics. SAS Institute, Inc., Cary, CN. Steel, R. G. D. & Torrie, J. H. (1980). Principles and Procedures of Statistics: A Biometrical Approach, 2nd edn, McGraw-Hill, New York. Sturdivant, C. A., Lunt, D. K., Smith, G. C. & Smith, S. B. (1992). Meat Sci., 32, 449. Tanaka, S. (1985). Jap. J. Dairy & Food Sci., 34, 92. Westerling, D. B. & Hedrick, H. B. (1979). J. Anita. Sci., 48, 1343. Wheeler, T. L., Savell, J. W., Cross, H. R., Lunt, D. K. & Smith, S. B. (1990). J. Anita. Sci., 68, 3677. Yamazaki, T. (1981). Bull. Natl. Grassl. Res. Inst., 18, 69.