Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/16/2003
Publication Date: 2/20/2004
Citation: Rhee, M., Wheeler, T.L., Shackelford, S.D., Koohmaraie, M. 2004. Variation in palatability and biochemical traits within and among eleven beef muscles. Journal of Animal Science. 82:534-550. Interpretive Summary: Many cuts of beef have been identified as needing improvement in tenderness relative to consumer expectations. These lower quality cuts make up a majority of the carcass and have been declining in value relative to higher quality loin cuts. Extensive knowledge of meat tenderness variation and meat palatability has been developed for the ribeye muscle. However, much less is known about variation in biochemical traits among other major beef muscles. The objectives of this study were to determine 1) the extent of variation in biochemical and palatability traits within and among eleven major beef muscles, and 2) within and among muscle relationships between biochemical and palatability traits. Results indicate some muscles vary greatly in protein degradation during refrigerated storage, muscle shortening during rigor mortis development, and/or connective tissue potentially contributing to their tenderness variation. Some cuts (top round, bottom round, and mock tender) contain muscles that are reduced in tenderness due to muscle shortening. Some cuts (mock tender, sirloin tip, top round, shoulder clod, and eye of round) contain muscles that are reduced in tenderness due to limited protein degradation. Some cuts (mock tender, eye of round, bottom round, top round, shoulder clod, and sirloin tip) contain muscles that are reduced in tenderness due to excess connective tissue. Some muscles may be reduced in tenderness due to a combination of these biochemical factors. These data indicate that tenderness and tenderness-related traits are highly variable within and among many major beef muscles and provide a basis for the development of muscle-specific strategies for improving the quality and value of beef cuts. Providing consumers with more consistently tender beef products will increase consumer satisfaction and should improve the value of the enhanced beef cuts, and, thus, carcasses, back through the production chain.
Technical Abstract: The objectives of this study were to determine 1) the extent of variation in biochemical and palatability traits within and among eleven major beef muscles, and 2) within and among muscle relationships between biochemical and palatability traits. Longissimus thoracis et lumborum (LD), psoas major (PM), gluteus medius (GM), semimembranosus (SM), adductor (AD), biceps femoris (BF), semitendinosus (ST), rectus femoris (RF), triceps brachii (TB), infraspinatus (IS), and supraspinatus (SS) from one carcass side of thirty-one Charolais x MARC III steers were vacuum-packaged, stored at 2 deg C until 14 d postmortem, then frozen at -30 deg C. The steaks (2.54 cm thick) were obtained from two or three locations within muscles for biochemical traits and Warner-Bratzler shear force, and from near the center for sensory traits. The PM was most tender, followed by IS, in both shear force and tenderness rating (P < 0.05). The other muscles were not ranked the same by shear force and tenderness rating. The BF had the lowest (P < 0.05) tenderness rating. The PM, GM, and LD had lower collagen concentration (2.7 to 4.5 mg/g muscle) than muscles from the chuck and round (5.9 to 9.0 mg/g) except for AD (4.9 mg/g). Desmin proteolysis was highest for BF and LD (60.2 and 59.9% degraded), and was lowest for PM (8.2%). The PM, TB, IS, RF, and ST had relatively long sarcomere length (> 2.1 um). The GM had the shortest (P < 0.05) sarcomere length (1.7 um). Cooking loss was lowest for BF (18.7%), followed by LD and IS (20.7%), and was highest for ST (27.4%). Across all muscles, tenderness rating was highly correlated (r > 0.60) to shear force, connective tissue rating, sarcomere length, and collagen content. Within a muscle, correlations among all traits were generally highest in LD and lowest in AD. Within muscle location effects were detected (P < 0.05) on shear force (PM, ST, BF, SM, and RF), sarcomere length (PM, ST, BF, LD, SS, IS, SM, and RF), collagen concentration (PM, BF, SS, IS, SM. AD, TB, and RF), desmin degradation (PM, GM, BF, SM, AD, and, RF), and cooking loss (all muscles except SS and AD). There is a large amount of variation within and among muscles for tenderness traits and tenderness related biochemical traits. These data increase our understanding of the sources of variation in tenderness in different muscles and provide a basis for the development of muscle specific strategies for improving the quality and value of muscles.