Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 2010
Publication Date: April 20, 2011
Citation: King, D.A., Shackelford, S.D., Wheeler, T.L. 2011. Relative contributions of animal and muscle effects to variation in beef lean color stability. Journal of Animal Science. 89:1434-1451. Interpretive Summary: Color deterioration during retail display of beef products is a problem that costs the U.S. beef industry an estimated $1 billion annually. Previous results from our laboratory have identified substantial animal-to-animal variation in the color stability of the ribeye muscle. However, substantial differences in color stability exist across muscles within a beef carcass; thus, the present experiment was conducted to compare color stability in 14 beef muscles and determine if color stability of muscles throughout the carcass is related to color stability of the ribeye muscle. The results of this experiment confirm previous reports of large differences in color stability across beef muscles. However, the color change during retail display of all the major muscles was moderately to highly associated with color change in the ribeye muscle. Thus, color stability of the major muscles in the carcass could be predicted by measuring the ribeye muscle and used to sort carcasses into color stability groups.
Technical Abstract: Beef carcasses (n = 100) were selected from a commercial processing facility. Longissimus lumborum (LM), semimembranosus (SM), biceps femoris (BF), gluteus medius (GM), triceps brachii (TB), rectus femoris (RF), vastus lateralis (VL), adductor (AD), semitendinosus (ST), infraspinatus (IS), teres major (TM), biceps femoris ischiatic head (BFIH), biceps femoris sirloin cap (BFSC), and gracillus (GR) muscles were removed, vacuum packaged, and aged until 14 d postmortem, when a steak was removed and placed in retail display for 9 d. Instrumental color variables (L*, a*, b*, hue angle, chroma, and delta E) were determined on d 0, 1, 3, 6 and 9 of display. Muscle pH and myoglobin content were determined for LM, SM, BF, GM, and TB. Muscles differed (P < 0.05) in initial values of each color variable evaluated. Furthermore, the extent and timing of changes in these variables during display differed across muscles. The magnitude of relationships between color variables measured in LM steaks to those measured in steaks from other muscles differed across days of display with the strongest relationships being observed earlier in the display period for labile muscles and later in stable muscles. Lightness of LM steaks was correlated to lightness of all of the other muscles evaluated regardless of day of display (r = 0.27 to 0.79). For a*, hue angle, chroma, and delta E values, the strongest relationships between LM values and those of other muscles were detected between d 9 LM values and those of other muscles on d 3, 6, or 9, depending on the relative stability of the muscle. Correlation coefficients between d 9 a*, hue angle, chroma, and delta E values in LM to those of other muscles were 0.50, 0.65, 0.28, 0.43 (P < 0.05) or greater, respectively, for the muscles included in the study. Myoglobin content of SM, BF, GM, and TB was highly correlated to that of LM (r = 0.83, 0.82, 0.72, and 0.67, respectively; P< 0.05). Muscle pH of LM was correlated to pH of SM and GM (r = 0.44 and 0.53; P < 0.05), but not pH of BF and TB. Muscle effects generally explained a greater proportion of variation in a*, b*, hue angle, chroma, and delta E than animal effects. However, the relative importance of animal effects increased as display continued. These data indicate that muscle effects were the largest contributor to beef color stability variation, but animal effects were consistent across muscles. Furthermore, remarkably strong relationships between LM color stability and the stability of other muscles indicate that strategies developed to manage animal variation in LM color stability would beneficially affect the entire carcass.