Abstract
Muscle profiling improves value and optimization of beef carcasses by expanding knowledge of physical, com-positional, and marketable attributes of single-muscle cuts. Extensive profiling for individual muscle portions of the NAMI #184 beef top sirloin butt remains understudied. The objective was to compare fluid loss, objective color (L*, a*, b*), pH,and objective tenderness of the biceps femoris (BF), gluteus accessorius (GA), gluteus medius, dorsal (GMD), and gluteus medius, ventral (GMV). Beef top sirloin butts (N=70) were collected from carcasses ranging in quality grade (USDA Select and Top Choice), hot carcass weight (light≤362 kg, medium=363 to 453 kg, heavy≥454 kg), and ribeye area (REA; small≤27.8 cm2, medium=27.9 to 40.6 cm2, large≥40.7 cm2). Warner-Bratzler shear force values were the low-est for the BF and GA (P<0.001) and were significantly different than the GMD and GMV. The GA reported the lowest percentage of fluid loss in raw and cooked forms (P<0.001, P<0.001) and the highest pH (P<0.001). The GMD exhibited the highest percentage of raw purge (P<0.001), highest L* value (P<0.001), and highest shear force (P<0.001). The GMV had the highest percentage of cook loss (P<0.001). USDA Top Choice muscles were more tender than Select (P<0.001) with higher L* value (P<0.001). All 4 top sirloin muscles and muscle subunits had average peak shear force values below 3.9 kg, and thus, all were within the threshold for USDA “very tender.” These muscle profiling data will aid in identifying new beef value cuts from the top sirloin butt and assess acceptability of sirloin cuts for further retail and foodservice merchandising opportunities.