Early postmortem skeletal alterations effect on sarcomere length, myofibrillar fragmentation, and muscle tenderness of beef from light-weight, Brangus heifers

Approximately 2 h after exsanguination, two skeletal cuts (TC) were made on randomly selected sides from 13 light-weight, Brangus heifers; companion s ides served as untreated controls (C). After a 24-h chill period, four musc les (Longissimus muscle from the IMPS#1 12A ribeye roll, LT, and from the I MPS#180 strip loin, LL; Biceps femoris, BF; Semitendinosus, ST, and Semimem branosus, SM) were excised from each side, vacuum-packaged, and aged for 7 days. Five 2.54-cm thick steaks were cut from each of the muscles to determ ine the effectiveness of the TC treatment on sarcomere length (SL), myofibr illar fragmentation index (MFI) and cooked beef tenderness. The LT and LL s teaks from TC-carcasses had longer (P < 0.05) sarcomeres, and the TC treatm ent decreased (P < 0.05) Warner-Bratzler shear (WBS) force values for the L T and LL by 35.8 and 33.2% respectively. Moreover, SL of the muscles from t he round were also increased (P < 0.05) by the TC procedure, but WBS force values were not different (P > 0.05) from C. Muscles from the TC sides had similar (P > 0.05) MFI values to those from control sides. This study demon strated that the TC procedure, when applied 2 h postmortem, can effectively improve cooked beef tenderness of the Longissimus muscle.