| The first of three studies was conducted to determine if tenderness of callipyge (CLPG) lamb longissimus muscle (LM) could be improved by: (1) extending aging time to 48 d postmortem (PM) or (2) preventing pre-rigor shortening by clamping the right LM between two metal plates. Clamped LM had lower WBS values possibly by reducing rigor shortening of the sarcomeres and extended aging resulted in acceptable WBS values in CLPG LM, concurrent with appearance of troponin-T (TNT) degradation products. Study two was conducted to evaluate attributes associated with LM tenderness in divergent breeds, Wagyu (W, n = 12), Limousin (L, n = 12) and F1-cross (WxL, n = 12) cattle, fed two dietary treatments (0 or 6% sunflower oil). At d 1 PM, W tended ( P > 0.05) to have higher WBS values than WxL or L, however by d 14, W required 0.77 kg less (P < 0.05) force to shear and had higher (P < 0.05) sensory panel sustained tenderness scores than L. Initial appearance of the TNT 30 kDa fragment was greater in L, yet the rate of TNT degradation between d 1 and d 14 PM was more rapid for W than for L. The objective and methods for study three were the same as for study two except the semitendinosus muscle (ST) was evaluated. Wagyu x Limousin steaks aged 1 d PM tended to have lower (P > 0.1) WBS values, and those aged 14 d PM had lower (P < 0.05) WBS values than L. These breed differences were not explained by collagen content or collagen crosslinking.; Tenderness differences in both lamb and beef LM may be facilitated by a more rapid proteolytic degradation rate, which was concurrent with acceptable levels of WBS. In beef, ST WBS differences existed, but were not explained by measurements performed in this study. Other means of guaranteeing tender ST steaks should be investigated aside from genetic selection. |
