Perimysium thickness as an indicator of beef tenderness

Eight bovine muscles were evaluated to determine if perimysium thickness (PT) differed among carcasses of similar physiological age, and if those potential differences were related to the Warner-Bratzler shear (WBS) force values of cooked steaks from electrically stimulated and non-electrically stimulated carcasses that were subsequently aged up to 22 d postmortem. The effect of PT on the WBS of steaks divided into tenderness groups also was evaluated. Muscle and carcass affected (P < 0.05) PT. Electrical stimulation did not significantly affect PT, but did decrease Warner-Bratzler shear force (P < 0.05) of longissimus thoracis and longissimus lumborum steaks. Postmortem aging decreased the WBS force of steaks ( P < 0.05). Correlation coefficients revealed that perimsium thickness would be a poor indicator of WBS when used alone (r = 0.134). However, PT accounted for 20% of the variation in 14-d WBS force within tenderness groups. Regression analysis within tenderness groups showed that 67.71% and 63.07% of the variations in 3-d and 14-d WBS, respectively, could be accounted for in models that included PT. These results indicate that PT can be used, in conjuction with myofibrillar components of tenderness, to account for significant variation in WBS values of cooked beef steaks.