Caspase 3 is not likely involved in the postmortem tenderization of beef muscle

Postmortem proteolysis is an important determinant of beef tenderness. Caspase 3 is a protease that functions in apoptosis and has been shown to degrade myofibrillar proteins. Our objective was to evaluate whether caspase 3 activity is related to beef tenderness and muscle growth, and whether caspase 3 is activated in postmortem beef muscle. In experiment 1, longissimus thoracis (LT) and sternomandibularis muscle samples were obtained at 0, 0.25, 1, 3, 24, 72, and 240 h postmortem from 5 steers. In experiment 2, a group of 40 beef cattle was slaughtered at the University of Wyoming Meat Lab with 10 steers of different tenderness and growth characteristics chosen for the analysis of caspase 3 activity in the LT. In experiment 3, 10 steers with different tenderness but matched growth characteristics were chosen for analyses. In experiment 1, no significant activation (P = 0.70) of caspase 3 activity was detected; only a decreased activity at 72 (P = 0.05) and 240 h (P = 0.02) postmortem was observed. Western blot analysis of both muscle samples showed only the pro-caspase 3 form and failed to detect the activated enzyme. In experiment 2, caspase 3 activity in the LT immediately postmortem was greater (P = 0.05) for the cattle with increased Warner-Bratzler shear force values. No difference in caspase 3 activity was detected for experiment 3. Our results demonstrate that caspase 3 activity is not activated, with its activity decreasing with time postmortem, and caspase 3 activity is not associated with Warner-Bratzler shear force at slaughter. Therefore, caspase 3 is not anticipated to be involved in postmortem tenderization of beef.