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

¹ Department of Animal Science, University of Wyoming, Laramie, WY 82071

^* To whom correspondence should be addressed. E-mail: mindu{at}uwyo.edu.

	Abstract

Postmortem proteolysis is an important determinant in 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 (LM) and sternomandibularis muscle samples were obtained at 0 h, 0.25 h, 1 h, 3 h, 24 h, 72 h, and 240 h postmortem from 5 different steers. In experiment 2, a group of 40 beef cattle were 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 LM. And 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 h (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 LM immediately postmortem was higher (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.

Key Words: beef, caspase 3, postmortem, proteolysis, tenderness