Changes in caspase activity during the postmortem conditioning period and its relationship to shear force in porcine longissimus muscle 1

The objective of this study was to inves- tigate the protease family caspases in skeletal muscle and their potential contribution to postmortem proteol- ysisandmeattenderization.TenLargeWhitegiltswere slaughtered, and samples of LM were taken at 0, 2, 4, 8, 16, 32, and 192 h after slaughter and immediately snap frozen in liquid nitrogen. Samples were subse- quently analyzed for caspase 3/7 and caspase 9 activity, protein levels of known caspase substrates, alpha II spectrin and poly (ADP-ribose) polymerase (PARP), as well as, at 192 h, shear force. Specific degradation prod- ucts of alpha II spectrin and PARP, which are known indicators of caspase activity, and apoptosis were de- tected on immunoblots of muscle samples taken over the postmortem period. The relationships between the changes observed in caspase activities and protein lev- els of PARP and spectrin across the entire postmortem