Postmortem pH, myofibrillar fragmentation, and calpain activity in Pectoralis from electrically stimulated and muscle tensioned broiler carcasses.

Broiler carcasses were conventionally processed or were electrically stimulated (ES) and had their Pectoralis muscles tensioned during rigor mortis development (ES/MT) to evaluate the relationship between the course of postmortem muscle pH decline and myofibrillar fragmentation. Samples from Pectoralis fillets harvested at 0, 0.5, 1, 2, and 24 h postmortem were analyzed for pH, myofibrillar fragmentation index, and calpain activity. The ES/MT treatment resulted in a more rapid pH decline and less myofibrillar fragmentation at all postmortem times sampled than conventional processing. Two distinct periods of fragmentation were noted for samples from both conventionally processed and ES/MT carcasses. These results agreed with the previous studies that this ES/MT treatment accelerated the normal postmortem pH decline, inhibited calpain activity, and thereby prevented postmortem proteolysis occurring during meat aging.