The purpose of this study was to examine the role of mitochondria in postmortem calcium homeostasis and its effect on proteolysis and tenderness. We hypothesized that mitochondria buffer cytosolic calcium levels and delay the activation of calpain-1 and subsequently the development of meat tenderness. To test this hypothesis, pre-rigor bovine longissimus thoracis et lumborum muscle samples were injected with DS16570511 to inhibit mitochondrial calcium uptake. Free calcium, tenderness, texture profile analysis (TPA), calpain-1 activity, and proteolysis were evaluated over a 336 h aging period. Inhibition of mitochondrial calcium uptake increased (P < .0001) cytosolic calcium concentration and calpain-1 autolysis and activity at 24 h compared to control steaks. Further, tenderness and TPA at 168 and 336 h, calpastatin degradation at 24 h, and proteolysis at 168 h were all enhanced (P < .05) in the treated steaks. Collectively, these data indicate that inhibition of mitochondrial calcium uptake can enhance postmortem proteolysis and tenderization through an early activation of calpain-1.
Keywords: Calcium homeostasis; Calpain-1; Mitochondria; Proteolysis; Tenderness.
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