Influence of Ca2+ on mitochondrial apoptosis activation and yak meat tenderization during postmortem aging

The objective of this study was to investigate the underlying molecular mechanisms of mitochondrial Ca2+ homeostasis disequilibrium in mitochondrial apoptosis and its impact on yak meat tenderness. Results indicated that CaCl2 treatment significantly promoted glycolysis by increasing lactic acid level and decreasing glycogen content, pH, and ATP production (P < 0.01 and P < 0.05). The activities of Na+-K+-ATPase pump and Ca2+ ATPase pump in the early aging stage were significantly influenced by CaCl2 treatment. The activities of synchronous digital hierarchy and citrate synthase were also significantly improved by CaCl2 treatment (P < 0.01 and P < 0.05). Mitochondrial reactive oxygen species (ROS) levels were significantly higher in the CaCl2 group than in the control group (P < 0.01); at 24 h, the value in the Ca2+ group was 64.27% higher than that in the control group. Furthermore, CaCl2 treatment significantly enhanced the mitochondrial apoptosis cascade reaction and meat tenderization by improving the myofibril fragmentation index and shear force (P < 0.01). These results demonstrated that the imbalance of mitochondrial Ca2+ homeostasis played a significant role in the mitochondrial apoptosis pathway by regulating energy metabolism factors, meat intracellular environment, mitochondrial functions, and ROS-mediated oxidative stress. These conditions further improved meat tenderization during postmortem aging.