Alteration of Mitochondrial Lipidome and Its Potential Effect on Apoptosis, Mitochondrial Reactive Oxygen Species Production, and Muscle Oxidation in Beef during Early Postmortem

Lipid molecules are important participants in mitochondria-mediated apoptosis. This study explored the effect of mitochondrial lipids on mitochondria-mediated apoptosis, mitochondrial reactive oxygen species (ROS) production, and muscle oxidation of beef longissimus lumborum (LL, n = 6) and psoas major (PM, n = 6) during 24 h postmortem. A total of 432 lipid species matched with 21 lipid classes were identified. Remarkably, at 12 h postmortem, the levels of cardiolipin and phosphatidylserine in PM and ceramide, cardiolipin, phosphatidylserine, and sphingosine in LL increased significantly compared with 1 h postmortem, indicating that mitochondria-mediated apoptosis in beef muscle was accelerated during early postmortem. Moreover, PM had higher levels of cardiolipin and phosphatidylserine than LL, also suggesting a higher degree of apoptosis in PM during postmortem. Lipid molecules may assist the production of mitochondrial ROS and decrease the mitochondrial membrane potential (MMP) during postmortem apoptosis, resulting in muscle oxidation and the damage of antioxidant system. Notably, compared with LL, PM had higher abundance of apoptosis-related lipid molecules, a higher amount of ROS, faster diminishment in MMP, and then a higher degree of apoptosis. These findings provided new insights into the apoptosis and muscle biochemistry in beef during early postmortem.