Compositional Changes in Muscle of Malignant Hyperthermia–Susceptible Pigs Due to Postmortem Alterations in Lipid Metabolism, Lipid Peroxidation and Protein Oxidation

Pigs with mutated calcium release channels are stress-susceptible and are known for increased postmortem metabolism which results in inferior meat quality. The lipid composition, lipid peroxidation, and oxidation of proteins of skeletal muscle homogenates from the longissimus muscle of pigs were investigated. Muscle tissue samples were obtained from malignant hyperthermia-resistant (MHR) and hyperthermia-susceptible (MHS) pigs in a postmortem time course. Differences in the n-3 polyunsaturated fatty acid composition with higher values in the susceptible pigs were detected (MHR versus MHS: 141±5 versus 116±4 μg/g wet wt.; P<0.05). This was accompanied by a dramatic 40% postmortem vitamin E loss in MHS muscles (22 h MHR versus 22 h MHS: 1.66±0.11 versus 1.06±0.16 μg/g wet wt.; P<0.05). Muscle tissue from MHS pigs oxidized at a significantly higher rate in comparison with tissue from MHR animals. This difference was also observed for spontaneous malondialdehyde formation as well as for oxidant-induced peroxidation rate (0.75 h MHR versus 0.75 h MHS: 0.81±0.09 versus 1.33±0.09 nmol/g wet wt.; P<0.05). No difference was observed in protein oxidation level in MHS and MHR animals. It is concluded that the enhanced lipid oxidation rate could contribute to the dramatic changes in meat quality from MHS pigs.