Effects of gamma ray irradiation-induced protein hydrolysis and oxidation on tenderness change of fresh pork during storage.

This study investigated the effect of irradiation (0, 3, 5 or 7 kGy) on the tenderness changes of pork during storage at 4 °C for two weeks by determining the total carbonyl, sulfhydryl groups, peptidomic profiles, Warner-Bratzler (WB) shear force value and by gel electrophoresis (SDS-PAGE) experiment. The results showed that, irradiation significantly increased total carbonyl content of pork but had no significant effect on sulfhydryl groups. Protein thiol loss induced by irradiation was greatly promoted after storage for 3 days. Increasing irradiation dose level could significantly decrease the WB shear force value of samples (P < .05) by provoking degradation of myofibrillar protein and collagen fragments. During refrigerated conditioning, however, the WB shear force values increased significantly despite irradiation (P < .05). This was attributed to increasing amount of collagen solubilized from muscle, protein aggregation induced by carbonylation of troponin T (at 7 days of storage) and further cross-linking of myosin heavy chain (MHC) (at 14 days of storage).