Abstract: In this study, we investigated the effect of metmyoglobin (MetMb) oxidation on the biochemical characteristics of yak muscle myofibrillar proteins at 24 h postmortem. The pattern of change in the contents of carbonyl, sulfhydryl and disulfide bonds, surface hydrophobicity, Ca/K-ATPase activity and dimeric tyrosine in myofibrillar proteins was determined after 24 h of oxidative incubation of MetMb at different concentrations (0, 0.01, 0.05 and 0.5 mmol/L). A sample without any added oxidant was served as a control. The results showed that with the increase in MetMb concentration, the oxidation level of myofibrillar proteins varied. The contents of carbonyl, disulfide bond and dimeric tyrosine, surface hydrophobicity, and Ca-ATPase activity significantly increased (P < 0.05), whilst the opposite was true for sulfhydryl content and K-ATPase activity (P < 0.05). When MetMb concentration increased to 0.5 mmol/L, the carbonyl content increased by 5 flod, while the sulfhydryl content decreased by 31.5% as compared with the blank treatment group. In summary, the oxidation of MetMb promotes the oxidation of myofibrillar proteins. The results of this study provide a reference for protein oxidation control during the production and processing of yak meat.

Key words: oxidation of methemoglobin, yak meat, myofibrillar protein, protein