Abstract: Coregonus peled from Sayram Lake in Xinjiang, China was used to study the changes in the biochemical properties of muscle proteins after protein oxidation using a FeCl3/H2O2/ascorbic acid (Asc) hydroxyl radical-generating system (HRGS). The results showed that oxidant concentration (1–20 mmol/L) and oxidation time (1–5 h) were positively correlated with the carbonyl content, dityrosine content and surface hydrophobicity of C. peled sarcoplasmic proteins (SP), but negatively correlated with the total sulfhydryl content, free amino content and Ca2+-ATPase activity. Statistically significant changes were observed for all the indexes (P < 0.05). After 5 h oxidation with the oxidant H2O2 (20 mmol/L), the contents of carbonyl groups and dityrosine and the surface hydrophobicity increased by 41.28%, 39.5% and 37.5%, respectively, while the total sulfhydryl content, Ca2+-ATPase activity and free amino group content decreased by 65.9%, 60.2% and 22.5%, respectively compared with the unoxidized group. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns demonstrated the formation of protein polymers and protein degradation caused by H2O2 oxidation at the molecular level. Our findings indicate that protein oxidation and biochemical alterations of C. peled SP have an influence on the quality of C. peled.

Key words: Coregonus peled, sarcoplasmic protein, protein oxidation, hydroxyl radical-generating system, biochemical properties