Abstract: In this research, porcine myofibrillar protein (MP) was artificially oxidized in simulated oxidation systems (containing 10 μmol/L FeCl3, 100 μmol/L ascorbic acid, and 0, 0.5, 1, 3, 5 or 10 mmol/L H2O2) with a view to investigating the effects of different oxidation degrees on the structural characteristics and gel properties of myofibrillar protein. The results showed that the protein carbonyl content increased, while the contents of sulfhydryl groups and free amino groups and the endogenous fluorescence intensity decreased with the increase of H2O2 concentration. SDS-PAGE indicated that oxidative disulfide bond formation resulted in protein cross-linking and aggregation, and consequently a decrease of protein surface hydrophobicity and solubility. When the concentration of H2O2 was lower than 1.0 mmol/L, no significant change was observed in the heat-induced gel properties of MP. However, when the H2O2 concentration was higher than 1.0 mmol/L, the cooking loss increased significantly (P < 0.05) and the gel strength decreased obviously (P < 0.05), while the whiteness changed barely. Overall, H2O2 concentration was positively correlated with protein oxidation degree, but negatively correlated with gel strength.

Key words: oxidation, myofibrillar protein, protein structure change, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gel properties