Abstract: Protein oxidation will induce changes in functional properties of food proteins and further influence the quality of food. In order to determine the influence of oxidation on functional and heat-induced gel properties of Pampus argenteus muscle protein, we examined the changes in the solubility and emulsifying properties of fish myofibrillar protein (MP) and the water-holding capacity, color and microstructure of heat-induced gels of MP. The results showed that the solubility, emulsifying activity and emulsion stability of MP from P. argenteus were related to the concentration of H2O2 in the model oxidation system. At low concentration of H2O2, all three indicators reached the highest value at 1 h of oxidation, while there was a declining trend with oxidation time at high concentration of H2O2. Water-holding capacity, hardness and springiness of MP gels increased firstly and decreased afterwards, the color parameter L* value rose, and b* value decreased during the oxidation process. At 3 h of oxidation, the microscopic structure of MP gels became more dense and cross-linked at low concentration of H2O2. On the other hand, at high concentration of H2O2, MP particles were gathered into a compact network structure during initial stages of oxidation, which was then completely destroyed at 5 h. Therefore, moderate hydroxyl free radical-induced oxidation of MP from P. argenteus muscle can improve its functional and heat-induced gel properties, but excessive oxidation will cause protein denaturation and aggregation and lower the quality of fish muscle.

Key words: Pampus argenteus, protein oxidation, functional properties, gel quality, microstructure