Physiochemical and rheological properties of oxidized Japanese seerfish (Scomberomorus niphonius) myofibrillar protein.

Myofibrillar protein (MFP) of Japanese seerfish (JS) was oxidized by Fenton system (1, 4, 8, 16 mM H2 O2 for 0, 2, 4, 6 hr). After oxidation, α-helix ratio and sulfhydryl content of MFP declined along with the increased carbonyl and dityrosine levels. Bromophenol blue bound in MFP under 1 mM H2 O2 slightly increased. Polymers together with attenuated myosin heavy chain in protein pattern were observed. Compared with non-oxidized MFP, storage modulus (G') of MFP subjected to 1 mM H2 O2 for 4 hr increased while that of MFP exposed to 16 mM H2 O2 declined. When treated with microbial transglutaminase (MTG), mildly oxidized (1 mM H2 O2 , 2 hr) MFP showed higher G' while heavily oxidized (16 mM H2 O2 , 2 hr) MFP had lower G' than control. Oxidation showed pronounced influences on physiochemical and gelling properties of JS MFP and the oxidation extent affected MTG role on it. PRACTICAL APPLICATIONS: Protein oxidation occurs extensively in muscle and exerts great influences on muscle food quality. JS is widely used for producing gel food in China. Its muscle also contains oxidation initiators such as H2 O2, hemoglobin and lipids, increasing the susceptibility to protein oxidation. Results of the study exposed the effects of hydroxyl radical oxidation on physiochemical and gelling properties of JS MFP. It provides strategic support to improve gel properties of MFP by manipulating oxidation.