Assessment of structural, textural, and gelation properties of myofibrillar protein of silver carp (Hypophthalmichthys molitrix) modified by stunning and oxidative stress

This study aimed to investigate the effect of stunning and oxidative stress on gelation properties and water distribution of myofibrillar protein (MP) of silver carp fillets. Different stunning methods (percussion, ice/water, and gill cut) were conducted prior to in vitro MP oxidation by hydroxyl radicals generated from Fenton reaction (10 μM FeCl₃, 0.1 mM ascorbic acid, and 0, 0.1, 0.5, 1, 5, and 10 mM H₂O₂) to simulate oxidative environments during surimi processing. The results indicated that gill cut-stunned fillets had greater susceptibility to MP unfolding and oxidation in terms of elevated disulfide bonds, carbonyls, and surface hydrophobicity. Regardless of stunning stress, mild oxidative modifications (0.1–1 mM H₂O₂) facilitated the enhancement of gel-forming ability, while strong oxidative environments (5–10 mM H₂O₂) exhibited weakened gel strength with reduced textural properties. In addition, gill cut-stunned fillets showed higher free water content (16.73%) and attenuated gel strength (278.12 g mm), reflecting fragile gel network and poor water-holding capacity in oxidized MP gels. In conclusion, gill cut stunning were not recommended in aquatic processing in terms of inferior water retention and decreased deformation and springiness of gels.