Effect of lipoxygenase-catalyzed linoleic acid oxidation on structural and rheological properties of silver carp (Hypophthalmichthys molitrix) myofibrillar protein.

The goal of this study was to investigate the effects of protein oxidation on myofibrillar protein (MP) gel structure and rheological properties using a lipoxygenase-linoleic acid system. The results showed that the addition of the linoleic acid significantly increased the protein carbonyl and dityrosine content (P < 0.05), whereas the contents of sulfhydryl and the free amino groups were increased first and then decreased. Circular dichroism spectra and surface hydrophobicity studies evidenced that the disruption of α-helix conformation and the exposure of hydrophobic sites were induced by oxidized linoleic acid (OLA). Results. Of SDS-PAGE indicated that non-disulfide covalent linkages were implicated in the formation of cross-linking in myofibrillar proteins induced by OLA. The rheological tests revealed that the storage modulus (G′) of OLA moderate oxidative modification (≤ 2.5mmol/L) significantly increased, whereas the storage modulus (G′) of OLA excessive oxidative modification (>2.5mmol/L) significantly decreased. Moreover, microstructure analysis indicated the presence...