Effects of the Extract of Gnaphalium affine on the Oxidation and Structure of Myofibrillar Protein Induced by ·OH

The effects of tea polyphenols (TP) and Gnaphalium affine extract (GAE) at different concentrations (0, 1.2, 6, 30 mg/g protein) on the oxidation and structural changes of porcine myofibrillar proteins (MPs) were studied using Fenton oxidation system to simulate the actual meat oxidation environment. The results showed that GAE had a strong ability to scavenging free radicals, which could significantly inhibit the formation of carbonyl group and promote the loss of sulfhydryl group (P<0.05), as did TP. Especially under high concentration, TP and GAE inhibited 36.89% and 38.93% carbonyl formation, and promoted 28.89% and 27.40% sulfhydryl loss, respectively. In addition, TP and GAE both had strong quenching effect on the endogenous fluorescence of MPs, promoted the further expansion of the protein structure, aggravated the loss of α-helical conformation caused by oxidation, exposed more active groups, and significantly increased the hydrophobicity on the protein surface and protein insolubility (P<0.05). The higher the concentration of TP and GAE, the greater the effect on the oxidation and structural changes of MPs, but GAE was not as effective as TP in regulating the oxidation of MPs and its interaction with proteins.