Effects of grape seed proanthocyanidin on the conformation and functional properties of mutton myofibrillar protein under hydroxyl radical-induced oxidative stress

The oxidative damage of meat proteins during processing and storage leads to the degradation of the quality of meat products. To overcome this problem, the effects of grape seed proanthocyanidin (GSP) on the antioxidant capacity, structure, and physicochemical properties of the mutton myofibrillar protein (MP) under oxidative stress conditions were investigated. The protein structure and aggregation behavior were characterized by indicators such as sulfhydryl groups, surface hydrophobicity, Fourier transform infrared spectroscopy (FT-IR) and zeta potential. The addition of GSP increased the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and hydroxyl radical scavenging activity (HRSA) and decreased the content of carbonyl and free amino groups. The sulfhydryl groups content, absolute value of zeta potential, and storage modulus (G′) of oxidized MPs were improved with the incorporation of GSP (10 mg/g protein). Intrinsic tryptophan fluorescence and FT-IR results indicated that GSP induced changes in protein conformation by reducing hydrophobic group exposure and restoring the α-helix. GSP, as a natural antioxidant, inhibited oxidative deterioration and modified the functional properties of meat products. This study provides a new way to improve the quality of meat products under oxidizing conditions.