Abstract: Myofibrillar protein (MP) plays a determinant role in the gel properties and sensory quality of meat products, but it is vulnerable to oxidative attack during processing and storage. In this study, the effect of different concentrations of L-Arg (1, 3, 5 and 10 mmol/L) on the structure and gelling properties of MP was investigated under oxidative conditions induced by a hydroxyl radical-generating?system. After the treatment, the conformational changes of MP were analyzed by sulfhydryl group (–SH) measurement and tintrinsic tryptophan fluorescence spectroscopy, and the cross-linking and aggregation of MP was analyzed in terms of particle size and solubility as well as by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The gelling properties of MP were evaluated using a rheometer, a texture analyzer and a scanning electron microscope (TEM). The secondary structure of protein gels was analyzed by Raman spectroscopy. The experimental results showed L-Arg affected the structural and gelling properties of MP under oxidation conditions in an obvious concentration-dependent manner. L-Arg at concentrations of 1–5 mmol/L had a certain protective effect on the content of –SH groups, while 10 mmol/L L-Arg resulted in significantly decreasing the content of –SH groups. The addition of L-Arg reduced the fluorescence intensity of endogenous tryptophan and increased particle size. SDS-PAGE showed that the oxidation-induced formation of disulfide bonds resulted in protein cross-linking and aggregation, thereby leading to a decrease of solubility. With the increase in L-Arg concentration, the microstructure of MP gels became more compact, accompanied by a gradual decrease of gel strength and whiteness and a gradual increase in gel yield. On the whole, under the oxidative condition, addition of 5 mmol/L L-Arg significantly increased the content of sulfhydryl groups, and decreased cooking loss and gel strength, thus improving the oxidation stability of meat protein and consequently the tenderness and water-holding capacity of meat products.

Key words: L-Arg; myofibrillar protein; oxidation; structural change; rheological properties; gelling properties