Abstract: In order to investigate the effect of oxidation on the physicochemical and molecular properties of mutton myofibrillar protein, the carbonyl content, total sulfhydryl content, dimeric tyrosine content, surface hydrophobicity, ultraviolet absorption spectrum, endogenous fluorescence spectrum, Fourier transform infrared (FTIR) spectrum, particle size, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profile of myofibrillar protein samples with different oxidation durations were analyzed. The results showed that the carbonyl content, dimeric tyrosine content and surface hydrophobicity increased, while the total sulfhydryl content and fluorescence intensity decreased with the extension of oxidation time. Oxidation increased the particle size of myofibrillar protein and decreased the absolute value of Zeta potential. FTIR analysis showed some changes in the protein secondary structure when the oxidation time increased. The proportion of α-helix increased first and then decreased, the proportion of random coil did not obviously change, the proportion of β-sheet showed a decreasing trend, and the proportion of β-turn decreased first and then increased. SDS-PAGE indicated that oxidation caused cross-linking between protein molecules. The cystine content showed an increasing trend with prolonged oxidation time, while the reverse trend was seen for other amino acids.

Key words: protein oxidation; myofibrillar protein; molecular characteristics; physicochemical properties