Effect of Hydroxyl Radical Oxidation on the Structure and Emulsifying Properties of Beef Myofibrillar Protein

After different degrees of oxidation in the Fenton system, the changes in the structure and emulsification properties of beef myofibrillar proteins were investigated and the relationship between them were evaluated. The results showed that with increasing H₂O₂ concentrations from 0 to 20 mmol/L, the oxidation of myofibrillar protein became more serious, the carbonyl content, dimer tyrosine content and surface hydrophobicity increased gradually, and the contents of total sulfhydryl and free sulfhydryl groups decreased gradually; the percentage of α-helix exhibited a downward trend and the percentage of β-sheet showed an upward trend; solubility, emulsification activity and emulsion stability all tended to first increase and then decrease, while the opposite trend was observed for turbidity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that oxidation induced protein cross-linking. Correlation analysis found that the contents of carbonyl, sulfhydryl and dimer tyrosine, surface hydrophobicity and secondary structure indicators had significant correlations with solubility, turbidity and emulsification properties. In summary, the oxidation degree of myofibrillar protein increased gradually with increasing H₂O₂ concentration in the Fenton oxidation system, causing changes in its structure and emulsification properties.