Abstract: In order to study the effect of quercetin on the structure and gel properties of pork myofibrillar protein under oxidative conditions, an oxidation system (40 mg/mL protein, 10 μmol/L FeCl3, 100 μmol/L VC, and 1 mmol/L H2O2) was established and quercetin at different concentrations (10, 50, 100, 150 μmol/g) was added to the system. Sulfhydryl content, surface hydrophobicity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern, gel strength, water-holding capacity, microstructure, rheological properties and hydration characteristics were determined after 12 h of incubation in the system. The results showed that quercetin significantly reduced the total sulfhydryl content of myofibrillar protein (P < 0.05). Quercetin at 10 μmol/g decreased the surface hydrophobicity and increased it slightly at higher concentrations. Quercetin weakened the intensity of the band of the myosin heavy chain (MHC) and it also weakened the intensity of the band of actin at concentrations of 100 and 150 μmol/g. Both the MHC and actin participated in the formation of macromolecular protein aggregates and the aggregates could be reduced. Quercetin enhanced the gel strength and water-holding capacity and made the gel microstructure more compact. It resulted in partial conversion of free water into immobile water and enhanced the water-binding capacity as well as the G’ and G” of the protein. Therefore, quercetin improved the gel properties of myofibrillar protein by covalently cross-linking with its sulfhydryl group and properly enhancing its surface hydrophobicity; moreover, quercetin could concentration-dependently enhance the gel-forming capacity of myofibrillar protein.

Key words: quercetin; myofibrillar protein; structure; gel properties