Effects of quercetin on the gel properties of pork myofibrillar proteins and related changes in protein conformation

To study the effects of quercetin on the functionality of myofibrillar proteins (MPs), various levels of quercetin (0, 10, 50, 100 and 200 μmol g-1 protein) were added to MP solution and the structure and gel properties of MPs were determined.Compared with the control MPs not treated with quercetin, adding 10, 50 and 100 μmol g-1 quercetin caused a significant (P < 0.05) loss of sulfhydryls; 10 and 50 μmol g-1 quercetin enhanced the surface hydrophobicity significantly (P < 0.05), and 50, 100 and 200 μmol g-1 quercetin reduced the fluorescence intensity of tryptophan. Additions of 50, 100 and 200 μmol g-1 quercetin resulted in a significant (P < 0.05) reduction in MP solubility. Adding 10, 50 and 100 μmol g-1 quercetin did not significantly (P > 0.05) change the gel strength and water-holding ability of MPs than control, but 200 μmol g-1 quercetin declined the gel properties significantly (P < 0.05). The microstructure and dynamic rheological properties confirmed the results of the gel properties of MPs affected by various levels of quercetin.The results obtained in the present study show that mildly high levels of quercetin can maintain the gel properties of MPs, which may be a result of the moderate MP cross-linkage and aggregation caused by the covalent and non-covalent interactions of MPs. © 2023 Society of Chemical Industry.