Epigallocatechin-3-gallate mediated self-assemble behavior and gelling properties of the ovalbumin with heating treatment

Ovalbumin (OVA), is the most abundant protein in the egg white. In the present study, the effects of Epigallocatechin-3-gallate (EGCG) on the self-assembly behavior and gelling properties of OVA with different heating time were investigated. Electrophoresis, surface hydrophobicity, Fourier transform infrared (FTIR) spectroscopy and molecular docking analysis indicated that hydrophobic force and hydrogen bond were the predominant interactions between EGCG and OVA. The binding of EGCG to OVA suppressed the formation of fibrils as evidenced by the results of Thioflavin T (ThT) intensity and atomic force microscopy (AFM) analysis. When heated for 15–30 min, EGCG addition, especially at 2.5 μM/g, resulted in a decrease of ThT fluorescence intensity and hydrophobicity of OVA samples, and a formation of dense linear aggregates. However, the OVA solution did not form a gel. In a longer heating time of 45 min, 5 μM/g EGCG induced a significant decrease in ThT fluorescence intensity and hydrophobicity of OVA samples, and a transition from the dense linear aggregates to the dense spherical clusters. Therefore, the OVA samples realized the transition from the solution state to the gel state with a higher storage modulus (G′). When the heating time was extended to 60 min, all the OVA samples formed gel and reached the highest G′ at 5 μM/g EGCG. These results suggested that the suitable hydrophobic interactions and hydrogen bonds between EGCG and the OVA improved gel quality. Polyphenol binding provided a new way to regulate the assembly behavior and gelling properties of OVA.