Effects of EGCG covalent modification on the antigenicity and functional properties of β-conglycinin

β-Conglycinin is the main component of soy protein. However, its potential allergenicity limits the application of soy protein in the food industry. The purpose of this study is to investigate the effects of covalent modification of epigallocatechin gallate (EGCG) on the immune and functional properties of β-conglycinin.

The antigenicity of β-conglycinin covalent complexes was significantly reduced compared to the untreated proteins. The antigenicity reduction of EGCG and β-conglycinin free radical complex was 37.97%, which was better than that of alkali complex (34.21%). The binding ability with seven epitope antibodies for EGCG and protein complex was significantly decreased. In vitro simulated digestion showed that with an increase of EGCG concentration, protein digestibility decreased, and the IgG binding ability of the complex decreased significantly after digestion, alkali complex reduced by 89.07% and free radical complex reduced by 88.63%. After modification, EGCG significantly increased the solubility, emulsification and emulsification stability of protein. After EGCG was covalently combined with β-conglycinin, the antioxidant capacity of the complex was significantly increased, and was proportional to the dosage of EGCG. DPPH, ABTS and FRAP assays revealed that the antioxidant capacity of the compounds prepared by alkali method was higher than that of the compounds prepared by free radical method. The covalent binding of EGCG to proteins improved their thermal stability (the temperature increased from 62.8 to 73.2 °C). Ultraviolet and infrared spectra showed that the covalent binding of EGCG to proteins caused changes in the structure of β-conglycinin.

Covalent modification with EGCG effectively reduced the antigenicity of β-conglycinin and improved its functional properties and antioxidant capacity. This study provides a theoretical basis for the development of soy protein products with low allergenicity and high functionality. © 2026 Society of Chemical Industry.