Effects of different binding strategies of D-galactose and glycinin on the thermal gelation behavior of the composite system.

In this study, non-covalent and covalent interactions between D-galactose (DG) and glycinin (11S) were induced using a pH-shift method. This approach represents an innovative advancement in existing protein-monosaccharide binding strategies. Furthermore, the study investigated the resulting changes in gel behavior and the properties of the composite thermal gels. The solubility and Zeta-potential analysis showed that the non-covalent interaction (S-11S/DG) was more stable and less dispersed than the covalent interaction (S/DG-11S). Rheological results showed that S-11S/DG has higher viscosity and can form stable elastic gel after temperature program. FTIR and intermolecular force results indicated that both gels utilized disulfide bonds as the primary covalent force, with additional chemical bonds playing a secondary role in maintaining the stability of the gel network and surrounding water molecules. However, the S/DG-11S exhibits a looser structure, resulting in a less elastic and thinner network structure. In contrast, the S-11S/DG gel network demonstrated increased elasticity and support, enhancing its hardness, cohesion and water holding capacity. Thus, the pH-shifting-induced non-covalent gel system had more stable network structure and better properties than the pH-shifting-induced covalent gel system. This study offered new insights for constructing soybean protein gel systems and advancing the design of novel soybean protein products.