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This study evaluated the effects of d -galactose (DG) concentration on the functional characteristics, physicochemical properties, structure and non-covalent binding ability of pH shifting treated soybean glycinin (S–11S). Multispectral and microscopic imaging analysis showed that the pH shifting induced soybean glycinin self-assembly into more stable small particle size aggregates, and the functional properties of S–11S were significantly enhanced. The introduction of DG further enhances the functional properties of S–11S, and the solubility and emulsification activity of the composite system are inversely proportional to the concentration of DG. In order to clarify the reason for the change, multispectral analysis found that the tertiary structure of S–11S was de-folded and the disordered structure was increased, which induced S–11S and DG to form smaller and stable nanoparticles than S–11S through hydrophobic forces and hydrogen bonding, and the optimal binding ratio was 10.8:1. In addition, the simulation results of molecular dynamics and molecular docking are in agreement with the experimental results. Therefore, the addition of DG can stabilize the overly discrete S–11S conformation and improve its functional characteristics. These results provide a theoretical basis for the application of modified protein and monosaccharide composite products in food and materials. [Display omitted] • PH-shifting changed the multilevel structure and functional properties of 11S. • Stoichiometry of the modified 11S and d -galactose in the complex was 10.8. • Weak-affinity complex was formed mainly via hydrophobic interaction and H bonding. • The stability and functional properties of complex were better than modified 11S. [ABSTRACT FROM AUTHOR]

• The modified glycinin (S-11S) is complexed with d -galactose (DG). • Heat promotes the covalent interaction of S-11S and DG at Cys and Phe sites. • The structure of the S-11S/DG colloidal particles is altered by heating. • Temperature affects the aggregation behavior of the S-11S/DG colloidal particles. • The S-11S/DG colloidal particles formed network gel easily. The molecular structure and morphologies of complex colloidal particles with modified glycine (S-11S) and d -galactose were studied by multispectral, microscopic imaging and chromatographic techniques at different temperatures, and the self-assembly and aggregation mechanisms were determined. Overall, high-temperature-treated S-11S and d -galactose associate at cysteine and phenylalanine sites and self-assemble into colloidal particles of greater stability than glycinin and S-11S via ionic and disulfide bonds. The structure and subunit content of composite colloidal particles were changed. Assessing the sub-microstructure reveals that temperature can regulate the directional aggregation of complex colloidal particles. The elasticity of the complex colloidal particles is maximum enhanced at 95 ℃ as confirmed by the rheological. Thus, the heat-treated aggregation of the soy protein and its complex was evaluated to provide a new theoretical basis for the application of soy protein in gels and other areas and contribute to the design of new soy protein products. [ABSTRACT FROM AUTHOR]