Abstract: The purpose of this study was to solve the problem of low extraction rate of rice bran protein and poor product functions and properties in order to increase the utilization rate of rice bran protein. The effects of pH on the structure, solubility and surface hydrophobicity of rice bran albumin and globulin were investigated based on the theory of protein chemistry and spectroscopic analysis. The results showed that with the increase in pH, the hydrodynamic diameter distribution of rice bran albumin and globulin followed a declining trend while the zeta potential absolute value exhibited an increasing trend. The content of α-helix and random coil structure in rice bran albumin increased gradually, while the content of β-fold structure decreased gradually. Tryptophan residues of rice bran albumin and globulin tended to be “exposed”. In conclusion, under alkaline conditions, rice bran globulin remained most of its secondary structures and subunit dissociation induced the tertiary structure of the protein, which was the main reason for the increase in the surface hydrophobicity. As for rice bran albumin, the transformation of secondary structural units from an ordered to a disordered state and subunit dissociation-induced protein unfolding were the reason for the increase in the surface hydrophobicity. The increase in the solubility of rice bran albumin and globulin was accounted for by the fact that the subunits were dissociate into small particles and the protein particles were charged under alkaline conditions.

Key words: pH; rice bran protein; structure; solubility; surface hydrophobicity