The impact of pH shifting combined high-pressure homogenization on structural and functional properties of rice dreg protein

The composition and aggregation of rice dreg protein (RDP) have a major impact on its properties. The aim of the present study was to investigate the effects of pH shifting combined high-pressure homogenization (HPH) treatment on functional properties of RDP. The improvement of RDP functional properties with pH shifting at alkaline (pH 12) condition followed by HPH treatment (20, 40, 60, 80, 100 MPa) prior to neutralization at pH 7 was much better than that of HPH and/or pH shifting. The method carried out at under pH 12 followed by HPH 100 MPa was found to be the most efficient treatment for increasing the solubility of RDP from 0.86% to 63.50%, the emulsification from 3.13% to 7.10%, and the foaming capacity from 19.33% to 179.67%. It was revealed that pH shifting combined HPH treatment depolymerized the aggregates, reduced the particle size, spread the structure, decreased the surface hydrophobicity of RDP, and avoided any bitterness production. These results have important implications for the modification of proteins with improved functional profiles.