Complexation of rice proteins and whey protein isolates by structural interactions to prepare soluble protein composites

The main factor limiting the preparation of high value-added rice proteins (RPs) is their low solubility. In this experiment, whey protein isolates (WPIs), which are of high nutritional value, were compounded with RPs at pH 12, and formed RP-WPI complexes by neutralization to pH 7 (pH-cycle). The formation of the protein complexes was studied by fluorescence and ultraviolet (UV) spectra. The results showed that hydrogen bond, hydrophobic force and electrostatic interaction mediated the merging of the two proteins into particulate spheres. Meanwhile the complexes acquired considerable surface charges resisting aggregation of the protein bodies, and the solubility of RPs was increased to more than 50%. The effectiveness of protein interactions by pH-cycle used in this study indicated that the technique may be a versatile approach to improve the functional properties of food proteins.