Toward water-solvation of rice proteins via backbone hybridization by casein

Water insolubility is one of the major bottlenecks restricting the commercial availability of such food proteins as rice proteins (RPs), zein, etc. Here, we report that the structural hybridization of RPs and casein in a mass ratio of 1:0.01 can boost the solubility of RPs to over 90%. A structural analysis demonstrated that the backbones of the RPs and casein were integrated in basic solution (pH 12.0) and folded together into higher structures with subsequent neutralization. The hybrid backbones obtained improved the molecules' resistance to structural changes during neutralization, and formed protein bodies with appreciable exposed polar groups, which may have been buried in the absence of casein. Morphological observations confirmed the formation of well-defined nanoscale particles with no visible aggregation. Both proteins also retained their intact primary peptide chains, thus significantly protecting the original nature of the plant and animal derivatives.