Co-assembly of rice and macadamia proteins for enhanced plant protein functionality: Fabrication, properties, and mechanism

Plant proteins are promising sustainable ingredients, but their use is limited by poor solubility and inadequate functionality. In this study, rice protein (RP) and macadamia protein isolate (MPI) were co-assembled to develop blended plant proteins with improved solubility and functional properties. Soluble RP-MPI composites were fabricated via co-assembly, primarily stabilized by hydrophobic interactions between unfolded polypeptide chains. At an RP/MPI ratio of 1:1, the composites showed optimal colloidal properties with the smallest particle diameter, lowest polydispersity index, and highest water dispersibility (94%), resulting in markedly improved emulsifying (120-fold) and foaming (3.2-fold) performance compared to RP alone. Moreover, the composites effectively stabilized oil-in-water emulsions with uniform droplet size distributions and showed a more complementary essential amino acid profile than the individual proteins. These results indicate that heteroaggregation of complementary proteins is an effective approach for improving the functional and nutritional quality of insoluble plant proteins.