Rice proteins and cod proteins forming shared microstructures with enhanced functional and nutritional properties

•Protein co-assemblies were prepared using rice proteins and cod proteins.•The solubility of rice proteins increased from 1.7% to 92.7%.•The co-assembled proteins acquired leveraged amino acid compositions. Low water solubility strictly limits the potential applications of plant or animal proteins such as rice proteins (RPs) and cod proteins (CPs). In this study, nanoscale hydrophilic colloidal co-assemblies (80 ~ 150 nm) with excellent water solubility were prepared by hydrating RPs and CPs at pH 12 combined with neutralization. The solubility of RPs was boosted to over 90% (w/v), while most of the subunits in CPs became fully soluble. Structural analysis revealed that RPs and CPs non-covalently reacted, which triggered sheet-helix transitions and formed a compact core of RPs coated by a layer of CPs. Both proteins exposed significant hydrophilic motifs and buried hydrophobic moieties, contributing to the high water-dispersibility of their co-assemblies. Moreover, the co-assembled proteins acquired leveraged amino acid compositions between RPs and CPs. This study will enrich the processing technology of protein components, customizing their structural and nutritional characteristics.