Self-assembled nanostructures from rice protein and its fractions: Molecular approaches, physicochemical principles, and functional applications

This review investigates the structural composition and physicochemical properties of rice protein (RP) and their functional applications, unraveling the molecular self-assembly approaches of rice protein isolates (RPI), rice protein hydrolysates (RPH), and their different fractions. RPI complexes with polysaccharides through both non-covalent (electrostatic, hydrogen bonding, hydrophobic and π-interactions) and covalent interactions (Schiff base and enzymatic reactions), whereas with polyphenols, it forms colloidal structures mainly through non-covalent forces. After enzymatic hydrolysis and chain segment reorganization, RPH exhibits enhanced interfacial activity and self-assembles into stable nanostructures, with applications in encapsulation and delivery of bioactive compounds. Owing to variations in conformation and amino acid composition, different fractions of RP can assemble into multilevel structures, including nanofibrils, branching clusters, and spherical nanoparticles, under specific environmental conditions. An in-depth exploration of these self-assembly principles can greatly enhance the physicochemical and structural properties of RP, thereby paving the way for a wide range of functional applications.