Covalently cross-linked walnut protein-proanthocyanidin composite nanoparticles: Preparation, characterization, and...

This study fabricated walnut protein (WP)-proanthocyanidin (PC) composite nanoparticles via covalent cross-linking under alkaline aerobic conditions and evaluated their performance as stabilizers for Pickering emulsions. The physicochemical properties of WP-PC nanoparticles, as well as the functionality, rheology, in vitro digestion behavior, and storage stability of the corresponding emulsions, were systematically characterized. WP-PC (0.1%) exhibited the optimal performance: small particle size (127.3 nm), high surface charge (-10.36 mV), improved solubility, uniform spherical morphology, and enhanced thermal stability and antioxidant activity. The Pickering emulsions stabilized by WP-PC (0.1%) exhibited small droplet size (332.26 nm), low interfacial tension (13.05 mN/m), enhanced foaming properties, typical shear-thinning rheology, and favorable digestive stability (18.9% FFA release, 47.33% PC bioavailability), with no phase stratification during 5 days of storage. Overall, covalent conjugation of WP with 0.1% PC produces high-performance nanoparticles, and the emulsions stabilized by them show potential for application in functional foods as nutrient delivery vehicles.