Fabrication of soy protein amyloid fibril-chitooligosaccharide particles via covalent conjugation as an emulsifier and foam stabilizer for Pickering emulsion

The emulsifying properties of food proteins can often be enhanced by covalent conjugates with carbohydrates, meeting the safety and functionality requirements for Pickering emulsions in industries such as food, pharmaceuticals, and cosmetics. This study aimed to covalently link soybean protein amyloid fibrils (SAFs) and chitooligosaccharides (COSs) using genipin as a natural cross-linker and with the assistance of ultrasonic treatment (400 W, 5 min) to prepare novel protein-based emulsifiers. The effects of pH value and SAF:COS mass ratio on the microstructure, physicochemical properties, and emulsifying/foaming properties of these composite nanoparticles were systematically investigated. The optimal preparation conditions were determined to be a pH of 7 and a mass ratio of 1:2 (SAF:COS). The foams stabilized by the nanoparticles prepared under these conditions possess excellent plasticity, while the corresponding Pickering emulsions exhibit high encapsulation efficiency (83.9%) for β-carotene and remarkable storage stability. These research results indicate that genipin-crosslinked nanoparticles can serve as effective emulsifiers and foaming agents, capable of protecting hydrophobic nutrients and thus facilitating their wider application in commercial products. • Protein-based nanoparticles were fabricated via genipin crosslinking with ultrasound assistance. • Genipin mediated robust covalent conjugation enhances stability for food grade emulsifiers/foam stabilizers. • Covalently-compounded nanoparticles enhance the encapsulation efficiency of β-carotene significantly. • Pickering emulsions stabilized by covalent nanoparticles demonstrate excellent rheological properties and phase-separation resistance.