Modulation of walnut protein solubility: effects of multiple modification treatments on walnut protein structure, physicochemical properties, and investigation of mechanisms

Abstract

In this study, we proposed a targeted modification technique of ultrasound-assisted restriction enzyme digestion combined with glycosylation, which could significantly improve the solubility of walnut protein (WP, +91.63 %). The mechanism was elucidated by spectral analysis and molecular docking: ultrasound changed the conformation of WP to promote enzymatic degradation, which led to deeper grafting of maltodextrin (MD); hydrogen bonding and hydrophobic interaction dominated the WP-MD binding, which synergistically altered the tertiary structure of the protein, reduced the degree of aggregate denaturation, and restructured the protein-water environment equilibrium. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, etc., confirmed that the multistage treatment synergized the effect through physicochemical and molecular interactions. This study provides a theoretical basis for enhancing the solubility of plant proteins, expands the application of WP in food emulsions and other fields, and lays the foundation for the development of highly stable plant-based food products by directional modification technology.

Keywords: Functional properties; Molecular interaction; Physical and chemical properties; Solubility; Walnut protein.