Abstract: Objective: To explore the impact of ultra-high pressure (UHP) treatment on the Maillard reaction, and to develop a more efficient oil-water interface membrane for improving emulsion stability through protein-polysaccharide covalent complexation. Methods: The Maillard reaction between β-lactoglobulin (β-Lg) and chitosan (CS) at different mass ratios (1:1, 1:2 and 1:4) was initiated under dry-heating conditions after preprocessing at different pressures (200, 400 and 600 MPa). Their physical mixtures were used as a control for comparison. The resultant conjugates were characterized by the degree of browning, fluorescence spectroscopy, and circular dichroism spectroscopy, and the particle size, zeta-potential, and physical stability of the emulsions prepared with the conjugates were measured. Results: When the mass ratio of β-Lg to CS was 1:1 and 1:2, as the pressure increased, the degree of browning first increased and then decreased; when the ratio was 1:4, the degree of browning continued to increase. The fluorescence of β-Lg was quenched after the Maillard reaction, and the higher the CS ratio, the stronger the degree of quenching. The α-helix content of β-Lg was reduced from 19.5%, 21.1% and 22.5% to 18.7%, 16.9% and 15.9%, respectively after the Maillard reaction at β-Lg to CS ratios of 1:1, 1:2 and 1:4, and the α-helix content reached the maximum value of 19.6%, 19.0% and 16.6%, respectively under 400 MPa. The particle size (399.1, 481.5 and 584.4 nm) and 4 h turbiscan stability index (1.60, 2.31 and 0.49) of the emulsions prepared with the covalent conjugates were smaller than those with the physical mixtures, and the former had higher zeta-potential (46–48 mV). Conclusion: UHP-induced Maillard reaction had a positive effect on emulsion stability.

Key words: high pressure processing; β-lactoglobulin; chitosan; Maillard reaction