Structural characteristics and emulsion stability of rice bran protein-chitosan complex: Effects of protein oxidation and ultrasonic treatment

Abstract

To enhance the emulsion stability of rice bran protein, rice bran was stored for 0-10 d to obtain rice bran protein with different extents of oxidation, and then rice bran protein-chitosan complexes were prepared using ultrasonic treatment (0-450 W). Compared to rice bran protein-chitosan without ultrasonic treatment and oxidative modification (zeta potential: 30.12 mV; creaming index: 61.11 %), appropriate ultrasonic treatment (ultrasonic power: 250 W) and moderate oxidative modification (rice bran stored for 3 d) synergistically enhanced the stability of rice bran protein-chitosan emulsions (zeta potential: 42.42 mV; creaming index: 15.16 %). The emulsion stability was highly correlated (P < 0.01) with the zeta potential (28.00-45.34 mV), size (1684.63-2428.79 nm), surface hydrophobicity (508.44-957.34), and protein flexibility (α-helix/β-sheet: 48.63-71.84 %) of the rice bran protein-chitosan complex. Overall, moderate protein oxidation combined with appropriate ultrasonic treatment could improve the emulsion stability by altering the structure of the rice bran protein-chitosan complex.

Keywords: Chitosan; Emulsion stability; Protein oxidation; Rice bran protein; Structural characteristics; Ultrasonic treatment.