Understanding of the mechanism of O/W & W/O/W emulsions stabilized by rice bran protein: Influence of concentration and localizations

Abstract

This study aimed to understand the effect of concentration of rice bran protein (RBP) on the stabilization mechanism of O/W_p, W_p/O/W, W/O/W_p and W_p/O/W_p emulsions. The characteristic of RBP at the oil-water interface, the physical properties, and the microstructure of emulsions were studied. It was found that the W/O/W structure had no positive effect on the stability of emulsions. When the concentration was 0.3%, 1.5% and 0.4%, respectively in O/W_p, W_p/O/W, and W/O/W_p emulsions, the stability was better than other emulsions in the same structure. The surface tension was 47 mN/m, 55 mN/m and 55 mN/m, and the zeta potential absolute value was 70, 53 and 48, respectively. CLSM showed that the RBP in the W_p/O/W emulsions was uniformly distributed. When the concentration was 1.5% in W_p/O/W, the RBP adsorbed percentage reached 95%, the electrostatic repulsion was strengthened (83.70), and the surface tension decreased to 42 mN/m. The emulsion had greater viscosity and better shear resistance with 1.5% RBP and could be used as a delivery medium. The study could not only make full use of rice bran but also provide experimental guidance for the basic study on encapsulation and non-allergenic emulsions.