Abstract: Soy protein isolate (SPI)-dextran conjugates (CON) were prepared through Maillard reaction in solution under macromolecular crowding environment, then fractionated by their solubility at pH 4.5 (MC45) and pH 6.5 (MC65), and characterized. SDS-PAGE and molecular weight distribution of the conjugates showed typical patterns of conjugate formation and different characteristics between MC45 and MC65. The effects of pH, heating temperature and the addition of NaCl on the properties of emulsions stabilized with SPI-dextran conjugates were examined using a light-scatter particle size analyzer and a Zeta-potential analyzer. Results showed that in an acidic environment the average droplet size (d43) of the emulsion with MC45 was 10 μm, lower than that of the emulsion with MC65, and was little affected by ion concentration and temperature. Compared with native protein, SPI-dextran mixture and MC45, MC65 had better curcumin loading capacity with respect to loading amount (30.21 μg/mg) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity (18.33% DPPH scavenging) and resulted in larger particle size.

Key words: soy protein isolate, dextran, macromolecular crowding, emulsifying property, carrier