Physicochemical properties of soy protein isolates-acacia gum conjugates

Abstract

Protein-polysaccharide conjugates were generally prepared by dry-heating. However, it was time-consuming and the sample gained was inhomogeneous. A faster way of preparing protein-polysaccharide conjugates is needed. Accordingly, soy protein isolates (SPI)-Acacia gum (GA) conjugates prepared by the wet-heating method were studied in the present work. Physicochemical properties of SPI-GA conjugates were also determined. The results showed that the wet-heating method could improve the rate of the graft reaction of protein and polysaccharide. The solubility of SPI-GA conjugates was significantly (P < 0.05) higher than that of unreacted SPI-GA mixtures and SPI at the same pH values. The emulsion activity index (EAI) of the grafted SPI increased remarkably. Moreover, a significant (P < 0.05) improvement on the emulsifying stability index (ESI) was observed and emulsions with a smaller droplet size were obtained. No visible flocculation during extended storage (30 days) was observed. The time course of the development of the graft reaction of SPI with GA was also shown by SDS-PAGE.