Effects of Hexametaphosphate on Soybean Pectic Polysaccharide Extraction

Abstract

The effects of sodium hexametaphosphate concentration, incubation temperature, and pH on the extraction of polysaccharide from soybean okara (soybean curd waste) were examined. The results suggest that the soybean polysaccharides were almost completely extracted with 50 times their volume of a 2% hexametaphosphate solution at 100°C for 2 h, avoiding protein contamination. The viscosity, molecular weight, and sugar composition of the polysaccharides were compared with those of the commercially available samples. No differences were observed in the molecular weight or neutral sugar composition. However, it was found that the galacturonate distribution in the molecules of the two polysaccharides was different. The viscosity of the polysaccharide solution was changed by adding small amount of salt.