Hot-compressed water extraction of polysaccharides from soy hulls

The polysaccharides of soy hulls were extracted by hot-compressed water at temperatures of 110 from 180 °C and various treatment times (10-150 min) in a batch system. It was determined that a moderate temperature and short time are suitable for the preparation of polysaccharides. The structure of xylan and the inter- and intra-chain hydrogen bonding of cellulose fibrils in the soy hulls were not significantly broken down. The polysaccharides obtained were primarily composed of α-l-arabinofuranosyl units, 4-O-methyl-glucuronic acid units and α-d-galactose units attached with substituted units. A sugar analysis indicated that arabinose was the major component, constituting 35.6-46.9% of the polysaccharide products extracted at 130 °C, 140 °C, and 150 °C. This investigation contributes to the knowledge of the polysaccharides of soy by-products, which can reduce the environmental impact of waste from the food industries.