Improvement of the functional properties of sorghum protein by protein-polysaccharide and protein-protein complexes

Abstract

Sorghum protein was conjugated with dextran or galactomannan under controlled conditions (60 °C, 79% relative humidity), or cross-linked with transglutaminase (TGase) to improve the functional prop-erties. SDS-PAGE patterns showed that the conjugated and cross-linked proteins had higher molecular mass bands above the stacking gel. Although sorghum protein and its polysaccharide mixture were insoluble at pH 4 — 6, the polysaccharide conjugates were soluble at all level of pHs, despite being composed of higher molecular sizes. Heat stability of the polysaccharide conjugates was greatly improved in that there were no turbidity at 100 °C, while TGase-treated samples sup-pressed heat-induced aggregation up to 60 °C. The emulsifying proper-ties of the polysaccharide conjugates and TGase treated sample were also greatly improved.