Physicochemical properties of pronase-treated rice glutelin

Rice glutelin protein was extracted from defatted medium-grain rice by alka li extraction followed by acid precipitation. Extracted glutelin was hydrol yzed with Pronase E, a bacterial protease, and the functional properties of hydrolysates were evaluated. Nitrogen solubility of pronase-treated glutel in protein increased from pH 2 to pH 12. Similarly, foaming and emulsion pr operties of hydrolyzed protein also showed im; proved characteristics. The emulsion activity, expressed as the turbidity of diluted emulsions, was sig nificantly greater (P less than or equal to 0.05) for hydrolyzed samples. H owever, turbidity for all samples decreased with increased homogenization t ime, indicating a decrease in the volume of dispersed oil. There were signi ficant changes in apparent viscosity as a function of shear rate, with visc osity decreasing with increasing shear rate. The viscosity of dispersions o f all hydrolyzed samples was significantly lower than that of the native sa mple at all shear rates tested. Enzymatic hydrolysis of rice endosperm stor age glutelin proteins appeared to improve the functional characteristics of the hydrolyzed proteins.