Physicochemical properties of pronase-treated rice glutelin

Rice glutelin protein was extracted from defatted medium-grain rice by alkali extraction followed by acid precipitation. Extracted glutelin was hydrolyzed with Pronase E, a bacterial protease, and the functional properties of hydrolysates were evaluated. Nitrogen solubility of pronase-treated glutelin protein increased from pH 2 to pH 12. Similarly, foaming and emulsion properties of hydrolyzed protein also showed im; proved characteristics. The emulsion activity, expressed as the turbidity of diluted emulsions, was significantly greater (P less than or equal to 0.05) for hydrolyzed samples. However, turbidity for all samples decreased with increased homogenization time, indicating a decrease in the volume of dispersed oil. There were significant changes in apparent viscosity as a function of shear rate, with viscosity decreasing with increasing shear rate. The viscosity of dispersions of all hydrolyzed samples was significantly lower than that of the native sample at all shear rates tested. Enzymatic hydrolysis of rice endosperm storage glutelin proteins appeared to improve the functional characteristics of the hydrolyzed proteins.