Rice bran is rich in proteins with high nutritional values. However, current protein extraction methods from rice bran are greatly limited by their low yield. Therefore, in this study, we aimed to develop a feasible method to extract rice bran protein (RBP) of high purity and quality. We prepared RBP using low-heat-treated defatted rice bran (LDRB) and analyzed its functional properties. The protein solubility of LDRB increased from 25.4% to 56% upon increasing the pH level and was more than double that of heat-stabilized defatted rice bran. RBP prepared from LDRB had good functional properties, comparable to those of soy proteins. The emulsifying capacities of RBP were 424 ± 14 mL/g at pH 4 and 530 ± 21 mL/g at pH 7.0. Under acidic conditions, RBP showed a better emulsifying capacity than soy proteins (262 ± 1 mL/g at pH 4). RPB showed water-binding and oil-absorption capacities of 270 ± 35 g/100 g and 268 ± 30 g/100 g, respectively. Moreover, RBP showed better foaming capacity (610% vs. 590%) and foam stability (83% vs. 4%) than soy proteins; however, it lacked gelling properties. This study demonstrated that RBP is a potential new protein source in the food industry.
Keywords: functional properties; low-heat treatment; protein isolates; rice bran.