Preparation of Rice Bran Protein Solutions Using a Water-Based Extraction Process

Rice bran (RB), which is a waste product of the rice industry, has great potential for use as a source of new protein supplements. In this study, the extraction of soluble proteins from rice bran was conducted using a water-based extraction method with the aid of sonication extraction and a hybrid sonication/thermal treatment approach, known as the soni-auto hybrid method. Both extraction methods were explored and compared to determine the most efficient extraction process using the one-factor-at-one-time (OFAT) method. The parameters studied and their experimental ranges for both extraction methods were as follows: sonication time = 5-45 min, sonication temperature = 30-80 degrees C, and feed-to-solvent ratio = 1:5-1:80 (g:mL). The most efficient extraction method was then used for optimization by means of response surface methodology (RSM) based on the central composite design (CCD) model. It was found that the soni-auto hybrid method exhibited a superior extraction performance compared with sonication alone, wherein the protein concentration was increased by up to 18% while maintaining a comparable quality. The use of this hybrid treatment approach also reduced the sonication time from 35 to 30 min and the sonication temperature from 50 to 45 degrees C. The optimal soni-auto hybrid conditions were determined by RSM to be a temperature of 50 degrees C, a feed-to-solvent ratio of 1:20, and an extraction time of 30 min; these conditions produced a protein concentration of 17.174 mg/mL. Finally, evaluation of the surface morphology and functional groups on the protein confirmed that the hybrid soni-auto approach provided a higher protein concentration without significantly affecting the protein structure or quality.