Optimization of Physical Force-Assisted Alkaline Extraction of Rice Bran Protein

This study comparatively evaluated the efficiencies of alkaline extraction, colloid milling-assisted alkaline extraction, ultrasonic-assisted alkaline extraction, and colloid milling, ultrasonic-assisted extraction for the extraction of rice bran protein(RBP) with respect to RBP yield and purity. It was shown that a significantly increased extraction yield and a RBP purity of 74.27% were obtained by the colloid milling, ultrasonic-assisted extraction method. In this method, the extraction parameters ultrasonic power, solid-to-solvent ratio, temperature and extraction time were optimized by response surface methodology using the Design Expert 8.0.6. The optimum extraction conditions for maximizing RBP yield were determined as 40 mesh, 9, 69 W, 4 s, 2 s, 20:1(mL/g), 40 min and 46 ℃ for rice bran granularity, pH, ultrasonic power, working time, intermittent time, solid-to-solvent ratio, ultrasonication time and extraction temperature, respectively. The predicted extraction yield of RBP was 92.14%, agreeing with the experimental value(90.84%). The colloid milling, ultrasonic-assisted extraction method could significantly increase the extraction yield of RBP and shorten the extraction time and thus could provide a foundation for for further study of rice bran protein.