Optimization of Rice Bran Protein Extraction via Microwave-Assisted Alkaline Method for Drug Delivery Applications using Response Surface Methodology

Abstract

Rice bran, a by-product of rice milling, contains 10%–16% protein, 15%–22% lipids, and 7%–11.4% fiber. Rice bran protein (RBP) is hypoallergenic and has shown potential in cancer prevention, making it valuable for food and pharmaceutical applications. This study extracted RBP using microwave-assisted alkaline extraction in a shorter time for potential pharmaceutical applications, with or without modification. Response surface methodology (RSM) was used to optimize four parameters: microwave power, extraction time, pH, and solvent-to-defatted rice bran (DRB) ratio. The optimal extraction conditions were determined as 200 watts for 150 s at pH 12, with a solvent-to-DRB ratio of 5:1 (v/w). Under these conditions, the predicted RBP recovery was 47.60%, while the actual recovery was 47.76%, validating the optimization model. The recovered RBP concentrate (RBPC) had a particle size of approximately 285.13 nm, a polydispersity index of 0.33, and a zeta potential of -33.33 mV, indicating good electrostatic stability against coalescence and flocculation. Additionally, SDS-PAGE analysis revealed that glutelin was the predominant protein fraction in the RBPC, confirming the efficiency of the extraction method in isolating specific protein fractions. These findings demonstrate that microwave-assisted alkaline extraction is an effective approach for enhancing RBP recovery while maintaining its stability and making it suitable for pharmaceutical applications.