Optimization of Rice Bran Protein Extraction: Green Approaches using Deep Eutectic Solvents and Microwave-Assisted Extraction Techniques

Abstract

A novel approach for green protein extraction was developed by combining deep eutectic solvents (DES) and microwave-assisted extraction (MAE) to optimize the extraction of protein from defatted rice bran (DRB). Rice bran, an agricultural byproduct, is rich in proteins and bioactive compounds; however, it remains largely underutilized due to the inefficiency of current extraction methodologies. Rice bran protein (RBP) is widely known for its hypoallergenic properties and nutritional benefits. The present study examined various DES types (choline chloride-based mixtures with different hydrogen bond donors: glycerol (neutral), oxalic acid (acid), and urea (base)) to extract protein from rice bran protein with microwave heating. The extraction efficiency was evaluated using different microwave power, extraction time, and sample-to-DES ratios. Key factors controlling the extraction and optimal operating conditions were optimized by response surface methodology to obtain the highest protein extracted from rice bran which was indicated by protein recovery. The extraction parameters that were determined to be optimal were as follows: a choline chloride-urea DES, a solvent-to-sample ratio of 5.79, microwave power of 296.97 W, and 44.75 s of extraction time. The optimization of protein extraction was characterized using a Box-Behnken Design of Experiment, with protein recovery as the response. The quality of the protein was then analyzed using SDS PAGE for molecular weight distribution. The selected DES-MAE method achieved a maximum protein recovery of 39.96 ± 0.5%. This combined DES-MAE technique offers a promising, environmentally friendly alternative for efficient RBP extraction.