Ultrasonic-Microwave Assisted Extraction of Selenium-Rich Rice Bran Protein: A Study on its Structural and Physicochemical Properties

Abstract

This study investigates the impact of various extraction methods on the physicochemical properties and functional performance of selenium-rich rice bran protein (Se-RBP). Four extraction techniques—alkaline extraction (AAE), microwave extraction (MAE), ultrasonic extraction (UAE), and ultrasonic-assisted microwave extraction (UMAE)—were evaluated for their efficiency and effect on protein structure, solubility, and functional properties including emulsifying and foaming capacities. The results indicate that UMAE significantly enhances Se-RBP's functional attributes, with notable improvements in emulsion stability index (ESI) reaching 86.76% and foaming capacity (FC) peaking at 188.63%, both superior to other methods. In terms of bioaccessibility, UMAE treated Se-RBP showed a 35.43% increase in selenium availability post-gastrointestinal digestion. Additionally, UMAE yielded the most potent antioxidant activity, reducing the IC50 for DPPH radical scavenging to 0.85 mg/mL. These enhancements are attributed to UMAE's ability to promote a finer, more uniform particle distribution and greater exposure of bioactive compounds. This study reveals the potential of UMAE in optimizing the extraction and functional utilization of Se-RBP.

Keywords: selenium-enriched rice, rice bran protein, extraction methods, physicochemical properties