Ultrasonic-microwave assisted extraction of selenium-rich rice bran protein: A study on its structural and physicochemical properties

This study explores the effects of different 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 assessed for their efficiency and impact on protein structure, solubility, and functional properties, including emulsifying and foaming capacities. The results demonstrate that UMAE significantly enhances the functional properties of Se-RBP, achieving an emulsion stability index of 86.76% and a foaming capacity of 188.63%, both of which outperform the other methods. Furthermore, UMAE-treated Se-RBP exhibited a 35.43% increase in selenium bioavailability following gastrointestinal digestion. UMAE also delivered the highest antioxidant activity, reducing the IC 50 for DPPH radical scavenging to 0.85 mg/mL. These improvements are attributed to UMAE's ability to achieve a finer, more uniform particle distribution and increased exposure of bioactive compounds. This study reveals the potential of UMAE in optimizing the extraction and functional utilization of Se-RBP. • UMAE enhances Se-RBP's digestibility and antioxidant levels. • UMAE boosts Se-RBP's fat-holding and emulsion stability. • UMAE maintains Se-RBP's structural integrity and improves solubility. • Antioxidant activity significantly increased with UMAE. • UMAE and MAE provide uniform, smaller particle distributions.