Black rice bran (BRB) is a nutrient-dense byproduct rich in natural unsaturated fatty acids and health-promoting anthocyanins, notably cyanidin-3-O-glucoside (C3G). However, its utilization is limited by rapid lipid rancidity, driven by endogenous lipases, and the degradation of anthocyanins during processing or storage. This study aimed to optimize a twin-screw extrusion process to simultaneously enhance BRB's shelf stability and preserve its bioactive compounds by using (L 9 3 4 ) orthogonal design and principal component analysis (PCA), and extrusion parameters (temperature, water feed, screw speed) were optimized. The optimal condition (140°C, 14%, 180 rpm) effectively inhibited lipase activity by approximately 76.52% and retained about 61.21% of the initial C3G content. Crucially, E-BRB extract retained the key bioactivities of untreated BRB, comparably inhibiting pro-inflammatory factors (IL-6, NO, TNF-α) and enhancing antioxidant enzymes (SOD, CAT, GSH-Px) in LPS-stimulated macrophages via the TLR4 and Nrf-2/HO-1 pathways. Furthermore, E-BRB exhibited significantly improved storage stability, maintaining low acid and peroxide values over 90 days. These findings demonstrate that optimized extrusion is an effective strategy for stabilizing BRB, preserving its health-promoting potential, and facilitating its application in functional foods.
Zhao et al. (Fri,) studied this question.