A sequential approach of alkali enzymatic extraction of dietary fiber from rice bran: Effects on structural, thermal, crystalline properties, and food application.

Abstract

This study optimized the extraction of soluble and insoluble dietary fiber from defatted rice bran (DRB) using an alkali-enzymatic approach with response surface methodology. Key variables included substrate concentration (5–30%), enzyme dose (1–50 µL/g), and processing duration (2–12 h). The highest fiber yields—2% soluble dietary fiber and 59.5% insoluble dietary fiber—were achieved with 50 µL/g cellulase-AC enzyme after 24 hours. FTIR and SEM analyses confirmed that enzymatic hydrolysis of higher-order polysaccharides and disruption of intramolecular hydrogen bonds between oligosaccharides and the starch matrix contributed to improved yields. Structural and thermal properties of the extracted fibers were characterized. When incorporated into rice porridge, sensory evaluation via fuzzy logic analysis assigned the highest scores to formulations containing 0.5% insoluble and 1.25% soluble dietary fiber.

Mechanism

Cellulase-AC enzyme hydrolyzes higher-order polysaccharides and disrupts intramolecular hydrogen bonds between oligosaccharides and the starch matrix, thereby increasing dietary fiber extraction yield from defatted rice bran.