Optimization of the Extraction Process and Physico-chemical Properties of Soluble Dietary Fiber from Defatted Rice Bran

Abstract

Ultrasonic-assisted extraction was employed to obtain soluble dietary fiber (SDF) from defatted rice bran. Response surface methodology (RSM) was conducted to investigate and optimize the effects of solid-liquid ratio, amplitude, and ultrasonic time on the extraction. The optimal conditions were determined as an ultrasonic time of 19 min, an amplitude of 20%, and a solid-to-liquid ratio of 1:14 (g/mL), achieving an actual extraction yield of 14.3%. Under these conditions, the SDF exhibited enhanced water-holding (3.21±0.03 g/g), oil-holding (1.78±0.02 g/g), swelling (2.03±0.02 mL/g), solubility (0.82±0.02 g/g), glucose adsorption capacity, and cholesterol adsorption capacity properties compared to untreated rice bran dietary fiber, facilitating its processing and utilization. Laser particle size analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction revealed that ultrasonic treatment caused the SDF to expose more chemical groups, strengthen intermolecular hydrogen bonds, and transform into a rough, porous structure with numerous wrinkles. Overall, ultrasound was shown to effectively improve the physicochemical and functional properties of defatted rice bran SDF, offering a theoretical foundation for its extraction and application.