Chemical composition, structure, physicochemical and functional properties of rice bran dietary fiber modified by cellulase treatment

Abstract

Rice bran dietary fiber (ERBDF) subjected to pre-water-washing and complex enzyme treatment using heat-stable α-amylase, alcalase, and glucoamylase had significantly higher (p < 0.05) proportions of cellulose, hemicellulose, lignin, and lower proportions of lipid, protein, and starch than rice bran dietary fiber subjected to complex enzyme treatment without pre-water-washing. Cellulase modification of ERBDF significantly decreased (p < 0.05) cellulose, hemicellulose, starch, and protein contents while the relative lignin content increased. Cellulase modification significantly improved (p < 0.05) water-holding capacity, oil-holding capacity, swelling capacity, cholesterol absorption capacity, and glucose adsorption capacity, while decreasing the emulsifying capacity and glucose dialysis retardation index. The changes of physicochemical and functional properties of fiber samples after cellulase modification were attributed to the increased porosity of the fiber surface, greater exposure of binding sites caused by reduced crystallinity, and changes to the chemical composition.

Keywords: Cellulase; Chemical composition; Crystalline structure; Dietary fiber; Micro-structure; Rice bran; Thermal stability.