Structural and Physicochemical Characteristics of Rice Bran Dietary Fiber by Cellulase and High-Pressure Homogenization

The present paper aims to study the effect of cellulase hydrolysis and high-pressure homogenization on the structural and physicochemical properties of rice bran dietary fiber (RB-DF). Scanning electron microscopy showed that cellulase treatment led to the formation of a porous structure on RB-DF surface. High-pressure homogenization affected the laminated microstructure of RB-DF, leading to the formation of an irregular and loose surface structure. X-ray diffraction demonstrated that joint processing destroyed the amorphous hemicellulose and cellulose regions, and changed the crystallinity of RB-DF, albeit with a minor impact on the crystalline region of cellulose. Fourier transform infrared spectroscopy indicated that combined processing promoted dissociation of some glycosidic bonds in fiber structure, exposing the hydroxyl groups in cellulose, thus improving their ability to bind water molecules. Thermogravimetric analysis showed a significant decrease in the thermal decomposition temperature of RB-DF (p < 0.05) as well as a decrease in thermal stability after combined processing. Cellulase hydrolysis and high-pressure homogenization treatment did not improve their oil holding capacity, but significantly increased water holding capacity, swelling capability, and cation exchange capacity of RB-DF. Thus, enzymatic hydrolysis and high-pressure homogenization treatment can change the structure of RB-DF, exposing a large number of hydrophilic groups and enhancing hydration, obtaining uniform RB-DF particle.