Conversion of rice husks into antioxidative and prebiotic biomaterials using subcritical water pretreatment and cellulase incubation under high-pressure

This study investigated the combined effects of subcritical water (SW, 170 °C) pretreatment and cellulase incubation under high-pressure (HP, 200 MPa) on the hydrolysis efficiency of rice husks (RH) and explored the antioxidative and prebiotic activities of the RH hydrolysates. The SW pretreatment disintegrated the cell wall of RH, increasing the brix and reducing sugar content. RH hydrolyzed by cellulase exhibited greater antioxidative activity than that before enzymatic treatment. Particularly, the antioxidative activity of RH hydrolysates incubated under HP was higher than those incubated under atmospheric pressure (AP), regardless of SW pretreatment. Although SW pretreatment reduced the prebiotic potential of RH hydrolysates, RH hydrolyzed under HP without pretreatment exhibited greater prebiotic potential for Lactobacillus rhamnosus GG (LGG) than that hydrolyzed under AP incubation. The results demonstrated that SW pretreatment and HP incubation have potential applications for producing bioactive substances using RH, and optimization of the process parameters warrants further exploration.