Elucidating Deoiled Rice Bran as an Effectual Feedstock for Fermentation Through Mild Acid-Mediated Combined Pretreatment and Saccharification

Deoiled rice bran (DRB) is an agro-industrial residue of the rice bran oil processing industry that could be employed as a raw material for the fermentative production of valuable chemicals. The biochemical analysis of DRB revealed its major constituents as starch (24.06%, w/w), cellulose (23.55%, w/w), hemicellulose (15.54%, w/w), and lignin (3.93%, w/w). A combined pretreatment and saccharification process using mild H2SO4 was employed to extract maximum fermentable sugars from DRB. The treatment of DRB with 3% (v/v) H2SO4 at 90 °C (temperature) for 6 h (duration) and maintaining 1:8 (w/v) DRB:H2SO4 ratio (solid/liquid) is found to be the optimal condition to extract maximum monosaccharides. The maximum delignification observed was 78.86% (w/w). Glucose is the predominant sugar extracted, followed by xylose, mannose, and arabinose, respectively. The maximum sugar yield after detoxification was estimated to be 529.64 mg/g of DRB. The observed maximum percentage of reduction of cellulose and hemicellulose in the biomass after mild acid treatment was 79.24 and 84.62% (w/w), respectively. This study demonstrates the potential usage of agro-industrial waste DRB as a potential source for the fermentative production of greener chemicals.