Potential of Bran from Two Varieties of Rice (Oryza) Spp for Bioethanol Production

Abstract

Second generation ethanol is produced from non-food based including waste from food crops, wood chips and agricultural residue. Lignocellulosic and starchy materials in them are converted to fermentable sugars which are further processed to produce bioethanol. Rice bran is an agricultural residue with abundant carbohydrate for bioconversion into ethanol. This study was designed to evaluate the potential of two varieties of rice bran (Sipi and Wita) to produce bioethanol. Compositional analysis of Wita rice bran showed 40% cellulose, 23% hemicellulose and 16% lignin content. Sipi variety contains 35% cellulose, 27% hemicellulose and 13% lignin content. Sodium hydroxide pretreatment was carried out at different concentrations (0.5%, 1%, 2% and 3%) and residence time of (15, 30, 60, and 90min). It was observed from the present study, pretreatment of rice bran with 2% NaOH for 90min is considered as effective pretreatment condition for bioethanol production from rice bran. Simultaneous saccharification and fermentation of cellulosic biomass was carried out for 72h with Saccharomyces cerevisae and Mucor indicus. Fermentation of Wita variety with S.cerevisiae produced highest bioethanol yield of 1.36% while Mucor indicus produced 0.75% bioethanol yield. From the result of these findings, it can be concluded that rice bran could be considered as a promising substrate for the fermentation of second generation ethanol.