Ethanol Blending in Rice (Oryzae sativa L.)

The global demand for renewable energy has accelerated the exploration of bioethanol as a sustainable alternative to fossil fuels. Ethanol blending in transport fuels reduces greenhouse gas emissions, enhances energy security, and supports climate mitigation goals. Traditionally, sugarcane and maize have been the dominant feedstocks, but rice particularly surplus grains, broken rice, and rice straw has emerged as a promising option due to its abundance in Asia (Awasthi et al., 2020). Rice straw, a major agricultural residue, contains a complex lignocellulosic matrix suitable for bioethanol production. Pretreatment methods such as acid or alkaline hydrolysis and steam explosion improve cellulose accessibility, followed by enzymatic hydrolysis using cellulases and amylases to release fermentable sugars. Fermentation with Saccharomyces cerevisiae or engineered yeasts then converts these sugars into ethanol under controlled anaerobic conditions (Soleymani et al., 2021). Broken rice, with its high starch content, is particularly efficient for hydrolysis, yielding glucose that can be rapidly fermented (Verma et al., 2021).