Optimization of bioethanol production from corn cobs by simultaneous saccharification and fermentation using response surface methodology

The present study was carried out to optimise the simultaneous saccharification and fermentation process for bioethanol production from corn cobs. Ten (10) different corn genotypes (hybrids) were characterized in terms of chemical composition, including total solid, moisture, cellulose, hemicelluloses, lignin and ash contents. Among different corn genotypes, milled cobs of corn genotype PMH10 were found to have significantly high cellulose (34.05%) and low lignin content (11.87%). With sodium hydroxide pretreatment, the relative proportion of cellulose (56.70%) increased, while that of hemicelluloses, lignin and ash substantially decreased (11.87, 8.61 and 0.6%) in the treated cob residues. The optimization of the simultaneous saccharification and fermentation (SSF) process of pretreated cob residues through response surface methodology showed that maximum ethanol concentration of 3.64 mg/mL could be achieved when SSF was performed at 28.58 FPU/g enzyme dosage, solid loading of 14.95% and yeast inoculum of 9.56%.