Mixed fermentation of corn and pretreated corn stover for fuel ethanol production

Background and objectives Fuel ethanol is almost exclusively produced from corn with minor contributions from other cereal grains. Cellulosic ethanol production has significant potential as well as serious limitations. This study proposed that pretreated corn stover could be simultaneously converted and fermented with corn in existing ethanol facilities. Findings Mixed fermentation ethanol yields increased significantly relative to the control fermentations. Incorporation of 5% pretreated corn stover increased ethanol yields by 12.7% with 10% corn mash and 11.9% with 20% corn mash over corn only control fermentations. Using 20% corn, residual xylose and arabinose were 0.072 and 0.023 grams/gram biomass, respectively, indicating addition ethanol potential with a C5 fermenting yeast. DDGS color and lipid contents were negatively impacted; however, the nutrient value of the corn portion is unlikely to be altered. Conclusions Direct incorporation of pretreated corn stover into the corn ethanol process can be done with little or no reduction in corn or stover conversion efficiency. Significance and novelty This study demonstrates clearly that pretreated biomass can be efficiently co-fermented with corn to produce cellulosic ethanol in yields approximating those from biomass alone and eliminates many of the significant economic and processing issues that stand-alone cellulosic ethanol facilities face.