Achieving high ethanol yield by co-feeding corncob residues and tea-seed cake at high-solids simultaneous saccharification and fermentation

Abstract

The feasibility of high-solids simultaneous saccharification and ethanol production was investigated using unwashed corncob residues (CRs) with tea-seed cake (TSC). Tea saponin of TSC could serve as an accelerant to enhance ethanol production and reduce the dosage of enzymes. The proteins of TSC could be the nitrogen resource for yeast. The effects of substrate concentration (10%, 15%, and 20% (w/w)), enzyme dosage (2.5–15 FPU/g-cellulose), and types of media on ethanol production were evaluated. An ethanol yield of 86.56% of the theoretical maximum could be obtained at a substrate concentration of 15% (w/w) with 10 FPU/g-cellulose. Furthermore, fermentations in different media showed that the surface tension (49.21 mN/m) and contact angle (42.6°) of the fermentation system with TSC were lower than those from the other systems. This study found that adding TSC to the fermentation system was an attractive strategy to achieve high ethanol yield without any pretreatment. Comprehensive utilization of CRs and TSC as feedstocks for ethanol production can reduce the cost of biorefineries with environmental benefits.