Fernanda Airoldi Colombo

Corn stover (CS) is a promising feedstock for producing fermentable sugars (FS) and ethanol due to its high holocellulose content. This study investigated the enhancement of FS production via enzymatic hydrolysis (EH) following steam explosion (SE) pretreatment of CS, aiming to improve ethanol yields through alcoholic fermentation. SE was conducted at 160 °C, 180 °C, and 200 °C for 2.5 and 10 min. EH was performed using 15 and 30 filter paper unit (FPU) enzyme loadings and 1% and 2% (w/w) substrate concentrations, applied to both untreated CS and pretreated CS (PCS). Fermentations with Saccharomyces cerevisiae were carried out at 30 °C and 120 rpm. The optimal SE condition (200 °C, 10 min) yielded 4.25 g of total sugars per 100 g CS. Under 30 FPU and 2% PCS, EH yielded 41.57 g/100 g PCS and 18.51 g/100 g CS. The combined SE + EH process reached 45.82 g/100 g PCS, about 2.5 times more than EH alone. The highest ethanol concentration and production rate were 15.54 g/L and 1.30 g/L·h, with a yield of 0.47 g/g. Under optimal conditions, fermentation achieved a conversion efficiency of 92.33%.