We developed a new pretreatment process for producing high-efficiency bioethanol from a lignocellulosic
biomass. Barley straw was pretreated with sodium hydroxide in a twin-screw extruder for continuous
pretreatment. The biomass to ethanol ratio (BTER) for optimal pretreatment conditions was evaluated by
response surface methodology. Simultaneous saccharification and fermentation (SSF) was conducted to
investigate the BTER with 30 FPU/g cellulose of enzyme and 7% (v/v) yeast (Saccharomyces cerevisiae CHY
1011) using 10% (w/v) pretreated biomass under various pretreatment conditions. The maximum BTER
was 73.00% under optimal pretreatment conditions (86.61 ◦C, 0.58 M, and 84.79 mL/min for temperature,
sodium hydroxide concentration, and solution flow rate, respectively) and the experimental BTER was
70.01
±
0.59%. SSF was performed to investigate the optimal enzyme and biomass dosage. As a result,
maximum ethanol concentration and ethanol yield were 46.00 g/L and 77.36% at a loading pretreated
biomass of 20% with 30 FPU/g cellulose of the enzyme dosage for barley straw to bioethanol. These results
are a significant contribution to the production of bioethanol from barley straw.