Optimization of two-stage continuous ethanol fermentation using flocculating yeast

Summary Two-stage two-stream continuous ethanol fermentation using flocculating yeast was studied to produce high ethanol concentration from blackstrap cane-molasses. Optimizing pH, RQ, cell concentration, and medium molasses concentration of the first stage to give a good cell yield without a significant decrease in ethanol yield, the final ethanol concentration of as high as 92.0–93.5 g/l at an overall dilution rate of 0.10 l/h was obtained. This process could work stably as long as 3 weeks without any decreases in the efficiency.