A water-saving fermentation process for sorghum grain: The effect of re-using stillage liquid part on ethanol efficiency and volatile compounds

This study investigates the effect of re-using the liquid fraction of stillage on the ethanol yield and distillate quality during sorghum fermentation. Forty percent of the water in the mashing process was replaced by the thin fraction of stillage from the previous fermentation. Fermentation processes from ten subsequent cycles were evaluated. The results show that re-using the liquid stillage did not cause any disturbance in ethanol fermentation, and the re-using had a positive effected on ethanol yield and on the quality of raw distillates. By the tenth cycle, the ethanol yield had increased by 6%-9% over the first cycle without re-using, for five sorghum cultivars. It was also assumed that re-using the liquid stillage led to less accumulation of volatile compounds in the raw distillates. (c) 2020 Elsevier Ltd. All rights reserved.