Development of efficient shochu production technology with long-term repetition of sashimoto and reuse of stillage for fermentation

In traditional shochu production with a long-term repetition of sashimoto, the activity of yeast cells decreases, generally resulting in bacterial contamination problems. In this study, a pilot scale study was carried out to demonstrate a technique developed with a laboratory scale test, which improved the activity of the yeast in the first-stage fermentation and the possibility of reuse of stillage for the fermentation to reduce the quantity of stillage from the distillation by 50%. The yeast cells were activated by aeration and stirring for several hours after sashimoto. The yeast cells maintained a high activity level during the entire test period. The ethanol concentration of the second-stage fermented mash was improved and an ethanol concentration of more than 17.5% (v/v) was achieved when stillage was reused in place of water for the fermentation. Comparing the flavour compounds of shochu produced by the traditional process with the long-term repetition of sashimoto, 0.2 ppm of furfural was detected in the,shochu produced from the stillage reuse process. No other significant differences were found in the concentrations of the low-, middle- and high-boiling flavour compounds examined, nor in the concentrations of isoamyl acetate and beta-phenethyl acetate, which are desired flavour compounds in shochu.