Development of Efficient Shochu Production Technology with Long-term Repetition of Sashimoto and Reuse of Stillage for Fermentation

摘要

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 β-phenethyl acetate, which are desired flavour compounds in shochu.