For diversification of sweet potato
shochu quality, we carried out
shochu brewing using a mixed culture of two yeast strains. Although using the same amount of each yeast as a fermentation starter, the ratios of each yeast were greatly changed in the first
moromi. The ratios ranked from highest to lowest in an order from Kagoshima No.5, No.4, No.2, and Ko-CR-37. The ethanol tolerance, volatile compounds, and sensory evaluation changed depending on the ratios of each yeast in the
moromi. We confirmed that a mixed-culture fermentation diversified sweet potato
shochu quality in a full-scale test. As there was a high concentration of citric acid in the
koji extract medium, differences in the growth rates of each yeast increased. This result indicated that the differences in growth rates caused changes in the ratios of each yeast in the
moromi. We also confirmed that it was necessary to ferment from the second
moromi or without
sashimoto in order to stabilize the ratios of each yeast and
shochu quality.
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