Sake brewing was carried out with a temperature-sensitive autolysis mutant (gal-31 strain) isolated from sake yeast Kyokai No.7. It was possible to control the fermentation of sake mash (
moronmi) made by the gal-31 strain by a heat treatment at 37°C for 1 hour, which was the limit of treating condition for maintaining the quality of
moronmi. The storage of the gal-31 strain
moronmi at low temperature (12-15°C) for 2 days or more after heat treatment induced the increase in the yeast lethal rate. The heat treatment and post fermentation method resulted in the acceleration of the leakage of yeast content and the decrease in pyruvate content in the
moronmi. The sake brewed with this method had a better quality than those obtained by normal brewing method or the method in which only heat treatment was applied. Furthermore, the method was applied to other fermenta -tion system
i. e., sake
moronmi liquefied or saccharified before mashing. As the result, it was possible to brew soft type sake of high quality by each fermentation system.
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