Jukusei moromi

Mature moromi

End-stage moromi in which saccharification and alcoholic fermentation have both taken place sufficiently, and which has reached the desired balance of components, is called  mature moromi . At this stage, the rate of progression in the nihonshu-do and alcohol production has slowed down. Prolonged exposure to high levels of alcohol causes yeast to die, leading to a decline in quality. For that reason, the recent tendency is for joso (pressing) to take place as soon as possible after aru-ten. On the other hand, if young, immature moromi is pressed, this can lead to such off-aromas as kiga yo-shu and tsuwari-ka.

A method for determining the maturity (or otherwise) of moromi using declines in levels of pyruvic acid has been developed, and is used by some producers as a method for deciding the timing of the alcohol addition.