Kassei Shu

Kasseishu is a type of sake in which the moromi (fermentation mash) is lightly strained rather than pressed, and then bottled while fermentation continues inside the bottle. The fermentation produces carbon dioxide, giving the sake its characteristic bubbles and gentle effervescence. Also called kassei seishu (active sake), it has a cloudy white appearance, and the activity of the yeast brings out a fresh, refreshing flavor. However, because fermentation continues, pressure can easily build up inside the bottle, so care is needed when opening it. For this reason, particular attention must be paid to how it is stored and handled.