Motowake (dividing the yeast starter to cool it)

Motowake is a step in sake production carried out once the shubo (yeast starter) has fermented sufficiently and the yeast has multiplied. At this point the alcohol content has reached 8-10% and the acidity has also risen, so if the shubo were left at a high temperature, the yeast could weaken or die. To prevent this, the shubo is divided among several shallow tubs such as hangiri-oke (wide, shallow wooden tubs) so that its temperature drops, helping to keep the yeast healthy. In recent years, a more efficient method called maru-zamashi ("whole cooling") has become common, in which the shubo is cooled in its original tank using a cooling device. Motowake is thus a traditional technique and one of the important ways of protecting the yeast in sake brewing.