Convection (tairyu)

Convection (tairyu) refers to the movement that occurs within a liquid or gas as a result of temperature differences. In sake brewing, it is particularly important during fermentation. For example, the heat generated by yeast raises the temperature within the shubo (yeast starter) and the moromi (fermentation mash). The surrounding liquid expands and becomes lighter, causing it to rise. As it rises, fresh liquid is drawn in from below, which promotes efficient yeast activity and the supply of nutrients. In this way, convection contributes to improving the quality of sake.