Heat of vaporization (kikanetsu)

Heat of vaporization (kikanetsu) refers to the amount of heat a liquid absorbs when it evaporates. This phenomenon is particularly important in sake production. When steamed rice is handled, the evaporation of moisture draws away heat as heat of vaporization, which lowers the surrounding temperature. This matters because the temperature rises as koji mold multiplies, so adjustments are needed to keep the koji at its proper temperature. Heat of vaporization helps control the temperature of the koji and steamed rice, encouraging the fermentation process to proceed appropriately.