Humidity

Humidity is a measure of the amount of water vapor contained in the air, and is usually expressed as relative humidity. Relative humidity is the ratio between the actual amount of water vapor in the air at a given temperature and the maximum amount of water vapor the air can hold at that temperature, at which point it is saturated. Humidity is very important in the production and storage of sake, and if it is not kept at an appropriate level, it can affect the flavor and quality of the sake. In the fermentation and aging processes in particular, a moderate level of humidity is needed to optimize the activity of yeast and bacteria and to improve the quality of the sake. In storage environments as well, careful management is necessary: if humidity is too high it can lead to mold, while if it is too low the sake's volatile components are lost.