Hi-ire (Pasteurization)
Japanese: 火入れ（ひいれ）
Heating to stop fermentation and stabilize quality. Also halts enzyme activity.
Hi-ire heats miso or soy sauce to about 60-80°C, stopping microbial activity and enzyme reactions. This halts flavor change and improves storage stability.
Pasteurized miso is easier to distribute and store, but loses its 'living' characteristics as enzymes are inactivated. The choice between pasteurized and raw is a trade-off between convenience and flavor. Sake hi-ire follows the same principle — practiced in Japan centuries before Pasteur. Temperature and duration are balanced to preserve flavor while ensuring stability. Too high destroys flavor; too low leaves pasteurization incomplete.