Mizukoji (water-koji mixing)

Mizukoji (水麹) is one of the important preparatory steps carried out before moshikomi (brewing mash preparation) in sake production. Specifically, a set amount of water is mixed with koji so that the saccharifying enzymes contained in the koji dissolve into the water in advance. The aim is to increase the speed and efficiency of the saccharification reaction once steamed rice is added later. It is usually carried out one to two hours before preparing the shubo (yeast starter) or the moromi (fermentation mash). Mizukoji is made when koji is mixed with water for the shubo, and also at the hatsuzoe (first addition), nakazoe (second addition), and tomezoe (final addition) of the moromi, with the water and koji needed for each stage mixed and prepared accordingly. This process helps fermentation proceed smoothly during brewing.