Aspergillus oryzae, also known as kōji mold , is a filamentous fungus used in Japan to saccharify rice, sweet potato, and barley in the making of alcoholic beverages such as sake and shōchū, and also to ferment soybeans for making soy sauce and miso. However, in the production of fermented foods of soybeans such as soy sauce and miso, Aspergillus sojae is mainly used instead of A. oryzae. A. oryzae is also used for the production of rice vinegars. Barley kōji (麦麹) or rice koji (米麹) are made by fermenting the grains with A. oryzae hyphae.
