Koji

Koji the Japanese name for a product which consists of steamed cereal (usually rice) or legumes, fermented for several days, to provide a starter for preparing other fermented products, including soy sauce, miso, and saké. A flat yellowish-green cake in appearance, it is not edible itself but is rich in the enzymes needed for making these edible end products. The mould Aspergillus oryzae is the most prominent of the fermenting agents which produce koji, but many others may be involved, depending on the precise results to be achieved.