Koji
Japanese: 麹（こうじ）
A culture produced by growing koji mold (Aspergillus oryzae) on grains. A rich source of enzymes and the starting point of Japanese fermentation.
Koji is made by cultivating koji mold on steamed grains. The enzymes it produces convert starch into sugars and proteins into amino acids. Miso, soy sauce, sake, amazake — most Japanese fermented foods would not exist without koji.
Depending on the grain used, koji is called rice koji, barley koji, or bean koji. Each has a different enzyme balance, yielding distinct flavors. To enter the world of fermentation, start by understanding koji. It is indispensable to the Japanese table.