Koji (KOH-gee) Culture
Fermentation is an indispensable process in miso production. To activate the fermentation process, miso producers in Japan have always used a mold culture. The typical mold for fermentation is koji kin, also known as Aspergillus Oryzae.
Grains such as rice, barley or soybeans are inoculated with koji kin. The mold then propagates and results in the koji culture. Adding kome (rice) koji, the most commonly used culture, to other ingredients and fermenting them produces miso, soy sauce, sake and other fermented foods traditional to Japan, and growing in popularity around the world.
Koji culture has many uses. Not only is it necessary in fermentation, but when combined with other ingredients, it can be used for flavoring, curing and/or preserving foods. One such example of this is shio koji, a mixture of malted rice (koji), salt (shio) and water.