A koji starter, simply referred to as "koji," is a crucial ingredient in the traditional Japanese fermentation process. Koji is a type of fungus, specifically the Aspergillus oryzae, that is used to inoculate and ferment various food products. It plays a fundamental role in the production of several Japanese staples, including soy sauce, miso, sake, and mirin.
Additionally, koji is available commercially as a starter culture, making it more accessible for home cooks and producers who want to experiment with fermentation and traditional food preparation.
The specialty of this koji starter in amazake* production lies in its ability to convert starches into sugars, primarily through the action of the enzyme amylase.
* A traditional Japanese sweet, non-alcoholic beverage. Amazake is made from fermented rice and is known for its sweet taste and smooth, creamy texture.