What is koji-kin?

Koji-kin refers to the mold Aspergillus oryzae, which plays a crucial role in the production of sake. This mold is responsible for the saccharification process, where it breaks down the starches present in rice into fermentable sugars. This conversion is a vital step in sake brewing, as the sugars produced will then be fermented by yeast to create alcohol. Without koji-kin, the starches in the rice would remain unconverted, and fermentation would not occur effectively, ultimately impacting the quality and characteristics of the sake.

The other options do not accurately describe koji-kin; rice used for sake is referred to by specific varieties rather than as koji-kin, yeast variants are separate microorganisms from the mold, and fermentation enhancers may refer to a range of additives that are not tied directly to the essential role of koji-kin in the brewing process.