What does the term koji-kin refer to?

Koji-kin refers specifically to the mold used in sake production, primarily the Aspergillus oryzae variety. This mold plays a crucial role in the brewing process of sake because it is responsible for converting starches found in rice into fermentable sugars. During a process called koji making, koji-kin is inoculated onto steamed rice, where it grows and produces enzymes that allow for the starches to be broken down. This is a vital step that sets the stage for fermentation, allowing yeast to thrive and produce alcohol. Understanding the function and significance of koji-kin is essential for anyone studying advanced sake production, as it directly impacts the flavor profile and overall quality of the finished sake.