What is the primary purpose of Koji in Sake production?

The primary purpose of Koji in sake production is to convert starches into sugars. Koji is made from steamed rice that has been inoculated with a specific mold, Aspergillus oryzae. This mold produces enzymes, particularly amylase, which break down the starches present in the rice into fermentable sugars. These sugars are then utilized by yeast during fermentation to produce alcohol. This essential process of saccharification is crucial because sake is made from rice, which is high in starch content but lacks sugars that yeast can directly ferment.

While enhancing flavor, carbonating, and clarifying are important aspects of sake production, they are secondary processes to the critical conversion of starch to sugar that Koji oversees. Therefore, the action of Koji in generating fermentable sugars is foundational to the overall production of sake.