What is the role of amylase in sake fermentation?

Amylase plays a critical role in the fermentation process of sake by breaking down starches present in the rice into sugars. During sake production, the rice is polished to remove the bran and then steamed to make it gelatinous. The addition of koji mold (Aspergillus oryzae) to the steamed rice initiates a process called saccharification, where enzymes produced by the koji, including amylase, convert the complex carbohydrates (starch) into simpler sugars that yeast can then ferment into alcohol.

Understanding this function is vital as it highlights the importance of both koji and its enzymes in the transformation of raw materials into final sake. Without the action of amylase, there would be insufficient fermentable sugars available for the yeast during fermentation, which would significantly hinder the production of alcohol and the overall quality of the sake. This is why the answer regarding the role of amylase in converting starch to sugar is the correct one.

In contrast, while acids can play a role in flavor and stability, they are not produced directly by amylase. Similarly, while enhancing aroma is important in sake, it is mainly due to different fermentation products, not amylase. Lastly, stabilizing the fermentation environment involves other factors