What is the role of Kōji mould in sake production?

The role of Kōji mould in sake production is primarily to produce enzymes. Kōji mould, specifically Aspergillus oryzae, is crucial in the initial stages of sake brewing, as it breaks down the starches present in the rice into fermentable sugars through enzymatic activity. This process is essential because yeast can only ferment sugars, not starch, so the action of Kōji is fundamental for a successful fermentation.

During the sake brewing process, Kōji is cultivated on steamed rice, and it works to convert the complex carbohydrates into simpler sugars that the yeast will later consume. This enzymatic transformation is vital for developing the alcohol and the complexity of flavors in the final product.

Other options do not accurately reflect the function Kōji plays; for instance, Kōji does not prevent fermentation or enhance acidity, nor is it involved in aging the rice itself. Its primary contribution lies in its enzymatic production, making it a cornerstone of the sake brewing process.