What role does koji play in Shochu production?

Koji plays a crucial role in Shochu production as a mold fermentation agent. This specifically refers to the use of the Aspergillus oryzae mold, which is vital for saccharification, the process of converting starches into sugars. In the production of shochu, koji is mixed with the raw materials (which can include barley, sweet potatoes, rice, or buckwheat) to initiate fermentation.

During this fermentation process, the enzymes produced by koji break down complex carbohydrates into simpler sugars, which can then be fermented by yeast into alcohol. This step is essential because, without the koji mold, the raw ingredients would not be effectively converted into fermentable sugars, resulting in a significantly lower alcohol yield and affecting the final flavor profile of the shochu. This means koji is integral not just for fermentation but also indirectly contributes to the overall character and taste of the spirit, differentiating it from other types of distilled drinks.