Spreading of the mash

Here Koji is mixed into the sweet potato mash bill. Koji is made from cooked rice and/or soya beans, which is cultured with Aspergillus oryzae. Koji forms a base of many traditional Japanese products such as Soy sauce, Miso and Mirin. The enzymes present in the culture are used to break down the complex starches into sugars that the yeast can act upon to ferment into alcohol and carbon dioxide.