Multiple parallel fermentation (並行複発酵)
Multiple parallel fermentation ("並行複発酵") is a type of fermentation that takes place in the sake brewing process, meaning that saccharification (the conversion of starch into glucose by koji enzyme) and fermentation (the conversion of glucose into alcohol by yeast) occur simultaneously in the same container. It can also be written as "並行複醱酵" or "並行複醗酵" in Japanese.
High-alcohol sake with almost 20 percent alcohol content can be produced only in the multiple parallel fermentation process. This is because glucose produced as a result of saccharification can be promptly consumed in the alcoholic fermentation process. If adopting the process of alcoholic fermentation after saccharification used for foreign liquors, the concentration of glucose has to be high to produce alcohol with 20 percent alcohol content, which will turn into weak starch syrup and stop the yeast activity.
Additionally, koji mold (aspergillus oryzae) is aerobic and cannot reproduce itself in the container with moromi (raw unrefined sake). The enzymes produced by koji are used in the saccharification. On the other hand, yeast fungus (saccharomycete) can reproduce itself in moromi. Thus, when adding raw materials such as steamed rice and water to moromi, koji needs to be added at the same time.
The alcohol beverages produced in the multiple parallel fermentation process are specific to the East Asian countries, known as Huangiju (yellow wine) such as Shaoxing rice wine from China, Makgeolli from Korea, and Japanese sake.
In the brewing process to produce beer and whiskey, saccharification does not occur simultaneously with alcoholic fermentation, but separately from, so it is called tanko fukuhakko (fermentation after saccharification).
Also, the process to produce wine from raw materials, in which glucose is already included, is called tan hakko (single fermentation) since it does not require saccharification but alcoholic fermentation.