The Koji Kitchen

I generally describe it as a sort of starter for different foods, similar to a sourdough starter or a kombucha SCOBY. The underlying biological processes are very different. Koji is a type of edible mold called aspergillus oryzae. There are other members of the aspergillus family that are also used in similar ways all over Asia. Koji is specifically Japanese and has been used there for well over 1500 years. Molds have been used in fermentation to provide complexity and depth in all sorts foods, from brie to salami. At the heart of it, like any fermentation, the microbes and enzymes break down some of the molecules in the starting ingredients into their constituent parts.