Koji extract (koji-ekisu)

Koji extract is a liquid obtained by adding water to rice koji, saccharifying it at around 55°C, and then filtering it. The liquid is rich in sugars and amino acids produced by the koji mold, and it is used mainly as a culture medium for growing yeast. Koji extract plays an important role in sake brewing and in food culture, and, taking advantage of the properties of koji, it is also sometimes used in the production of various fermented foods. It is also sometimes called koji juice (koji-jiru).