Naka koji (koji added in the second stage of mashing)

Naka koji (仲麹) is the koji used in the naka stage of sake brewing, the second addition of the three-stage mashing process (sandan jikomi). Sake is generally made in three stages, and a different batch of koji is used at each one. The koji used in the first stage is called soe koji (添麹), the koji used in the second stage (naka jikomi) is naka koji, and the koji used in the final stage (tome jikomi) is tome koji (留麹). Naka koji plays an important role in promoting fermentation and adds depth to the flavor and aroma of the sake.