noun
koji mold; Aspergillus oryzae
A mold used in Japanese fermentation to make koji, essential for sake, miso, and soy sauce.
日本酒はコウジカビの働きで米のでんぷんを糖に変える。
In sake, koji mold converts the starch in rice into sugar.
味噌を作るには、まず大豆にコウジカビを付けて麹
To make miso, first you inoculate soybeans with koji mold to make koji.
麹 (koji) refers to the fermented grain or soybean product itself, while コウジカビ specifically denotes the mold (Aspergillus oryzae) used to produce it.
Compound of 麹 (kōji, 'koji') + カビ (kabi, 'mold'). The reading こうじかび is a straightforward combination.