Kojimai
麹米
Brewing Process
Définition
The portion of steamed rice used for koji cultivation, comprising roughly 20-25% of total rice in a brew. Kojimai becomes the enzyme source that converts starch to fermentable sugar throughout the moromi fermentation.
En profondeur
Kojimai preparation demands the highest standards of rice steaming — the grains must be firm enough to allow koji hyphae to penetrate gradually (tsuki-haze pattern) rather than colonizing only the surface (nuri-haze). The kojimai ratio affects the overall enzyme balance: more kojimai means more saccharification power and potentially more amino acid production. Some breweries use a higher kojimai percentage for junmai styles to enhance umami, while reducing it for daiginjo to keep the profile clean.