Tane-koji
種麹
Definition
Koji starter spores, the powdered Aspergillus oryzae preparation that brewers sprinkle over steamed rice to begin koji cultivation. Tane-koji is produced by a handful of specialized suppliers (moyashi-ya) who have maintained spore cultures for generations.
In Depth
Only about ten moyashi-ya remain in Japan, each guarding proprietary strains of A. oryzae with specific enzyme profiles suited to different brewing goals. The tane-koji is applied to cooled steamed rice in the koji-muro, typically by hand from a fine-mesh canister shaken over the rice bed. The amount used is tiny — roughly 100 grams per ton of rice — but the choice of tane-koji strain profoundly influences the resulting sake. Strains producing more amylase create sweeter koji; those with higher protease yield more umami. This invisible ingredient is one of sake's most consequential decisions.