- Association Yeast No.9 (Kyōkai No.9)
Isolated around 1953 as Kumamoto Yeast (熊本酵母, Kumamoto Kobo) by Nojiro Kinichi at the Kumamoto Prefectural Brewing Research Centre. Distribution by the Brewing Society of Japan as Association Yeast No. 9 began in 1968, and it has been available ever since. Well-suited for ginjo brewing. Stains red in the TTC test, with a depression in the centre of large colonies, with deep, tight wrinkles.
In brewing, it is characterized by strong fermentation at low temperatures, and continuing strong fermentation even after ochi-awa, the stage at which the thick, deep taka-awa foam loses viscosity and disappears as it falls back. Number 9 foam is light in texture, and doesn’t rise very high. It is quick to reach the ji (地) stage (when the foam has fallen back and the surface of the mash becomes visible), so it tends to give “quick-starting, short” moromi. The finished sake tends to be low in acidity with prominent aromatics. Until the arrival of strains which produce ethyl caproate in large quantities, it was the most widely used variety for entries in the Japan Sake Awards (Zenkoku Shinshu Kanpyokai). Even today, it is widely used for making ginjo sake.