- Association yeast
The production and distribution of pure sake yeast seishu kobo began in the year the Brewing Society of Japan (Nihon Jozo Kyokai, last three “o”s long) was founded, in 1906. In 1904, the Brewing Research Institute had been established and developed the sokujo method of making yeast starter, making the distribution of pure yeast cultures a necessity. The original method of distribution saw yeast bottled in the quantity necessary for addition to shubo.
Until 1916, the bottled yeast was simply offered as “First-class Sake Yeast” (甲種清酒酵母) . After 1917, however, various different strains were distributed under numbers from One to Six. The origins and date of isolation of the first five strains are as follows.
No. 1: isolated in 1906 by Takahashi from shubo at Sakuramasamune (Hyogo Prefecture).
No. 2: isolated from shinshu made at Gekkeikan (Kyoto Prefecture) in the late Meiji Period (1868-1912).
No. 3: isolated from shinshu made at Suishin (Hiroshima Prefecture) in 1914.
No. 4: isolated from an unidentified Hiroshima brewery in 1924.
No. 5: isolated from shubo and shinshu from Kamotsuru (Hiroshima Prefecture) around 1923.
In 1940, only Number 6 was available, but after that new yeasts were distributed. Currently, the foaming yeasts available are Nos. 6, 7, 9, 10, 11 and 14. Non-foaming yeast (awa-nashi-kobo) varieties are 601, 701, 901, 1001, 1401 and 1501. Such yeasts have been distributed in glass ampoules since 1967. Dried-yeast versions of 701 and 901 are available for kobo-jikomi. Other Association Yeasts are supplied only to producers who have entered into specific contracts with the Association. These include: “red” yeast (gives a red colour to the sake); non-urea producing yeast（KArg, Nos. 7, 9, 10, 701, 901 and 1001）; and High-aroma-component-productive yeast (1701, 1801, 1901 and so on).