As you may know, sake is mainly produced with rice and water. Beside with them, there is one more quite important item. That is the yeast. The alcohol of sake is generated in the middle of process that yeast decomposes the glucose. In the same time, various kind of aroma components are generated.
Owing to this chemical reaction, some sake wearing fruits and flower are birthed in spite of using only rice and water as ingredients. In fact, most of aromatic sake is produced with using yeast produced lots of fruity and flamboyant aroma.

It is said that sake has around 2000 years history but it’s quite recent breweries started to use cultivated yeast. Until 1906, nobody had not known the existence of sake yeast, so that breweries had been brewing sake with taking the wild yeast in the sake barrel naturally. To know more about ancient methods, please refer this this article.

The cultivated yeast was rapidly spread all around Japan and dramatically improved the quality of sake. Up to date, various kind of yeast has been invented and contributes to improve and differentiate the taste.
Let’s deep dive into the micro world of yeast together! The June issue of SAKEMARU is of course “Yeast”. Please enjoy the sake produced with unique yeast.

●Yeast Distributed by Brewing Society of Japan｜協会酵母

National Research Institute of Brewing was shared moromi from a few breweries and researched and examined it to solve the mechanism of sake’s fermentation. Though this research, they found the existence of sake yeast in 1906. To advance further research, they asked lots of breweries to send moromi and found various sake yeasts.
Currently, around 30 kinds of yeast has been cultivated and distributed all around Japan. Their yeast is most commonly utilized for brewing. Followings are very popular yeast they cultivated.

「No.6」
The is the oldest yeast available now and divided from Aromasa shuzo in Akita and cultivated. Fermentation is very active and the aroma is gentle. Mild umami and sourness is the main characteristic of this yeast.

「No. 1801」
This yeast is invented in 2006 for high-grade sake like Daiginjo. It is current most competitive yeast, lots of breweries win the competition with Daiginjo produced with using this yeast. This yeast produced quite a lot of fruity aroma.

●Yeast Distributed by Local Brewing Society｜地方オリジナル酵母

In each region, there is also Regional Research Institute of Brewing. Yeast developed by them are normally closed in each region. This unique yeast help to stand each region’s characteristic.

「Research Institute of Brewing in Niigata」
This is only regional research institute dedicated to sake. This institute support 90 breweries, which is the largest number of brewery in Japan, to be more competitive.

「The Center of Industrial Technology in Yamagata」
Yamagata is called “Ginjo kingdam”. There a lots of delicious sake. This center sustain the basement of its high quality. In tightly linking up with Yamagata sake association, they define the original standard “DEWA33” sticking to the all Yamagata made ingredients. Please check the strict condition.

– Brewery : 100% Dewasansan 出羽燦々
– Polish rate : Less than 55%
– Grade : Junmaiginjo
– Yeast : Yamagata yeast
– Koji yeast : Olise Yamagata

●Self-Cultivated Yeast｜自家培養

Some very edgy breweries cultivate their own yeast in their small labo. It’s really science and takes very long time to divide only sake yeast and cultivate it to the practical level. However, it definitely becomes the ultimate weapon to differentiate own brand.

「Koshinohana shuzo’s story of self-cultivating yeast」
This brewery self-cultivate own yeast. With repeating try and error for a decade, they finally succeeded to produce the satisfactory yeast. One episode the owner told us with related to self-cultivating yeast was so interesting. One famous brewery had been opened to welcome visitors, however they quitted several years before.

The reason was like this. Other brewery’s spy was mixed in visitors and he stole an examiner of yeast and brought back to his brewery. After a few years, some people recognized the taste became very close to that brewery’s one and it was brought to light. I have learnt the importance of yeast in sake brewing.

●With Bubble, No Bubble｜泡なし/泡あり

It’s considered as the common sense that sake yeast generates bubbles along with its fermentation. Recently, it’s figured out that there are some sake yeasts are not along with bubbles. It’s very hard manual work to depress the bubbles, so that the machine is used recently.
With using no bubble yeast, brewing turns much more effective. 1) Manual work is not necessary, 2) Produce more sake in each barrel, since it’s not necessary to consider the amount of bubble.

Cultivation of yeast is just a newly born baby in the history of sake. However, it is also true that improvement of yeast brought the standard of sake to the next level.
It is very exciting to see how yeasts revolute the taste of sake in a next decade.