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.