Sweet acid base

If you were watching the recent Taste With the Toji session featuring the Kotobuki Brewery in Osaka, you may have caught French brewer Guillaume Ozanne talking about a rare sake starter, sanki amazake moto (酸基醴酛), that they’re using.

This was a new one on me, and initially it was a bit challenging to figure out what exactly this starter was. The first hits I got were from the ever-useful SAKETIMES and a blog charmingly titled Kuu-neru tokoro (食う寝るところ, place to eat and sleep), both talking about Hirota Shuzōten (now Shiwa Shuzōten) in Iwate Prefecture. The brewery is in the town of Shiwa, stronghold of the Nanbu Tōji, and their tōji Hiromi Ono is the first female member of the guild. 

Shiwa Shuzōten describe sanki amazake moto as a type of kimoto, which makes sense as lactic acid is not added directly but is instead produced by bacteria. An amazake-like base is prepared using steamed rice, kōji and hot brewing water, then lactic acid bacteria are added. The brewery site says that the bacteria are chosen for the type of sake being brewed, and the Kuu-neru tokoro blog adds that these are kura-tsuki nyūsankin (蔵付き乳酸菌, lactic acid bacteria naturally present in the brewery) cultured by the Iwate Industrial Research Institute. 

The academic paper “Sake brewing using sanki amazake moto” published in the Journal of the Brewing Society of Japan in 2021 gives some background on how the starter was developed. Sake brewing was still fraught with failure during the Meiji Period, through spoilage of in-progress fermenting batches (fuzō, 腐造), contamination with hi-ochi bacteria or due to fires at breweries. Sake was an important source of tax revenue at that time so researchers were actively looking for new brewing techniques that would stabilise the process. [No mention of whether it affected fires…] 

One of these researchers was Kenjirō Eda, who published a work entitled Latest techniques for continuous sake brewing: Domestication of lactic acid bacteria (my translation, 最新清酒連醸法：乳酸馴養) in 1912 or 1913, and some of the techniques described in the book are still in use. Eda also experimented with a tanjun amazake moto (単純醴酛, simple amazake starter) where cultured yeast was added to the amazake base, but it did not produce enough alcohol, had off-aromas and lacked balance. Eda then developed the sanki amazake moto while trying to improve this simple starter method.

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Kotobuki Brewing site (Japanese)
酸基醴酛（さんきあまざけもと）を味わう (MSLAB Kuneru 12 Feb 2021 Japanese)
すべての酒を「酸基醴酛(さんきあまざけもと)」で醸す ─ 米の旨みを実感できる酒造りに挑む岩手の小さな酒蔵・廣田酒造店を紹介 (SAKETIMES 16 Jan 2019 Japanese)
酸基醴(あまざけ)もとを用いた清酒製造 (Journal of the Brewing Society of Japan, vol. 116 issue 11 p. 736-747, Nov 2021 Japanese)
最新清酒連醸法 : 酸類馴養 (Kenjirō Eda, scanned copy available from the Japanese National Diet Library, Japanese)