[Tell me what you can't ask now!? Series 11] Don't be greedy for germs! ~A sake brewery where germs are not allowed to enter~
As October arrives, sake brewing has begun at many sake breweries. This time, for those who would like to visit sake breweries during the sake brewing season, we will talk about bacteria that are a nuisance when introduced into sake breweries.

In the autumn, when the rice plants, which are early-ripening, mid-ripening, and late-ripening varieties, are lowering their heads in succession and waiting to be harvested, preparations for the sake brewing season begin in the brewery, with meticulous cleaning of every nook and cranny, and thorough cleaning of tools.
In small sake breweries, where the sake brewing season often begins in the fall, this is referred to as "autumn washing," and is carried out as an important task to prevent the growth of bacteria that are not beneficial to sake brewing.
Koji mold, yeast, lactic acid bacteria... In sake brewing, which relies on the power of microorganisms that cannot be seen with the naked eye, it is considered taboo to introduce microorganisms (bacteria) that interfere with healthy fermentation.
This time, we will talk about sake breweries and bacteria. We will explain some of the most commonly heard nuisance bacteria and explain why they are so.
This person will explain

- Toji shop owner/producer Eri Nakano
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ProfileIn 1995, he opened the Japanese sake bar "Janapese Refined Sake Bar Tojiya" in Tenjinbashisuji, Osaka. He is active in various fields as a sake critic, seminar lecturer, and lyricist.
INDEX
● The situation is changing for natto bacteria
It is no exaggeration to say that natto bacteria are the epitome of what is detested. But that was a thing of the past. Things have changed a bit now.
One of the reasons why natto bacteria are not recommended is its high reproductive ability. Natto bacteria and koji mold have very similar environments suitable for growth. For example, let's say natto bacteria get into a koji room and attach to rice. The highly reproductive natto bacteria will surpass the koji mold, and the koji mold, deprived of its culture medium, will be unable to grow, and the rice will become known as suberi koji (also called sticky koji or slimy koji). The koji will be slimy and slippery to the touch, just like natto, and will no longer be usable for sake brewing.
Furthermore, once the natto bacteria had invaded the brewery, they demonstrated their toughness by surviving high temperatures and dryness, and even being defeated by disinfection with boiling water or cleaning with detergent, taking up residence in the brewery and causing trouble for a long period of time.
However, unlike the days when the strong wild natto bacteria were used, the pure cultured natto bacteria used in the manufacturing site, which is under strict hygiene control and has a clean environment, have become a little weaker and are no longer as harmful as they used to be. Also, the fact that well-polished rice has less protein, which is the favorite food of natto bacteria, also reduces their reproduction ability.
In addition, even though natto bacteria is a type of Bacillus subtilis that is normally found in soil and plants, the interiors of koji rooms, which were often made of clay walls mixed with rice straw, have now been changed to beautifully sawn wood, stainless steel, resin, and other materials, making it easier to maintain a hygienic environment, and so not all breweries are averse to natto bacteria. I know several sake brewers who eat natto even during the sake brewing season.
● I don't want you to eat it any more than natto!
So, what about the warning, "Natto is okay, but don't eat cheese, yogurt, kimchi, or pickles!"
These fermented foods contain lactic acid bacteria. While lactic acid bacteria act as a defense force against unwanted bacteria during the sake brewing process, there is a troublesome species of lactic acid bacteria called "hiochi bacteria" that can grow even when soaked in alcohol and have a negative effect on the quality of sake. However, in recent years, some reasons for optimism have been found. It has been pointed out that hiochi bacteria may have changed their nutritional intake slightly to survive as the rice polishing rate has increased since the 1990s and the vitamins and amino acids they feed on have decreased. Compared to sake yeast, which can be seen at a magnification of 300 times under an optical microscope, hiochi bacteria require a magnification of 1000 times to see, and can be examined using a hiochi bacteria detection liquid distributed by the Brewing Society of Japan.
All living things adapt to change and undergo transformation in order to survive. The strong become weaker and the weak become stronger... Please accept this reality and remember that it is good manners to avoid bringing in unnecessary bacteria.
Next time: [Tell me what you can't ask now!? Series 12]Moromi = Preparation = Making
Previous article: [Tell me what you can't ask now!? Series 10]About the yeast starter making process (mototate)

Toji shop
- Address
- 7-13 Kurosakicho, Kita-ku, OsakaOpen with Googlemap
- TEL
- 06-6371-0979
- Opening hours
- Monday and Wednesday 18:00-22:30 (L.O.), Tuesday, Thursday, Friday and Saturday 17:00-22:30 (L.O.)
- Closing days
- Sunday