Equipment · Incubators and warm holds
Natto incubation chamber
A warm, humid enclosure for natto, the Japanese fermented soybean dish made with Bacillus subtilis, holding it at roughly 35 to 45 C for about a day before cooling.
What it is
A natto incubation chamber is a warm, humid enclosure that holds vented containers of steamed soybeans inoculated with a commercial natto culture. The chamber must limit drying without blocking gas exchange, and the beans need a temperature reading at the bean mass rather than only at the air.
Natto is an alkaline fermentation driven by Bacillus subtilis, not an acid one. The acidification rules of tempeh or pickled vegetables do not apply to it.
Sources for this section
Temperature and time
The sources give different points. A 2021 study of natto made with one Bacillus strain reported its best conditions at about 35.5 C for 24 hours, followed by 24 hours at 4 C. A traditional method placed steamed beans in straw and incubated them at about 40 C for around 24 hours. A patent describes a natto fermentation zone of 40 to 53 C.
A 16-hour fermentation at 40 C was not found in the consulted sources and should not be used without a source.
Sources for this section
Equipment details
Limits
Whether the controller and humidity sensor are rated for the warmer humid regime is unverified.
SourceNatto is an alkaline fermentation; acidification rules from tempeh or vegetables do not transfer.
Source →Places
Documented for international use, with no single place of origin assigned.
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Sources
PubMed Central (Foods)Method · Science
Effect of Fermentation Parameters on Natto and Its Thrombolytic PropertyBest natto conditions reported at about 35.5 C for 24 h, with 4 C ripening afterwards.
Cited in: What it is; Temperature and time
UBC FNH200 course wikiHistory · Method
NattoTraditional method: steamed soybeans in straw, incubated around 40 C for about 24 h.
Cited in: Temperature and time