Recipe:Natto making manual short workshop form

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Nattō Making Manual

(for 500 g of soybeans, short workshop form)

- this version is temporary so far still testing

Active culture

  • dry nattō starter (Bacillus subtilis) - dilute dry starter in water preparing working solution - 1 g of dry powder per 10 ml, use 1 ml (1 teaspoon) of the working solution per batch, dissolve in 20 ml of 100°C water (has to be tested, but should work fine)
  • alternatively - use previous/other nattō bean ferment, dilute 3 soup spoons (+- 30 g) in 100 ml (1/2 of coffee cup) of 100°C water, strain to remove particles and use the liquid as a starter


  • soybeans (dried) - 500 g


  • 1x 3 l bowl for washing and soaking the beans
  • pressure cooker to boil or steam the beans
  • spoon or spatula for measuring and mixing
  • 1 l glass dose for culturing the beans
  • aluminium or plastic foil to cover dose with culture
  • something sharp to make holes in the foil like tooth pick
  • incubator at temperature over 38°C, preferably around 42°C

Working manual

- transfer 500 g of the beans into the bowl and rinse it few times with water disposing the wash

- after that add around 2-3 l of water to beans and let to soak for 8-12 hours, depending on temperature (warmer = shorter period of soaking)

- dispose the water and rinse twice or so

- move the beans to the pressure cooker and cook (boiling point) for 20 to 30 minutes till soft

- check the softness by pressing the bean, it should be easy to squeeze but not too mushy, it needs to be cooked completely

- strain the water from the beans and move them into a bowl

- add the nattō starter and mix well with the beans (# when preparing the liquid nattō starter, add 1 soup spoon of sugar (light brown) to a bowl, add the hot starter and mix till dissolved)

- move the beans into the glass vessel and cover by foil

- make holes in the foil more or less 2 cm from each other

- move the mix to the incubator set above 38°C, preferably around 42°C

- add a bowl/container with water to increase the humidity in the incubator

- within 24 hours the culture should be ready to harvest, letting it ferment for 48 hours is OK

- move the nattō ferment into the fridge and let it age at least for day or rather several days, it improves the flavour and texture

- once in the fridge remove the foil with the holes and replace it with lids which seals tight or another foil without holes to prevent drying of the ferment

- if the ferment gets too old - too much mature, you can still use it for cooking or starting a new batch (if not contaminated)