How to make natto (fermented soy beans)

Updated March 18, 2017

Natto, a Japanese dish of fermented soybeans, is best summed up as an acquired taste. Some people will be put off by strong smell, unusual taste and sticky web between each bean, but others just can't get enough. This healthy protein-packed food has been around for thousands of years in Japan, often enjoyed for breakfast. Once you've made natto you can eat it on a bed of rice, mixing in mustard or soy sauce if you desire.

Wash 5 cups of dry soybeans and put them into a glass bowl.

Submerge the beans in water and stir with your hands for 20 seconds; this will remove any dead skin or dirt on the beans.

Pour the water out of the bowl and then fill it up again with fresh water. Again, make sure the beans are covered.

Stir the mixture with your hands for 20 seconds and then remove the water once more.

Rinse the soybeans thoroughly with water.

Put the bean into a large bowl and add water. The bowl should contain a quarter beans and three-quarters water. Leave the beans to stand for the night.

Add the beans to a stainless steel colander and put it in the pressure cooker. Fill the pressure cooker with 1 cup of water.

Place the lid onto the pressure cooker and put the whole thing onto the stove. Cook on high heat; lower when cooker starts to hiss.

Turn off the stove after 45 minutes and allow the pressure cooker to cool down. The soybeans should be nice and soft.

Place the pressure cooker in a sink full of cold water if you want to quicken the cooling time.

Quickly mix 5 cups of natto-kin with the beans with a wooden spatula. Recover the pressure cooker once done but remove the air hole cover.

Put the cooker in a picnic ice-chest and cover it with an electric heating pad. Turn the heating pad on and allow the natto to ferment for two days.

Move the natto to the refrigerator and allow it to age for three days, though it is also fine to eat after only a few hours.

Things You'll Need

  • 5 cups of dry soybeans
  • Water
  • Large bowl
  • Pressure cooker
  • Natto-kin
  • Wooden spoon
  • Cup
  • Picnic ice-chest
  • Electric heating pad
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About the Author

Based in the U.K., Martin Cole has been writing since 2009. His articles have been published in "The Evening Chronicle," "The Journal" and "The Sunday Sun." He holds a Bachelor of Arts in journalism from Northumbria University.