Recipe: Adzuki Bean Natto

Adzuki beans are known for their slightly sweet flavor, rich red color, high protein content, and relatively easy digestibility. They also make a mild natto. People who find soy natto too strong may enjoy this version.



  • Non-reactive pot (stainless steel, enamel, etc.)
  • Large stainless steel spoon
  • 3-4 oven-proof glass containers with lids


  • 2 lbs. adzuki beans (about 4 cups)
  • 2 tsp. water, boiled for 5-10 minutes to sterilize
  • One spoonful (0.1 g) Nattomoto Powder (use the special spoon that came with the Natto Spores)


  1. Wash beans and soak overnight, leaving space for beans to double in size.
  2. Drain beans from soaking water. Place beans in a large pot, fill with water and boil 1-2 hours. Check beans after 1 hour for tenderness. Beans should be just soft but not mushy.
  3. Drain the cooked beans and place in a sterilized pot.
  4. Dissolve one special spoonful of natto spores in 2 tsp. of sterilized water.
  5. Immediately pour natto spore solution over beans while beans are still warm. Stir the beans and water mixture together carefully using a sterilized spoon.
  6. Place a layer of beans no more than 3” thick in the oven-proof containers. If at any point during the process some beans are spilled, discard the spilled beans, as they can contaminate the other beans if added back in to the batch.
  7. Cover the containers with a lid or plastic wrap.
  8. Place the covered containers in the oven, dehydrator, or warmer and allow the natto to ferment for 22-24 hours being sure to keep the temperature between 98-110°F.
  9. At the conclusion of the fermentation period, let the natto cool to room temperature and store in the refrigerator at least overnight. The Natto can be consumed as early as the next morning and is often served as a Japanese-style breakfast. Natto can also be aged in the refrigerator for 3-4 days. It will remain fresh for eating for up to 2-3 months. The flavor will get stronger with a longer storage period.
  10. Smaller portions of finished natto can be stored in the freezer and thawed for later use.