Healthy, homemade nattō made using an instant pot .
Cover the beans with the sterilized cheesecloth (or dish towel) and then put on the glass lid. This will keep the beans moist, but prevent condensation from dropping on the beans.
Set the Instant Pot to the yogurt "YOGT" setting for 20 to 24 hours. The temperature should remain between 90 and 104 F (30 - 40 C). Even though the Instant Pot does a good job of maintaining the temperature, I like to keep the thermometer in the pot and check it every so often.
Once the cycle is finished, you can check the beans to see if fermentation is complete. Using a clean, sterilized spoon, gently stir a small area of beans. If stringy strands form easily, the beans are ready.
Let the beans cool for a few hours, then place the beans in the refrigerator to “age” for one to three days. This will slow down fermentation and enhance the flavor. Since the IP takes up so much space, I prefer to transfer the natto in a separate container (or two).
We usually put the nattō in two separate containers before aging so that once complete, we can keep one in the fridge to eat within the week and then store the other in the freezer for later.
Also, if you notice your nattō is not very sticky, you may need to get a fresh batch of spores. Good luck and enjoy!