1. Soak and steam beans

After fully washing the soybeans, add 3 times the amount of water and soak them overnight, then pour out the water and steam them in a pressure cooker until the soybeans are pinched by hand. To the extent of crushing, about 45 minutes. If you don’t have a pressure cooker, don’t put too much water at once when boiling. In order to maintain the original flavor of soybeans, it is best to steam them.

2. Inoculate the natto bacteria

After dissolving the natto bacteria in 50ml hot water, add it evenly to the hot soybeans, stir quickly and distribute it into 7 foam lunch boxes Inside, the thickness is about 2cm, cover it with gauze or put a pair of chopsticks between the lunch box and the lunch box lid to make it fully exposed to the air. Because Nattobacterium natto is an aerobic bacterium, exposure to air is very important. But after fermentation, cover the lid and seal the mouth with tape to avoid contact with air for long-term storage.

3. Ferment at constant temperature for 14-36 hours

Put several rectangular plastic bottles filled with 50℃ hot water into a clean large foam box, and put the inoculated The bean mushroom foam lunch box is placed on the bottle, and the ideal temperature inside the box is 42°C. If the temperature inside the box drops to 38°C, replace the bottle with 50°C hot water again. After repeatedly changing the hot water in the bottle and fermenting for 14-36 hours, a white film will form on the surface of the soybeans, and when sticky threads appear, the soybeans will turn into natto.