Using utensils and materials

① 500g soybeans

② 5g natto bacteria

③ Pressure cooker

④ Stainless steel basin

⑤ Foam lunch box and other shallow containers

⑥ Foam box

⑦ 2 liter rectangular plastic bottle or hot water bottle

⑧ Thermometer

Soaked beans and steamed beans

After fully washing the soybeans, add 3 times the amount of water and soak them overnight, then drain the water and put them in a pressure cooker to steam 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 add too much water at once when boiling. In order to maintain the original flavor of soybeans, it is best to steam them.

Inoculate Natto bacteria

After dissolving the Natto bacteria in 50ml hot water (the best temperature is 38-45°C, too high a temperature will kill the Natto bacteria), evenly Add to the hot soybeans, mix quickly and evenly, and distribute into 7 foam lunch boxes with a thickness of about 2cm. Cover the top with gauze or place a pair of chopsticks between the lunch box and the lunch box lid to make it fully exposed to the air. Because Natto bacteria are aerophilic bacteria, 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.

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 inoculate the Natto bacteria The 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. If there is no foam box, you can also use a large cardboard box, wrap it with quilts and electric mattresses, or insert a 45°C light bulb into the box to maintain a constant temperature in the box. Pay attention to more exposure to air.

Post-ripening (low-temperature dormancy of live bacteria)

Ferment for 14-36 hours at a constant temperature of 38-42°C, and then placed in the refrigerator for low-temperature maturation for several hours. Natto will look and taste better. Therefore, it is recommended that after the natto is prepared, it should be placed in the refrigerator to mature at low temperature for several hours before consumption or long-term storage.

Production Keys

① Pay attention to maintaining a constant temperature of 38-42℃.

② Natto bacteria should be inoculated into hot soybeans (the best temperature is 38-45°C, too high a temperature will kill the Natto bacteria).