1. Use of utensils and materials

①500g of soybeans ②0.3g of natto bacteria or half a box of natto (25g) ③Pressure cooker ④Stainless steel basin ⑤Foam rice

Shallow containers such as boxes ⑥ Foam box ⑦ 2-liter rectangular plastic bottle or hot water bottle ⑧ Thermometer 2. Steamed soybeans

After the soybeans are fully washed, add 3 times the amount of water to soak overnight, and then pour them away Pour water into a pressure cooker and steam until the beans can be crushed with your hands, about 45 minutes. It's okay to cook if you don't have a pressure cooker, but don't put too much water at one time

when cooking. In order to maintain the original flavor of soybeans, it is best to steam them.

2. Inoculation of Natto bacteria

Natto bacteria can multiply about 2 times in 30 minutes at a suitable temperature. Therefore, for 500g of dry soybeans, the amount of natto

bacteria used is only 0.3g. Dissolve it in 50ml hot water, add it evenly to the hot soybeans, stir evenly quickly

and divide it into 7 foam lunch boxes with a thickness of about 2cm. Cover it with gauze or put it between the lunch box and the rice

Place a pair of chopsticks between the lids so that they are fully exposed to the air. Because Natto bacteria are aerophilic bacteria, exposure to air is very

important. But after fermentation, the lid should be closed and the mouth should be sealed with tape.

If you use natto, choose the brand of soybeans you like to eat, freeze it, and use it as

strain. The usage amount of 500g dry soybean natto bacteria is half a box (one box is 50g). Add it to the hot beans as above.

3. Ferment at constant temperature for 14-15 hours

Put several rectangular plastic bottles filled with 50℃ hot water into a clean large foam box, and place the inoculated

Natto foam lunch box is placed on the bottle. The ideal temperature inside the box is 42°C. If the temperature inside the box drops to 37°C,

replace the bottle with 50°C hot water. After repeatedly changing the hot water in the bottle and fermenting for 14-15 hours, a white film will appear on the surface of the soybeans. When sticky threads appear, the soybeans will turn into natto. Cover tightly and store in the refrigerator at low temperature

.

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 keep it safe. Constant temperature inside. Pay attention to more exposure to air.

4. Post-ripening

Ferment at a constant temperature of 40℃-42℃ for 14-15 hours, then place it in the refrigerator for low-temperature maturation for several hours

, the finished natto will be better both in appearance and taste. Therefore, it is recommended that after the natto is cooked, it should be placed in the refrigerator to mature at low temperature for a few hours before eating.

5. Preservation of Natto bacteria

Powdered Natto bacteria are particularly stable in the spore state and can be stored for a long time as long as they are placed in a cool and dry place.

But after opening, it must be stored in the refrigerator at low temperature. 7. Production key

① Pay attention to maintaining a constant temperature of 40℃-42℃.

②Natto bacteria should be inoculated into hot soybeans.