Natto is a traditional fermented food that has evolved through the centuries. Today there are countless natto brands, flavors, and presentations in Japan, each with a distinctive taste due to the bacteria strain and soybean used.
Procedural factors, known as the “know-how” of each company, also affect the product’s flavor. In brief, the industrial natto manufacturing process is as follows.
The first step is soaking the soybeans in water. It looks simple, but it is delicate to carefully decide the immersion time according to daily situations such as the season and the weather.
The boiling needs to be adjusted while monitoring the soybeans.
3. Spray of natto bacteria
After steaming, we apply natto bacteria to the soybeans and stir evenly.
We divide the inoculated soybeans into small portions and place them in the fermentation room. We constantly monitor the natto and evaluate the fermentation progress. This part requires the expertise of the natto master for achieving the brand’s distinctive flavor and aroma.
Natto manufacturing process
- Soybeans are soaked in water overnight.
- Steam and soften the soybeans.
- Spray natto bacteria on the steamed soybeans and mix.
- Fill small containers with the steamed soybean and ferment at 40-42℃ overnight in the fermentation room.
- Finishing / packing / shipping.
The water used for soaking, temperature, soaking time, boiling time, shape and material of the container, temperature, and humidity of the fermentation room, fermentation time, Etc., are essential factors for developing the desired natto flavor aroma and nutrients. Other factors to consider are the outside air temperature and humidity.
For outsiders, producing natto in a factory looks like a mechanical and repetitive process. Still, the truth is that it is not possible to maintain the same taste and aroma without controlling a multitude of variables.
Natto making is a feat of technology, tradition, and craftsmanship.
By the way, there is one factor that goes beyond human control, the function of Bacillus natto in the fermentation process.
Microorganisms such as Bacillus natto reproduce by copying their own genes and dividing. The billions of natto bacteria in one pack of natto have the same gene; in other words, they are the same organisms. Their work should be the same, but in reality, there is a difference.
Natto bacteria (B. subtilis) have lived in this world for tens of thousands of years.
As humans, we are just beginning to unveil their secrets.
Sonomono Inc. Academic Advisor
Mr. Ogasawara graduated from Kumamoto University Graduate School of Medical Education. He actively researches and develops functional raw materials such as nattokinase. His professional experience as a researcher over more than 35 years includes microbiology, fermentation, enzymology, and bacterium.