The Practice of Fermentation in Japan

What are common Japanese Fermented foods?

Fermentation is a process that has been historically used in many different cultures. Traditional Japanese cuisine contains varieties of food items and ingredients that are fermented. For example, soy sauce (shoyu), miso, and natto are fermented from soybeans. There are more than 1,500 producers of soy sauce and at least 1,000 makers of miso in Japan. Sake is also traditional fermented alcohol. Sake is made essentially from water and rice, with the help of yeast, koji, and lactic acid bacteria. And Koso-drink is becoming popular among young women for several years. Koso is one of the fermented drink which has around 100 years of history. It is made with many different vegetables, fruits, plants. This drink represents health and wellness from the old days. R’s KOSO is one of the Koso-drink which is made with over 100 different vegetables, fruits, plants, a special combination of yeasts and essential bacteria.
These are essential ingredients in dietary habits of Japan. It is impossible to separate Japanese food culture from fermentation. Japan has a long history of making and using fermented products. Traditional method of fermentation has been succeeded and also improved with the development of science. That is, it is said that Japanese technology of fermentation and the quality of fermented products are one the best in the world.
The major factor why Japanese and Asian fermentation cultures have become richer is the influence of climate. When the humidity is high, fermentation tends to proceed and mold tends to stick. As a result, people naturally and purposefully faced fermentation and developed a fermentation culture.

What Happens during the Process of Fermentation?

Fermented foods are vastly different from their unfermented counterparts. They have therapeutic benefits that are not found in unfermented foods. At this moment you may be wondering, “well how is that possible?”. In order to understand why, we must first understand the process of fermentation.
Fermentation refers to the process by which microorganisms break down carbohydrates in the food under anaerobic (oxygen-free) conditions. The lactic acid bacteria, known as the Lacobacillus species of bacteria, plays an important role in the fermentation process. Lactic acid bacteria release lactic acid, which in turn creates the ideal condition for the growth of beneficial microorganisms known as probiotics. These probiotics form a community which break down carbohydrates such as sugars, starch and indigestible fibre. Thus, the sugar content is decreased, and the foods are rendered more digestible. 
At the same time, the breakdown of indigestible fibre matrix leads to the release of nutrients. Thus, the bioavailability of nutrients in the food is increased through fermentation. Furthermore, in this process transform nutrients and release “bacterial by-products” which have been shown to beneficial for human health. These “bacterial by-products” include nutrients such as vitamin K, B vitamins. They also include short-chain fatty acids which nourish our body and modulate our immune system. Fermented foods differ greatly from their starting ingredient, as they embody a different nutrient profile, texture, appearance. They are known to be easier to digest, have high nutrition value, and possess immense therapeutic value.

The Practice of Fermentation - R's KOSO -


Therapeutic Benefits of Probiotics in Fermented Foods

Traditional fermented Japanese foods have been shown to protect against pathogenic (harmful) microorganisms, help with digestion, facilitate bone formation, as well as promote a healthy immune and cardiovascular system. The Lactic acid bacteria, which is found in most fermented foods, have been shown to modulate our body’s immune system and its immune response. In fact, the strain L137 has been approved and commercialized as a probiotic to prevent against pollen-induced allergic reactions, and further research is being done to test the use of lactic acid bacteria in allergy desensitization and prevention. Traditional rice vinegar, which contains probiotic yeasts such as Saccharomyces cerevisae and lactic acid bacteria, has been found to exhibit antioxidant properties and anti-tumor activity in mouse models. Furthermore, soy sauce promotes gastric juice production and exhibits antioxidant capacity, while natto contains antibacterial molecules, high levels of vitamin K which stimulates bone formation, as well as nattokinase which has been shown to break down fibrin clots associated with heart disease. Furthermore, increasingly research studies show that the probiotics found in fermented food can modulate weight and improve mood and brain health.


Fermentation has been an integral aspect of Japanese culture and cuisine. In many fermentation facilities, the practice of fermentation has been developed and refined to enhance the aroma, texture, taste, overall quality, and passed on for generations. Fermented whole foods are not only a source of healthy proteins, fats, carbohydrates, vitamins, minerals, and phytonutrients which are active biochemical components that might help prevent us from getting disease and keep our body function properly, but also a source of health-enhancing nutrients, probiotics, prebiotics, and enzymes. Fermentation is a process which holds immense therapeutic potential.

Traditional Healthful Fermented Products of Japan (publication)

発酵食品学 小泉武夫 講談社 

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