How Fermented Beans Are Used in Japan?

By Umami Recipe
How Fermented Beans Are Used in Japan?

Thanks to recent health trends, fermented foods have gained in popularity and are now largely accepted in many parts of the world. Fermentation is a metabolic process of converting carbohydrates to alcohol or organic acids using microorganisms under certain conditions. Different combinations of microorganisms and foods create different tastes and flavors.

Fermentation has a great history as a food preservation method found in various cultures all over the world. You may be unknowingly consuming fermented foods everyday---wine, beer, bread, yogurt and even coffee. So how is Japanese fermented foods different from those listed? The key is in the process by which the complex combinations of microorganisms interact to produce the desired result. Fermented beans, especially soybeans, are an indispensable ingredient in Japanese health cuisine.

Let's take a dive into the details of Japan's unique ferment foods.


While sushi has become a common sight worldwide, shoyu--Japanese soy sauce--can be found in nearly any grocery store in the US and in other countries. Despite its high sodium content, shoyu can be a substitute for salt. The savory taste and fragrance of shoyu helps to limit sodium intake when compared to salt.

Shoyu, an all-purpose cooking and table sauce, is made from a mixture of steamed soybeans, wheat, water and salt that has been fermented using koji (the active fermenting microorganism). Koji on the soybeans and wheat generates chemical reactions that produce the bold color, intense flavor and umami of shoyu. After the fermentation, it's pressed to separate the solids from the liquid shoyu. The raw shoyu is heated to eliminate any active microorganisms remaining and filtered to remove any fine particulates before bottling.


Miso--fermented soybeans paste--is a traditional Japanese seasoning. This salty paste is a great source of protein, and rich in vitamins and minerals. Miso is used for spread, dipping sauce, pickling vegetables, meat and fish, and making miso soup. You may have guessed, the most popular dish using miso is miso soup (misoshiru) which is served with white rice. Once you mix miso into dashi-stock and add vegetables, tofu or seaweed, miso soup can be a completely balanced and nutritious dish.

Basic miso is made from soybeans, salt and koji. Sometimes rice or barley is used as an ingredient to add regional uniqueness. Traditionally, miso would be made at home, each household having their own recipe, but recently this practice has become uncommon in Japan. However, there is seems to be a trend outside of Japan to make home-made miso. You just need simple ingredients and some patience for the fermentation process.


Natto, fermented soybeans, is said to be one of the most challenging Japanese dishes for foreigners to eat and actually enjoy. The pungent smell, sticky and slimy texture and nutty flavor is too extreme for even some Japanese people. But if you can get over these roadblocks, natto has great nutritional value. It contains as much protein as the same amount of beef with fewer calories, and also is a great source of Vitamin K2, which is hard to find in other foods. What’s more, natto contains, vitamin E, B2, C, iron, zinc, selenium and copper which play an important role in immune function and prevention of blood clots.

To prepare natto for eating, place a pack of natto into a bowl, add shoyu or seasoning and karashi (Japanese mustard), and mix thoroughly with chopsticks. Traditionally served with a bowl of steamed rice, natto can also be paired with sushi and other dishes.


Tsukemono, Japanese pickles, is another traditional dish which goes well with steamed rice. Although there are many kinds of tsukemono, a typical fermented pickle is nukazuke (pickled in rice bran). Thanks to the fermentation process, fresh vegetables turn into pickles after being buried in a pickling bed (nukadoko) for days or months. Nuka is a rice bran which peels off from brown rice in the process of being polished into white rice. The bacteria that naturally live on your hands and the surface of vegetables turn vitamin-rich nuka powder into nukadoko, which is the live culture of microorganisms. Once you start to mix your own nukadoko, it needs to be stirred by hand at least once a day to aerate and grow.


Dashi stock has a significant role in Japanese cuisine, and katsuobushi--fermented dried fish fillets--is its fundamental ingredient. It gives a smoky and savory flavor and delicate aroma, and is also a great source of umami. This umami ingredient enhances miso soup to have even greater flavor.

Katsuobushi uses mold, much like in the fermentation technique used for salami. To make katsuobushi, steam bonito meat, dry it, repeatedly mold it and sun-dry. The finished product is as hard as a rock due to the low moisture content, so it needs to be shaved to a paper-thin state before use. Soak these strips in water to make dashi stock, or sprinkle it dry as the final topping on a dish.


When people talk about Japanese sake, they usually means seishu. Seishu is clear sake, which is brewed alcoholcontaining 15-22% alcohol. To make seishu, rice, koji and water go through three steps of fermentation. To eliminate the random flavor of rice, brown rice is milled into 50-70% of an entire grain. Depending on the rice milling percentage, seishu is categorized into 3 grades: Daiginjo, ginjo, honjozo. Daiginjo is regarded as premium sake.

To enjoy the freshness of high-grade seishu, it is recommended to enjoy it chilled or at room temperature. The delicate aroma goes away if you heat it to a boil. On the contrary, cheaper seishu can have increased flavor when it's warmed.


Shochu is a Japanese hard liquor which is made from rice, barley and, sweet potatoes. It contains about 25-40% alcohol. It can be enjoyed on the rocks, rocks with soda or cold water. In winter, shochu split with hot water is a good way to warm yourself up.

The fermentation of shochu goes through a stepwise process with two kinds of microorganisms: koji and yeast. Once the fermentation process is complete, shochu is distilled and stored for aging in a jar which is mostly made of earthenware. After a couple of years, shochu will have a fragrant condensed aroma and mild taste.

Essential Part of Japanese Culture

Now that you know about a few of Japan’s most iconic fermented foods, why not try a little taste testing at home? In moderation, these foods will lead to a healthy diet. All you need is the ingredients, time and patience. Itadakimasu!

Umami Recipe
Umami Recipe Team

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