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Our current Feature series introduces just a few of the versatile fermented foods, seasonings and drink that help to define Japan’s unique cuisine: soy sauce, miso, mirin, sake and tsukemono (pickles). Following on the previous theme of soy sauce, this issue examines miso in its myriad forms.

Origins of Miso

Rice and soup are inseparable elements of the classic Japanese meal—and the soup that always comes to mind is miso soup, known as miso shiru. Miso is used in a variety of different ways and appears in countless Japanese dishes: for example, grilled black cod marinated in miso (gindara-no- yuan-yaki); mackerel simmered in miso (saba-no-miso-ni); and skewered, grilled tofu coated with a warm miso glaze (tofu dengaku).

The history of miso in Japan is centuries old. It is known that miso was included in taxes paid in kind during the eighth century, and that miso as we know it today was marketed by the twelfth century. Looking further back, however, the roots of miso are believed to have developed in China before it was introduced to Japan during the seventh century.

As miso came to be made throughout the Japanese archipelago, it evolved and began to vary widely in color, flavor and other properties as it was made from raw materials and methods suited to each local region. And as it evolved, the miso of Japan grew clearly distinct from the seasoning made in China.

Miso Varieties and Colors

The three main types of Japan’s miso are rice (kome) miso, barley (mugi) miso and soybean (mame) miso. The main ingredient of all of these miso types is soybeans, but they are categorized by the type of fermentation agent used: Rice miso is made with rice koji (fermentation starter); barley miso substitutes barley as the agent; and the fermentation process of soybean miso starts with soybean koji. All of these miso varieties are made using similar production processes and use soybean and salt.

Miso is also differentiated by color as either aka, a reddish or dark brown miso, or shiro, which includes white or yellow miso. These color distinctions are the outcome of the strength of the aminocarbonyl or so-called Maillard reaction, which is the result of the combination of amino acids and sugars during the fermentation and aging process.

Aka miso is higher in salt content and rich in amino acids and other nutrients, the result of the breakdown of soybean proteins—and therefore, it is particularly rich in umami.

Rice miso is considered the most popular type of miso in Japan, accounting for some 80 percent of all miso consumed here. A wide variety of rice miso is available, and among these, the reddish and strong-flavored shinshu miso is used widely in most households. Shiro miso, which comprises the white and paler varieties of rice miso, possesses a lower salt content that reveals the sweetness of the rice koji. This is the miso used to make the miso-marinated grilled black cod mentioned above. Shiro miso is preferred in the Kansai area surrounding Kyoto and Osaka; but even in Kyoto, this miso usually appears only on special occasions, as during the New Year, when it is used to make zoni soup.

With its distinctive sweet barley flavor, barley miso, which is also reddish in color, is consumed on the southern islands of Kyushu and Shikoku, and in Japan’s southwestern Chugoku region.

Soybean miso is dark brown in color and has a strong taste. The best-known type of soybean miso is hatcho miso, made in central Japan’s Aichi Prefecture. It requires a long aging process, and is prized for its bitter flavor and umami.

The Role of Miso

Today’s Japanese cuisine usually features side dishes which complement rice, and the role of miso is primarily that of a seasoning. From ancient times until the early Edo era (1603-1867), however, miso was an actual side dish that provided a major source of protein; and as a preserved food, it was also carried by wartime troops.

This made great sense in terms of nutrition, because miso is rich in valine, an indispensable amino acid not found in rice, staple of the early diet. This ancient miso side dish, name miso, was chunky. In contrast to the paste-like consistency of today’s miso, its barley grains or soybeans were left uncrushed and so could be eaten easily with chopsticks. Today’s most popular name miso is kinzanji miso, which is still enjoyed as a side dish.

To add further to the tremendous diversity in the world of miso, it was also once customary for every household to have its very own special recipe for miso, one to boast about. There is no doubt that this is the origin of the Japanese expression, temae miso—to sing one’s own praises. Today, it may be rare for people to make their own miso, yet the flavor of a particular miso may now and again remind some of the taste of home.

Author's profile

Hisakazu Iino was born in 1952. A 1975 graduate of the Tokyo University of Agriculture, since 1997 he has been a professor in the Graduate School of Science for Living Systems at Showa Women’s University. As a specialist in applied microbiology, Dr. Iino studies the interaction of human intestinal microorganisms. He also serves as an advisor to the Pharmaceutical Affairs and Food Sanitation Council, Ministry of Health, Labour and Welfare.