What is Miso?

Miso is one of the traditional
Japanese fermented
ingredients made from
soybeans, koji and salt.

Miso is believed to have been brought into Japan from China. It was originally a luxurious, prized food that could only be eaten by small, privileged groups of people. It was rarely consumed in the form of miso soup then, and was instead eaten as a side dish or as medicine. Around the Kamakura period (1185-1333), the samurai meal custom known as “Ichiju Issai” (literally meaning one soup, one dish) became established. Consuming miso in the form of soup was popularized, and miso became an essential part of the Japanese diet. Commoners began brewing their own miso during the Muromachi period (1333-1573), and it began to be industrially produced entering the Edo period (1603-1868). In this way, miso took root deeply among Japanese people, and is still an indispensable seasoning in Japanese cuisine today.

Although it is common to use miso and dashi together, various new ways of using miso are being created in modern times, including using it for foods other than Japanese cuisine as an all-purpose seasoning. This is due to miso’s high nutritional value, including its abundance of essential amino acids, and its effects for preserving food and making meat and fish tender.

Amino acid
composition of
soybean protein

Soybeans, an ingredient of miso, contain abundant protein. Proteins are made up of 20 kinds of amino acids. The amino acid varieties and their quantities present in soybeans are shown in the figure below. Although the protein does not have a taste, it is broken down into its amino acids through the fermentation process in which it is made into miso. As you can see in the figure below, glutamate is the most prevalent of the amino acids in soybean protein. It is followed by aspartate, which is another amino acid with umami. Umami taste intensity of aspartate has about one-tenth the umami of glutamate, so is thus quite weak. However, it is reported that the ratio of glutamate to aspartate plays a part in creating the deliciousness of food. In the soybean fermentation process, about 30% of the protein contained in soybeans is broken down into amino acids. In this way, miso that contains various amino acids, centered on glutamate that is an umami component, is made.

Koji-mold: An
essential agent for
fermenting soybeans to make
miso

Koji-mold ( Aspergillus oryzae ) is one of the main ingredients of miso. It is an indispensable component when speaking about Japanese food culture. Because food is closely related to health, it is no exaggeration to say that koji-mold has had an important presence in supporting Japan, a country where people live long lives. Japan's very humid climate is said to be suited for the growth of koji-mold, and traditional fermented foods such as miso, soy sauce, sake, amazake, mirin, and vinegar are all made using koji-mold. In October 2006, Aspergillus oryzae was designated as a "national fungus" by the Nippon Jozo Gakkai (Brewing Society of Japan) due to its longstanding contributions to Japanese food culture and expectations that it will be used in an even wider range of fields in the future.

Koji-mold is the general term for filamentous fungi, which are used to make rice koji, barley koji and soybean koji, and is a type of mold.
Various types of koji-mold are used to make miso, soy sauce, sake, and shochu ― Japanese distilled spirit.
The koji-mold’s enzymes include protease, which breaks down proteins into amino acids, amylase, which breaks down starches into sugars, and lipase, which breaks down lipids. Umami, sweet and aromatic substances are produced during the fermentation process.

During the Muromachi period about 600 years ago, a technique was created in Japan to grow different types of koji-mold separately by mixing koji-mold with charcoal. Through this, the business of selling different types of koji-mold was established, and people who produced products such as miso, soy sauce, and sake became able to make stable-quality fermented foods by acquiring koji-molds suited for the products they were making.
Shops that make and sell various types of koji-mold have been known as "moyashiya." It is said to be the world’s first bio-business, unseen anywhere else.
The koji-mold’s enzymes amylase, which breaks down starch, and protease, which breaks down proteins, work together to break down the starch into sugars and the proteins into amino acids. The soybean protein is broken down into various amino acids through the koji-mold’s protease, and glutamate, the umami substance, increases during the fermentation process.

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• Do you know what koji is in the first place? Koji is made by growing koji kabi (koji-mold) on grains such as rice, barley, and soybeans. At this time, the grains that are mixed with the koji-mold starter become rice koji if the grain is steamed rice, barley koji if it is steamed barley, or soybean koji if it is steamed soybeans. Depending on which koji-mold is added to soybeans that have been heated and softened, the completed miso is classified as rice miso, barley miso, or soybean miso. The different grains used to make koji determine what kind of koji is produced and what kind of miso is made from it. The sweetness of miso differs depending on the balance of koji and salt. Generally, the less salt is used and the higher the koji ratio to soybeans, the sweeter the miso is.
  On the other hand, if the more salt is used and there is a lower ratio of koji to soybeans, the saltier miso is produced. Rice koji is generally used most often to make miso. If the koji-mold is grown sufficiently, the rice grain changes color to white to its core, so you should try picking it up to check it.

The taste of the completed miso depends on the type of koji used.
The characteristics are as follows.

• Rice koji:

  Salty and
  sour taste

• Barley koji:

  Light and
  sweet taste

• Soybean koji:

  Rich and
  deep taste

The figure below shows the increase of various amino acids during the fermentation period. Glutamate and aspartate are amino acids with umami. You can see the increase of amino acids with umami at the beginning stage of the fermentation (about 20-35 days). On the other hand, the amino acid histidine mostly does not change after 10 days of aging.

Miso Types

Miso is often
misunderstood because
there is no
clear criteria
for it

Many fermented foods other than miso, such as soy sauce, are subject to the Japan Agricultural Standard 11JAS. However, miso is not. The reasons are because there are so many types of miso that it is difficult to make the necessary groupings to establish a standard in miso produced without heating process, yeast and lactic acid bacteria continue to live and consume the nutritional content in the miso even after it is shipped, and it is difficult to maintain the chemical analysis values that form the basis for the standard. This is why miso is a food product with no JAS standard or other clear criteria. We do not know the exact number of miso products sold throughout Japan, and recognition concerning its classification is vague. Here, we show the classification of miso according to the type of koji used. Miso is mainly classified into "rice miso (kome miso)," "barley miso (mugi miso)," and "soybean miso (mame miso)." This is the most basic way to classify miso.

Classification of
miso by koji

Miso is a complex mixture of sweet, salty, umami, sour, bitter, astringent, and other flavors. General miso products and categories used in miso competitions are divided into three kinds: low-salt (ama miso), sweet (amakuchi miso), and strong (karakuchi miso). Miso becomes more saltier the more salt is used, and sweeter the more koji is used.

Miso is divided into three categories depending on its
saltiness

In addition, miso is classified by color as white, light-colored, or red depending on various conditions such as the soybean variety used as the raw ingredient, the difference in heating method of boiling or steaming the soybeans, the amount of koji, the temperatures used for controlling the fermentation and aging processes, and whether or not it is mixed in the process. The main reason for the color difference is the aging period. The longer miso is left to age, the darker its color becomes through the Maillard reaction.

Visible color classification

Local miso
varieties
throughout
Japan

• Miso has been cultivated in the Japanese diet for over 1,300 years. Each region of Japan produces its own unique miso products according to its local ingredients, climate, eating habits and preferences. Even today, miso varieties are known by local names such as Shinshu miso, Echigo miso, Edo sweet miso, Sendai miso, Saikyo miso, and Tsugaru miso, and beloved as a “taste of one’s home town.”

• 

• 

  Hokkaido miso

  Miso with a plain taste that brings out the flavors of the ingredients.
  As Hokkaido has long had strong connections with Niigata (Echigo) and Sado, Hokkaido miso resembles Echigo miso and Sado miso. There are many local dishes cooked with miso using salmon, which is caught in great numbers in Hokkaido.

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  Tsugaru Miso

  Known as "Tsugaru Sannen (three-year) Miso,” this strong red miso is aged over a long time with a low ratio of koji-mold and high salt content. Because the Tsugaru region, which is located in Aomori Prefecture in northern Japan, used to suffer from bad harvests often in the past, it is said that production of the type of miso that keeps for a long time became popular among residents to prepare against starvation.

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  Sendai miso

  It is said that Date Masamune, a famous samurai and ruler of the Sendai domain, made miso as provisions for his army in the Warring States period (1467-1615). He continued to produce high quality miso not only for military use, but also for the development of the local industry. Sendai Miso is a traditional miso aged for a long time that has been handed down from that time.

• 

  Aizu miso

  This strong red miso that is aged over a long time period is made in the harsh climate of the Aizu Basin, where there are major temperature variations. It has a history of over 300 years.

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  Shinshu miso

  Shinshu miso has the top production volume in Japan. About 40% of the miso produced and purchased in Japan is Shinshu miso. During the period of Takeda Shingen, a powerful feudal lord whose territory included Shinshu Province, miso spread throughout the region due to the active cultivation of soybeans and Shinshu’s climate and water quality suited to cultivation.

• 

  Edo sweet miso

  This sweet red miso is made with plenty of rice koji over a short period of up to 10 days. It is also used for the regional Edo delicacies such as "Dojo-nabe" (pond loach hot pot). It has a rich sweetness and luster due to the high ratio of the rice koji.

• 

  Tokai soybean miso

  This soybean miso is known by names and brands such as "Nagoya miso," "Mikawa miso," "Sanshu miso," and "Hatcho miso," and is produced mainly in the Chukyo region in central Japan. A wide variety of dishes using soybean miso are seen throughout the region. This miso is characterized by a slight sourness and bitterness as well as its rich umami.

• 

  Saikyo miso

  Made in Kyoto, this miso is characterized by its very high ratio of rice koji and strong sweetness. This miso is indispensable for kaiseki and fucha cuisines, which developed along with the tea ceremony. Ozoni soup with this white miso is eaten at New Year's in the Kansai region.

• 

  Echigo miso, Sado miso

  There are two types of Echigo miso: strong red miso with a low koji-mold ratio and strong red miso known as "floating koji or uki koji miso." Sado miso is made with a large amount of koji-mold and is aged over a long period of time, giving it a rich umami with a subtler and milder saltiness.
  A fishermen’s dish of pollock stewed with its liver in Sado miso is a local delicacy passed down through generations.

• 

  Kaga miso

  This strong red miso aged for a long time has a history of being used as army provisions and for food preservation by the Kaga Maeda clan in Ishikawa Prefecture. Noto Peninsula and Toyama Prefecture have red miso with a large amount of water, and Fukui Prefecture has a sweet red miso that was influenced by Kyoto. Because the Hokuriku region had flourishing exchange with the Tohoku and Kansai regions, it is influenced by these regions.

• 

  Sanuki miso

  Although Shikoku belongs to the barley miso sphere, white, low-salt rice miso is also produced in the coastal areas facing the Seto Inland Sea. The rich flavor with strong sweetness of this white, low-salt miso stands alongside Kyoto’s white miso and Hiroshima’s Fuchu miso in terms of popularity. There is a zoni soup made with this white miso that contains sweet rice cakes filled with red bean paste.

• 

  Gozen miso

  It is said that the origin of the name of this miso comes from the fact that it was in feasts (gozen in Japanese) served to the feudal lords of the Hachisuka clan of Awa Province. It is said to be a sweet red miso of Tokushima Prefecture, which contains a high ratio of koji-mold and has a rich umami. The salt content is the same as strong miso, but it has a medium-strong taste if we look at miso throughout Japan.

• 

  Setouchi barley miso

  This barley miso is beloved in the region where the rice miso sphere and barley miso sphere intersect. In particular, barley miso made in Ehime Prefecture has a high ratio of mugi koji, so it has barley’s characteristic aroma and light sweetness. This miso is produced in many different varieties, such as white and light-colored rice miso and barley miso, in small areas in the prefecture.

• 

  Fuchu miso

  Low-salt miso in white and cream colors made with peeled soybeans. It is appreciated for its delicate and savory flavor and richness, and is the second-most representative white low-salt miso after Kansai white miso. Its deliciousness began to be known around Japan from the Edo period.

• 

  Kyushu barley miso

  This miso is mainly made in Kyushu, where barley miso is common. Because Kyushu has a warm climate, the aging period for this miso is relatively short. There are many miso varieties still known by the names of the old provinces of Japan, such as Higo miso in Kumamoto Prefecture and Satsuma miso in Kagoshima Prefecture.

• 

  Sotetsu miso

  This miso is made on Agunijima Island and Amami Oshima Island in Okinawa, the southernmost prefecture. Japanese sago palm cones are pulverized and mixed together with unpolished rice, barley, and other ingredients to make koji, which is then mixed with soybeans, salt, and sweet potato. Andamisu (lard miso) is an Okinawan traditional preserved food made by mixing miso and lard.

Glutamate, the umami
substance of miso

The results of free amino acids analysis in various commercially-available miso are shown in the figure. Glutamate is the most abundant amino acid in all the miso varieties. Total amount of amino acids in white miso, which has a shorter fermentation period, is smaller than others. The longer the fermentation period, the more amino acids. Even if the same soybeans are used as a raw material, the proportion of amino acids differs depending on the type of koji and the fermentation period.

Miso varieties used in this
analysis

Free amino acids in miso
varieties

Miso that has
supported the
minds and health
of Japanese people

What foods are made with miso in Japan? If you are asked that question, you will immediately think of the major staple of miso soup. The basic meal that Japanese people have become accustomed to is white rice and miso soup, right? In terms of miso being a food that can be said to be the origin of Japanese food, it is not possible to leave out miso soup when we talk about miso. No matter whether it is classified as rice miso, barley miso, soybean miso, or if it is white or red, all of the miso varieties can be used in miso soup.

If there is miso soup with many ingredients, it will allow the diner to consume many warm vegetables and provide a nutritional balance. In Japan, where there are four distinct seasons, you can enjoy the flavors of seasonal ingredients in miso soup.

Although the ways of making miso soup differ slightly according to the ingredient, they are basically the same. Below is a very common recipe for miso soup.

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  1. Preparing the dashi and ingredients

  Prepare the dashi according to the method introduced for "basic dashi," or to prepare it more easily, soak the kombu in water for about 30 minutes in a bowl. Cut the ingredients in the meantime.

• 

  2. For ingredients that are
  easy to cook, add them after
  bringing the dashi to a boil

  First, put vegetables that are hard to cook, such as root vegetables, with the prepared dashi into a pot together with meat, fish, and other dashi-producing ingredients. After the dashi in the pot is brought to a boil, add the ingredients that are easy to cook, such as leafy vegetables, seaweed, and tofu that tends to fall apart while cooking.

• 

  3. After the ingredients are cooked, lower the heat and
  add the miso

  Put the miso in a ladle, scoop out the proper amount of dashi in the ladle, and dissolve the miso until there are no clumps using long chopsticks, a small whisk, or other implement. When the miso has dissolved into the dashi to form a liquid, add it to the pot.

• 

  4. Turn off the heat at the niebana" timing just before
  the mixture boils, pour the
  soup into a bowl, and serve

  "Niebana" (boiling flower) refers to the state of the mixture just before it boils when the ingredients and miso dissolved in the soup are quivering. It seems that it is called this because it looks like a flower is blooming lightly from the bottom of the pot. Be careful not to leave the mixture boiling because it will ruin the aroma of miso. When you have confirmed that the mixture has reached "niebana," turn off the heat and serve it in a bowl.

Umami of dashi
and miso soup

A major characteristic of miso soup is that it is a satisfying soup made without the use of animal fats such as cream and butter. Dashi contains glutamate and aspartate derived from kombu (kelp). Because glutamate and aspartate are both amino acids with umami, kombu dashi is a very simple liquid with umami. If you add miso, you also blend in the various amino acids contained in miso, which yields a soup rich with amino acids.

If you compare miso soup and chicken soup, you can see that miso soup contains more amino acids, including umami-rich glutamate. As miso soup contains a total of about 340 mg of free amino acids while chicken soup contains about 212 mg, you can see that miso soup contains more free amino acids. Also, you can see in the pie chart below that the ratio of glutamate and aspartate among the free amino acids is higher in miso soup than chicken soup. The abundant amino acids in dashi and miso create the flavor of satisfying miso soup.

Amount of free amino acids in
miso soup and chicken soup ©umami information center

• Miso soup

  

• Chicken soup

  

• 

• 

Miso soup in
"Ichiju Sansai",
One
Soup with
Three Dishes

life expectancy in 2016. It aims to lengthen people’s healthy lives by three years by 2040, and focuses on improving citizens’ lifestyles, among them eating habits. It stipulates that people should eat three meals per day regardless of their age, that two of the three meals should have a staple food, main dish, and side dish, and that people should think about lowering their salt intake. "Ichiju Sansai" (one soup with three dishes), a Japanese meal style passed down from long ago, is gaining renewed attention as a meal style that provides an excellent nutritional balance. It is said that Japanese people consumed the most ideal meals in 1975. That was when Ichiju Sansai was the standard meal style. Let’s try focusing on soup, in particular, from the perspective of umami. In usual Japanese meals, the soup is mainly miso soup. Miso soup has low energy density (energy/weight) and is a satisfying dish. Although there may be some people who are worried that consuming soup can lead to the intake of too much salt, soup can be savored with lower salt content by using umami-rich dashi.

Furthermore, in terms of health, it is reported that the more you consume soup, the more of a tendency you have to not become obese. In an epidemiology study conducted in Kyushu area, as a result of examining the connection between the frequency of consuming soup (mainly miso soup and other soup varieties) and BMI, it was reported that people who did not consume soup at all made up a higher percentage of those with a BMI of over 27, while people who made it a habit to eat soup at three meals everyday made up a higher percentage of those with a BMI of under 23. In Italy, Portugal, and the United States as well, it is reported that the more frequently people consume soup, the lower their BMI tends to be.

Miso soup contains both the umami component in dashi as well as miso, so you will feel satisfied if you consume the umami-rich soup. Furthermore, when soybeans are used as an ingredient of a dish, digestion and absorption of protein will not be very good. In the case of miso, however, the protein contained in the soybeans has already been digested into the amino acids through the enzymes of the koji-mold. The starch of rice, an ingredient of miso, is also broken down into glucose by the enzymes, so miso itself is already a digested food. Thus, it can be said that miso is an excellent nutritional supplement for the elderly and sick people whose digestion functions tend to decline.

Although you might not usually be aware of the dashi in miso soup, you should aim to consume miso soup rich in dashi and filled with vegetables every day.

The connection between pickling
with miso and umami

Although Japan has a culture of eating raw fish such as in sashimi and sushi, it also has a traditional technique of pickling marine products in miso, and thereby enhancing their shelf life and making them more delicious. The figure below shows the increase of amino acids that yield sweetness and umami in sablefish while it is pickled in miso, as well as the decrease in amino acids in the miso marinade. Miso weighing half the weight of the sablefish slices is spread around the cut slices, which are pickled for five days.

You can see that the amino acids in the miso are transferred to the sablefish in a few days after the fish has been pickled. In this way, it is not only possible to preserve the fish by pickling it in salty miso, but also to enjoy a different flavor compared to the raw fish due to the umami and sweet components of the miso permeating the fish.

Changes in the amount of amino
acids with umami and
sweetness
when sablefish is pickled in miso

Changes in the free amino acids
in the miso marinade when
sablefish is pickled in miso