Miso
Miso begins with a soybean, salt, and a mold called Aspergillus oryzae. Left together, these ingredients turn into a thick paste that Japan has long treated as a seasoning, a spread, and a pickling medium. Some batches are ready in as little as five days. Others are left to ferment for several years. Sometimes rice, barley, seaweed, or other ingredients join the mix, and each choice changes the result. Descriptions of the finished paste range from salty and sweet to earthy, fruity, and savory. That range raises questions. How did a mold become a kitchen partner? Why do people in different parts of Japan prefer different colors of the same food? And how did a humble paste end up as a provision for warriors?
Long before anyone wrote the word miso, people in Japan were fermenting grain and fish. The Jōmon period, from 14,000 to 300 BC, left behind what are now called jōmon miso. They resemble the fish and soy sauces that were produced across East Asia. The exact origin of miso in Japan is still not completely clear.
The direct ancestor of the paste came from China in the third century BC. Hishio and other fermented soy foods probably arrived in Japan in the sixth century AD, at the same time as Buddhism. The early food went by the name shi.
By the Nara period, from 710 to 794, the name had become mishō, written with the characters 未醤. Hishio at that point still meant beans. It is believed that the word shifted to misho and eventually settled as miso. The Kamakura period, beginning in 1185, would show how far this fermented food had travelled.
A common meal in the Kamakura period, from 1185 to 1333, was a bowl of rice, some dried fish, a serving of miso, and a fresh vegetable.
Miso of that age looked different from today's. Until the Muromachi period, which ran from 1337 to 1573, makers left the soybeans whole, somewhat like nattō. Then Buddhist monks found that soybeans could be ground into a paste. That discovery opened new ways of using miso to flavor other foods.
In medieval times a new word appeared, temaemiso, meaning homemade miso. Because making miso is relatively simple, homemade versions spread throughout Japan.
In the Sengoku period, armies carried miso as military provisions. Making it was an important economic activity for the daimyōs of that era.
The Edo period, from 1603 to 1868, brought more names. Miso was also called hishio, written 醤, and kuki, written 豆支. Varieties suited to each local climate and culture emerged across the country.
Today most miso is made industrially in large quantities, and traditional homemade miso has become a rarity. Newer versions include pastes with added soup stock or calcium, pastes made from beans other than soy, and pastes with reduced salt for health. Every one of them, from homemade to factory-made, still begins with the same mold.
Making miso is a two-step process. First comes kōji, the starter culture. Then the kōji is combined with soybeans and usually a grain, either rice, barley, or rye, and the mixture is left to be digested by enzymes, fermented, and aged.
Kōji begins when Aspergillus oryzae is introduced onto steamed white rice. The mold comes from dried spores called tane-kōji, meaning starter koji, which are isolated from plant matter, usually rice. In the past, makers relied on spores that happened to be in the air. The culture was hard to produce that way, so tane-kōji is now added almost universally, in industrial and traditional production alike.
Tane-kōji is made much like kōji itself, with one addition. A small portion of wood ash goes into the mixture. It feeds the fungus with nutrients and encourages it to produce spores.
A. oryzae is an aerobic fungus, and it is the most active fermenting agent in kōji. It makes two families of enzymes. Amylolytic enzymes such as amylase break the starch in grain down into sugar and dextrin. Proteolytic enzymes such as protease break proteins into smaller peptides or amino acids.
The strain matters. A strain chosen for sweeter white miso would likely make more amylolytic enzymes. Soybean miso might call for a strain richer in proteolytic enzymes.
The kōji's surroundings need careful control. Temperature, humidity, and oxygen all shape mold growth and enzyme production, and good control keeps harmful bacteria from taking hold. Once the kōji reaches a desirable flavor profile, it is usually mixed with salt to halt further fermentation.
Other fungi have made kōji, but A. oryzae is the most desirable. Among its virtues, it does not produce aflatoxin. The sugars and amino acids it frees become the raw material for the reactions that give miso its smell.
The aroma of a miso decides its quality, and chemists point first to the Maillard reaction. It is a non-enzymatic reaction between an amino group and a reducing sugar. The volatile compounds it produces give miso its characteristic flavor and smell.
Two furanone compounds, abbreviated HEMF and HDMF, are described as novel flavor compounds of miso. HEMF is known for a sweet aroma. It is especially important when experts judge the aroma of rice miso.
The key to overall quality is the activity of microorganisms and their enzymes. They work on the rice, barley, and soybeans to produce pigments, flavors, and aroma compounds. Which compounds appear depends on the microorganism and on the bean or cereal, and that is how different types of miso arise.
Soybean on its own tastes relatively dull. Proteolysis of soy protein releases amino acids that give it an umami taste. Soy protein holds a substantial amount of glutamate, whose salt is monosodium glutamate, or MSG. Food manufacturers use MSG to improve the taste of their products.
The umami in MSG itself is one-dimensional. The umami in miso is multidimensional, because it comes from a myriad of amino acids and fermentation products.
Barley miso shows how particular a flavor can be. It is a traditional farmhouse variety made for personal use and often called rural miso. Domestic barley is used more than imported barley. Glutamic acid and aromatic compounds such as ferulic acid and vanillic acid give it a characteristic flavor. The same chemistry also changes the color of the paste as it ages.
Aging for more than a year is what can turn white miso red. Akamiso, or red miso, is sometimes aged that long. Through the Maillard reaction its color shifts gradually from white to red or even black. It tastes salty, with some astringency and umami, and it is often much stronger than other kinds. The depth of color depends on the soybean formula and the quantity used. Steamed soybeans generally give a deeper color than boiled ones.
Shiromiso, or white miso, is the most widely produced miso in the country. Its main ingredients are rice, barley, and a small quantity of soybeans. Adding more soybeans would make it red or brown. Its fermentation is very short compared with red miso. The taste is sweet and the umami is soft.
Third comes awasemiso, or mixed miso. It blends other varieties to cover the weak points of each. Mame miso, for example, is very salty, but mixed with kome miso it gives a mild taste.
Geography shapes the choice. In the eastern Kantō region, which includes Tokyo, the darker akamiso is popular. In the western Kansai region, around Osaka, Kyoto, and Kobe, people prefer the lighter shiromiso.
A finer breakdown follows the main ingredient. Kome miso, or rice miso, can be yellow, yellowish white, or red. The whitish kind is made from boiled soybeans and the reddish kind from steamed ones. It is eaten more in eastern Japan and in the Hokuriku and Kinki areas.
Mugi miso, or barley miso, is whitish when made in Kyushu, western Chugoku, and Shikoku. A reddish version comes from the northern Kantō area. It has a peculiar smell.
Mame miso, or soybean miso, is darker and more reddish brown than rice miso. It is less sweet, with some astringency and good umami, and it needs a long maturing time. People eat it mostly in Aichi, Gifu, and Mie prefectures.
Soybean miso without any grain is also labeled hatchō miso. It is a specialty of Okazaki in Aichi, and it has its origins in Mikawa Province during the Sengoku period. Its makers still use large wooden barrels with stones on the lids. In Sendai, the soybeans are mashed much more coarsely than in ordinary soy miso.
The ingredient list stretches far beyond soy. Makers have used barley, rice, buckwheat, millet, rye, wheat, hemp seed, and cycad. Taima is made from hemp seed, and sobamugi from buckwheat. Nari is made from cycad pulp and belongs to the Buddhist temple diet. Gokoku, meaning five-grain, combines soy, wheat, barley, proso millet, and foxtail millet. Nanban is mixed with hot chili pepper to make a dipping sauce.
Japanese misos are difficult to classify, but the usual method sorts them by grain type, color, taste, and background. Producers in other countries now also sell miso made from chickpeas, corn, azuki beans, amaranth, and quinoa.
In a traditional Japanese breakfast, plain rice and miso soup form a fundamental pair. Miso soup is the most common home for the paste, which is mixed with dashi soup stock. Much of the Japanese population eats it daily.
Miso also flavors other soups and soup-like dishes, including some kinds of ramen, udon, nabe, and imoni. The name of such a dish usually starts with miso, as in miso-udon. These dishes taste heavier and earthier than Japanese soups that are not built on miso.
Sweet miso glaze coats many traditional confections, such as mochi and dango. Its texture ranges from thick and taffy-like to thin and drippy. These treats are strongly associated with Japanese festivals, though supermarkets sell them all year.
Soybean miso is the base for misozuke, a kind of pickle. Cucumber, daikon, napa cabbage, and eggplant are the usual vegetables. The result is sweeter and less salty than the standard Japanese salt pickle.
The list of other uses runs long. Dengaku is miso sweetened with molasses and used for grilling. Yakimochi is mochi grilled over charcoal and covered in miso. Cooks also braise vegetables or mushrooms in it.
Fish or chicken can sit overnight in a mix of miso and rice wine before grilling. Corn on the cob in Japan is often coated with shiro miso, wrapped in foil, and grilled. Misoyaki is a sauce that is a variant on teriyaki. Miso also works as a dip for cucumbers, daikon, and carrots.
Okazu-miso is miso mixed or cooked with spices or vegetables. People eat it as a condiment or side dish, alongside hot rice or spread over onigiri. Cooks have one rule to follow, and it concerns the moment the pot comes off the heat.
Natural miso is alive. It holds beneficial microorganisms such as Tetragenococcus halophilus, and overcooking can kill them. For that reason, cooks add miso to soups and other dishes just before taking them off the heat. Using it with no cooking at all may be even better. It usually comes as a paste in a sealed container, and it needs refrigeration once opened.
Miso is high in protein and rich in minerals, and it played an important nutritional role in feudal Japan. Other claims have fared worse. Some studies have contradicted the idea that miso is high in vitamin B12. Some experts suggest it is a source of Lactobacillus acidophilus.
Salt raises the sharpest question. Miso is relatively high in salt, which could push up blood pressure in the small percentage of people with sodium-sensitive prehypertension or hypertension. Yet several studies point the other way. Researchers used salt-sensitive hypertensive models and analyzed long-term intake. They suggested that miso lessens the effects of salt on blood pressure.
As of 2018, interest in miso was growing well beyond Japan.
Updated
Common questions
What is miso made from?
Miso is a thick paste made by fermenting soybeans with salt and kōji, which is grown from the fungus Aspergillus oryzae. Rice, barley, seaweed, or other ingredients are sometimes added.
Why is red miso darker than white miso?
Red miso is aged, sometimes for more than a year, and the Maillard reaction gradually turns its color from white to red or black. White miso ferments for a much shorter time.
Which kind of miso do people in Tokyo and Osaka prefer?
In the eastern Kantō region, which includes Tokyo, the darker akamiso is popular. In the western Kansai region, around Osaka, Kyoto, and Kobe, the lighter shiromiso is preferred.
When should miso be added to a dish?
Add it just before removing the dish from the heat. Natural miso holds living microorganisms such as Tetragenococcus halophilus, and overcooking can kill them.
Is miso bad for blood pressure?
Miso is relatively high in salt, which could raise blood pressure in people with sodium-sensitive prehypertension or hypertension. Several studies of long-term intake suggest that miso lessens salt's effects on blood pressure.
All sources
24 references cited across the entry
- 1Global Miso Market 2018-2022Research and Markets
- 2お味噌の歴史 (The History of Miso)Yamajirushi Jyozo
- 3BookHistory of Miso, Soybean Jiang (China), Jang (Korea) and Tauco (Indonesia) (200 BC-2009)William Shurtleff et al. — Soyinfo Center — 2009
- 4BookBeans: a historyKen Albala — Berg Publishers — 2007
- 5Open innovation of Marukome and Panasonic to create "New Miso Life"Naoaki Yamamoto — 2018-03-07
- 6The origin of misoYumi Miyamoto — 2017-03-02
- 7All About Miso & Miso Soup Recipekhintan — 2020-12-02
- 8Everything You Need to Know About Miso Paste YABAI - The Modern, Vibrant Face of JapanYABAI Writers — 16 May 2017
- 10BookIndustrialization of Indigenous Fermented Foods, Revised and ExpandedKeith Steinkraus — CRC Press — 2004
- 11JournalAnalysis of the cooked aroma and odorants that contribute to umami aftertaste of soy miso (Japanese soybean paste)Yutaka Inoue — 2016
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- 14BookEncyclopedia of Food Microbiology, Volumes 1–3Richard K. Robinson — Elsevier — 2000
- 15amylolytic, adjOxford University Press
- 16BookThe book of miso. savory, high-protein seasoningWilliam Shurtleff et al. — Ten Speed Press — 2001
- 17BookThe book of miso: savory, high-protein seasoningWilliam Shurtleff et al. — Soyinfo Center — 2001
- 18Misozuke Recipe (Japanese miso pickle)Brad Harvey — 26 July 2008
- 19Vitamin B12The Vegetarian Society of the United Kingdom Limited
- 20Lactobacillus acidophilusSteven D. Ehrlich — University of Maryland Medical Center (UMMC) — 2011-05-24
- 21JournalReview of the health benefits of habitual consumption of miso soup: focus on the effects on sympathetic nerve activity, blood pressure, and heart rateKoji Ito — 2020-08-31
- 22JournalLong-term intake of miso soup decreases nighttime blood pressure in subjects with high-normal blood pressure or stage I hypertensionHiroaki Kondo et al. — November 2019
- 23JournalBlood pressure reduction by Japanese traditional Miso is associated with increased diuresis and natriuresis through dopamine system in Dahl salt-sensitive ratsDong Dong Du et al. — 2014
- 24BookHandbook of Fermented Functional FoodsEdward R. Farnworth — CRC Press — 2003