# Miso (味噌)

**Miso** (味噌) is a Japanese fermented paste made principally from soybeans, combined with a grain or soybean koji (a mold-cultured starter), and salt, and matured into a savory or sweet-salty seasoning used above all in miso soup<sup>[1](https://kotobank.jp/word/%E5%91%B3%E5%99%8C-138723)</sup>. It is one of the grain-based fermented seasonings, alongside soy sauce, vinegar, and mirin, that anchor Japanese cooking<sup>[2](https://www.maff.go.jp/j/keikaku/syokubunka/traditional-foods/bunrui/shouyu-miso.html)</sup>.

| Key fact | Detail |
|---|---|
| Definition | Steamed, mashed soybeans fermented with koji and salt; classified by koji grain into rice miso (米味噌), barley miso (麦味噌), and soybean miso (豆味噌)<sup>[1](https://kotobank.jp/word/%E5%91%B3%E5%99%8C-138723)</sup> |
| First Japanese record | The Taihō Code of 701 lists a seasoning called 未醤 (miso) alongside hishio and kuki, produced at the court's shō bureau<sup>[3](https://kotobank.jp/word/%E3%81%BF%E3%81%9D-1597489)</sup> |
| Fermentation | Two-stage process: koji grown with *Aspergillus oryzae* for 40–48 hours, then a second bacterial and yeast fermentation of the salted mash lasting from days up to 2 years<sup>[4](https://onlinelibrary.wiley.com/doi/10.1111/1750-3841.15773)</sup><sup> • </sup><sup>[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9731531/)</sup> |
| Key microbes | *Aspergillus oryzae* and the yeast *Zygosaccharomyces rouxii* dominate; the lactic acid bacterium *Tetragenococcus halophilus* is detected in commercial samples<sup>[6](https://scijournals.onlinelibrary.wiley.com/doi/10.1002/jsf2.112)</sup> |
| Modern use | By the year 2000, 90% of miso used in Japan went into soup<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup> |
| Industrial scale | The producer Marukome makes 108,000 tons of miso per year<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup> |

## Definition and classification

Miso is made by steaming and crushing soybeans, adding koji and salt, and fermenting the mixture<sup>[1](https://kotobank.jp/word/%E5%91%B3%E5%99%8C-138723)</sup>. The koji grain determines the main type: rice miso, barley miso, or soybean miso, the last made from soybeans and koji mold alone<sup>[1](https://kotobank.jp/word/%E5%91%B3%E5%99%8C-138723)</sup><sup> • </sup><sup>[8](https://www.maff.go.jp/j/shokusan/gaisyoku/attach/pdf/inbound30-13.pdf)</sup>. Within rice miso, salt content further divides the types into sweet, semi-sweet, and salty versions in white or red colors; barley miso divides into semi-sweet and salty<sup>[2](https://www.maff.go.jp/j/keikaku/syokubunka/traditional-foods/bunrui/shouyu-miso.html)</sup>. Color differences arise from the length of maturation<sup>[2](https://www.maff.go.jp/j/keikaku/syokubunka/traditional-foods/bunrui/shouyu-miso.html)</sup>. Flavor also varies with the ratio of koji to soybeans, salt concentration, and fermentation time<sup>[4](https://onlinelibrary.wiley.com/doi/10.1111/1750-3841.15773)</sup>.

## History

**Origins.** Records from around 2000 BCE in China describe a seasoning considered a precursor of miso, and fermented seasonings called shō (醤) and shi (豉) reached Japan from China directly or via the Korean Peninsula shortly before the [Nara period](https://www.edgepedia.org/nara-period)<sup>[3](https://kotobank.jp/word/%E3%81%BF%E3%81%9D-1597489)</sup>. One theory holds that miso was transmitted from Goguryeo (Korea) in 666 CE, in the reign of [Emperor Tenji](https://www.edgepedia.org/emperor-tenji)<sup>[2](https://www.maff.go.jp/j/keikaku/syokubunka/traditional-foods/bunrui/shouyu-miso.html)</sup>; a Korean-language study traces the name to the Goguryeo word /miəsɔ/, rendered into Sino-Japanese reading<sup>[9](https://journal.kci.go.kr/cajjso/archive/articleView?artiId=ART001742147)</sup>. Scholars cannot say with certainty whether miso came to Japan from Korea or China, evolved within Japan, or arose from all three routes<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup>.

**Court and medieval periods.** The Taihō Code of 701 records the seasoning 未醤, produced at the shō bureau of the court kitchen, and shops in [Heian-kyō](https://www.edgepedia.org/heian-kyo) sold it<sup>[3](https://kotobank.jp/word/%E3%81%BF%E3%81%9D-1597489)</sup>. The character 噌 was created in Japan and is used only in the word 味噌<sup>[10](https://www.maff.go.jp/j/keikaku/syokubunka/traditional-foods/files/user/pdf/an_Introduction_to_Japanese_fermented_foods_part2.pdf)</sup>. In the [Kamakura period](https://www.edgepedia.org/kamakura-period), Zen temples produced soybean products in quantity; the monk Kakushin is credited with bringing the recipe for Kinzanji miso from China to Kishu (Wakayama)<sup>[3](https://kotobank.jp/word/%E3%81%BF%E3%81%9D-1597489)</sup>. During the [Sengoku period](https://www.edgepedia.org/sengoku-period) miso was valued as military provisions, with domainal products such as Takeda's jinya miso and Uesugi's Echigo miso, and Date Masamune built a storehouse for mass-producing military miso<sup>[3](https://kotobank.jp/word/%E3%81%BF%E3%81%9D-1597489)</sup>.

**Edo period onward.** Commercial-scale production began in the early [Edo period](https://www.edgepedia.org/edo-period): soybean miso in Mikawa from 1625 and production at the Sendai domain's miso storehouse from 1645<sup>[1](https://kotobank.jp/word/%E5%91%B3%E5%99%8C-138723)</sup>. Before soy sauce spread in the Edo period, miso was the most important seasoning in Japan<sup>[1](https://kotobank.jp/word/%E5%91%B3%E5%99%8C-138723)</sup>. By the 18th century soy sauce had largely replaced miso as the flavoring in urban areas, while rural areas kept miso as the seasoning of choice into the late 20th century<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup>. By the end of World War II more than 5,500 production sites existed across Japan<sup>[1](https://kotobank.jp/word/%E5%91%B3%E5%99%8C-138723)</sup>.

## Production

Miso production is a two-stage fermentation<sup>[4](https://onlinelibrary.wiley.com/doi/10.1111/1750-3841.15773)</sup>. First, steamed rice, barley, or soybeans are inoculated with *Aspergillus oryzae* and held for 40–48 hours to make koji, the starter culture whose enzymes decompose starches and proteins<sup>[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9731531/)</sup><sup> • </sup><sup>[11](https://www.famic.go.jp/english/jas/_doc/jas0022.pdf)</sup>. The koji is then mixed with steamed, ground soybeans and salt, sometimes with a little seed miso from the previous batch, and packed into vessels to ferment<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup>.

In the second stage, the koji enzymes break rice starch into sugar and soybean protein into amino acids, the source of umami; lactic acid bacteria then produce lactic acid from the sugars while yeasts multiply and produce ethanol<sup>[2](https://www.maff.go.jp/j/keikaku/syokubunka/traditional-foods/bunrui/shouyu-miso.html)</sup>. Maturation ranges from a few days to two years, producing the differences in flavor and color<sup>[2](https://www.maff.go.jp/j/keikaku/syokubunka/traditional-foods/bunrui/shouyu-miso.html)</sup>. Seawater salt is advised for manufacturing because its magnesium and calcium benefit the fermentation<sup>[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9731531/)</sup>.

**Microbial community.** Studies of miso samples identify *A. oryzae* and the osmophilic yeast *Zygosaccharomyces rouxii* as the predominant fungi<sup>[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9731531/)</sup><sup> • </sup><sup>[6](https://scijournals.onlinelibrary.wiley.com/doi/10.1002/jsf2.112)</sup>. Metagenomic analysis of commercial miso detected the lactic acid bacterium *Tetragenococcus halophilus*, though culture-dependent methods miss unculturable organisms and may not show the full microbial complement<sup>[6](https://scijournals.onlinelibrary.wiley.com/doi/10.1002/jsf2.112)</sup>. A 2021 review notes that despite the importance of microorganisms in miso production, little research has characterized the process<sup>[4](https://onlinelibrary.wiley.com/doi/10.1111/1750-3841.15773)</sup>.

## Regional varieties

Regional conditions of climate, ingredient supply, and eating habits produced many local misos<sup>[1](https://kotobank.jp/word/%E5%91%B3%E5%99%8C-138723)</sup>. Japan's miso map distinguishes rice miso, soybean miso, and barley miso areas<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup>. Named varieties include Tsugaru miso, a salty long-fermented rice miso from Aomori; mildly sweet Saikyo miso of Kyoto, rich in rice koji; red-brown Hatcho (Haccho) miso of Nagoya, a soybean miso weighted with rocks for two and a half years; Shinshu miso of Nagano, light-colored and savory; and the barley misos of Kyushu<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup><sup> • </sup><sup>[12](https://www.maff.go.jp/j/shokusan/export/e_info/attach/pdf/koho_sizai-1.pdf)</sup>. Soybean miso is fermented longest, two to three years, and is dark and deeply flavored<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup>.

## Use and nutrition

[Miso soup](https://www.edgepedia.org/miso-soup) became a fixture of daily Japanese life after it spread in the [Muromachi period](https://www.edgepedia.org/muromachi-period) (1336–1573), when miso soup parties popularized it<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup>. By 2000, 90% of miso used in Japan went into soup<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup>. Miso is high in amino acids, including glutamic acid, and contains [B vitamins](https://www.edgepedia.org/b-vitamins), vitamin E and K, folic acid, dietary fiber, and essential minerals<sup>[7](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)</sup>. Sensory research on 26 competition misos from Akita found that reddish-brown color, higher acid content (except lactic acid), and higher amino acid content correlated with better quality ratings<sup>[13](https://www.tandfonline.com/doi/full/10.1080/00032719.2019.1570244)</sup>.

## Innovation beyond soybeans

Chefs and researchers have extended the miso method to new substrates. A study producing eight novel misos at the Copenhagen restaurant [Noma](https://www.edgepedia.org/noma-restaurant) used yellow peas, Gotland lentils, fava beans, rye bread, and soybeans; metabarcoding and metagenomics showed the novel misos contain a greater range of microbes than currently described for miso, and the yellow pea misos were notably similar in composition to traditional soybean versions, suggesting a viable alternative<sup>[14](https://www.sciencedirect.com/science/article/pii/S096399692400560X)</sup>.

## References

1. [味噌, デジタル大辞泉・世界大百科事典・山川日本史小辞典, コトバンク](https://kotobank.jp/word/%E5%91%B3%E5%99%8C-138723)
2. [醤油、味噌、その他調味料, にっぽん伝統食図鑑, 農林水産省](https://www.maff.go.jp/j/keikaku/syokubunka/traditional-foods/bunrui/shouyu-miso.html)
3. [みそ, 日本大百科全書(ニッポニカ), コトバンク](https://kotobank.jp/word/%E3%81%BF%E3%81%9D-1597489)
4. [Allwood et al. (2021). Fermentation and the microbial community of Japanese koji and miso: A review. Journal of Food Science.](https://onlinelibrary.wiley.com/doi/10.1111/1750-3841.15773)
5. [Miso: A traditional nutritious & health-endorsing fermented product, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC9731531/)
6. [Allwood et al. (2023). Microbial ecology of Australian commercial rice koji and soybean miso. JSFA Reports.](https://scijournals.onlinelibrary.wiley.com/doi/10.1002/jsf2.112)
7. [Secrets of Japanese Miso pamphlet, 認定味噌鑑定士協会 (Miso sommelier association)](https://miso.or.jp/misoonline/wp-content/uploads/pdf/Miso_pamph19jan08.pdf)
8. [調味料、香辛料について伝える, 農林水産省](https://www.maff.go.jp/j/shokusan/gaisyoku/attach/pdf/inbound30-13.pdf)
9. [Study on etymology of Miso: Sino-Japanese & Sino-Korean transliteration of Goryeo Miso, 日本硏究](https://journal.kci.go.kr/cajjso/archive/articleView?artiId=ART001742147)
10. [Chapter 3: Learn about Typical Japanese Fermented Foods, 農林水産省](https://www.maff.go.jp/j/keikaku/syokubunka/traditional-foods/files/user/pdf/an_Introduction_to_Japanese_fermented_foods_part2.pdf)
11. [Japanese Agricultural Standard for miso, FAMIC](https://www.famic.go.jp/english/jas/_doc/jas0022.pdf)
12. [Diversity of WASHOKU, 農林水産省](https://www.maff.go.jp/j/shokusan/export/e_info/attach/pdf/koho_sizai-1.pdf)
13. [Chen et al. (2019). Effect of the Chemical Composition of Miso Upon the Sensory Evaluation. Analytical Letters.](https://www.tandfonline.com/doi/full/10.1080/00032719.2019.1570244)
14. [Novel misos shape distinct microbial ecologies: opportunities for flavourful sustainable food innovation. Food Research International.](https://www.sciencedirect.com/science/article/pii/S096399692400560X)

---
*Topic: Encyclopedia › Life and health › Applied biology and nonhuman health › Biotechnology and biological production › Bioprocess engineering and biomanufacturing › Fermentation and industrial microbiology › Industrial food fermentation*

*Initially written Sep 17, 2026 · Reviewed: Sep 18, 2026; Oct 21, 2026 · Edited: Sep 18, 2026; Oct 21, 2026 · Last review: Oct 21, 2026*

*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*

License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license