Figaro Shakes
Cultural Ferment

Doenjang: How Korean Soybean Paste Is Made, and Doenjang vs Miso

By Updated 2 min read

Master doenjang, the deep umami soul of Korean cuisine. This complete guide covers the 3,000-year history, the two-stage meju fermentation science, how to make traditional doenjang at home, and how to use it in doenjang jjigae, marinades, and beyond.

At a glance

Doenjang is Korea's fermented soybean paste. Cooked soybeans are formed into meju blocks and fermented for weeks by Bacillus bacteria and molds, then soaked in strong salt brine: the liquid becomes ganjang (soy sauce) and the mashed blocks become doenjang, aged for months or more. Meju is the stage most vulnerable to aflatoxin molds, so home cooks often start from bought meju.

  • Two stages: meju (fermented soybean blocks), then brining, which yields doenjang and ganjang.
  • Early meju is dominated by Bacillus bacteria and Mucor molds; Aspergillus appears later.
  • Most aflatoxin contamination happens at the meju stage; a year of fermentation cut spiked aflatoxin by ~98%.
  • In 36 cottage-made doenjang, all contained histamine and tyramine; 3 exceeded Korea's B. cereus limit.
  • Differs from miso: wild-fermented meju instead of cultivated koji.

Ferment profile

Origin
Korea
Fermentation
Mixed (lactic + alcoholic)
Main microbes
Bacillus (e.g. B. velezensis), Mucor, Aspergillus and other molds; Enterococcus and lactic acid bacteria; yeasts
Live cultures
Depends on preparation
Alcohol
None / trace

Doenjang (된장) is Korea’s fermented soybean paste: thick, brown, salty and deeply savory, the base of doenjang-jjigae (soybean paste stew) and, mixed with gochujang, of ssamjang for lettuce wraps. It’s made in two stages, and the same process also produces Korean soy sauce, ganjang.

How Doenjang Is Made

  1. Meju: cooked soybeans are mashed, shaped into blocks, dried and hung – traditionally tied with rice straw – to ferment for weeks. In a study following traditional meju, Bacillus bacteria and Mucor molds dominated early, inside and out; other bacteria grew in the airless interior, and molds such as Aspergillus took over later. Most of the bacteria came from the molding equipment, and the molds from the shelves, air and straw (Jung et al., 2014).
  2. Brining: the dried meju blocks go into a crock (onggi) of strong salt brine for several weeks. The liquid becomes ganjang; the softened blocks are mashed with salt into doenjang.
  3. Aging: doenjang is then aged for months or years, getting darker and more pungent.

Safety: Aflatoxin, Bacillus cereus and Amines

  • Aflatoxin: meju is highly vulnerable to aflatoxin-producing Aspergillus flavus, and most aflatoxin contamination in doenjang happens at the meju stage. Encouragingly, when researchers spiked doenjang with aflatoxins and a toxin-producing mold, a year of fermentation reduced total aflatoxin by about 98%, thanks to native microbes in the paste (Kumar et al., 2022).
  • Bacillus cereus: in 36 doenjang products from Korean cottage producers, 3 exceeded Korea’s limit for this food-poisoning bacterium (Bahuguna et al., 2023). Doenjang is normally cooked, as in stew, which helps.
  • Biogenic amines: the same samples contained 68–2,557 mg/kg of biogenic amines, and every one contained histamine and tyramine (Bahuguna et al., 2023). People taking MAOI antidepressants, who are advised to limit tyramine-rich foods, should check with their doctor (Gardner et al., 1996).

Because meju is where the mold risk lies, our home card starts from bought meju blocks – a common way to make doenjang and ganjang at home – rather than from raw soybeans.

Doenjang vs Miso

Both are salty soybean pastes, but they’re made differently. Japanese miso uses koji – grain deliberately grown with one mold, Aspergillus oryzae – mixed straight into the soybeans, so it’s smoother and often sweeter. Doenjang starts from meju fermented by a mix of wild bacteria and molds, then brined, so it’s chunkier, earthier and stronger. Neither is clearly “healthier”: both are high in salt and are used in small amounts; doenjang tends to be the more pungent and is more often used cooked. Natto, the other common comparison, is whole soybeans fermented by Bacillus and eaten as a dish rather than a paste – see our fermented soybean guide and natto. Korea’s quick soybean ferment is cheonggukjang.

Recipe: Doenjang and Ganjang From Bought Meju

Makes
About 2.5 kg doenjang and 3–4 litres ganjang
Hands-on
60 min
Fermentation
6–8 weeks in brine, then 2+ months aging
Salt
Brine of about 18% salt (1.1 kg salt in 6 litres water)
Temperature
Outdoors or a cool, airy spot; protect from rain
Difficulty
Moderate

Equipment

  • 8–10 litre onggi crock or food-grade container with a lid and a cloth cover
  • Scale
  • Fine cloth for straining
  • Large pot for boiling the ganjang

Ingredients

  • 2 kg (about 4 blocks) dried meju blocks (bought from a Korean grocer)
  • 6 litres water (boiled and cooled)
  • 1.1 kg coarse sea salt (plus extra for the doenjang)
  • 3–4 dried red chilies and a few dried jujubes (optional, traditional)

Method

  1. Brush the meju blocks clean under running water and let them dry in the sun or an airy spot for a day.
  2. Dissolve the salt in the boiled, cooled water and let any sediment settle.
  3. Put the meju in the clean crock, pour over the clear brine so the blocks float, and add chilies and jujubes if using.
  4. Cover with a cloth and lid; leave in a sunny, airy spot for 6–8 weeks, opening the lid on dry days.
  5. Lift out the softened meju. Strain the liquid: this is ganjang – bring it to the boil, skim and bottle it when cool.
  6. Mash the meju with a little salt (and some ganjang if dry), pack it into a clean crock, smooth and salt the surface, and age at least 2 months before using.
  7. Discard batches that turn slimy or grow fuzzy colored mold inside the paste; keep finished doenjang refrigerated.

Frequently asked questions

What is doenjang?

Korea's fermented soybean paste, made by brining blocks of fermented soybeans (meju) and aging the mashed blocks; the brine becomes Korean soy sauce.

Doenjang vs miso: which is healthier?

Neither clearly wins. Both are salty pastes used in small amounts. Miso is made with cultivated koji; doenjang with wild-fermented meju, which makes it stronger and earthier.

Is doenjang the same as miso?

No. They're cousins: miso mixes koji directly into soybeans, while doenjang is made from meju blocks soaked in brine. Doenjang is chunkier and more pungent.

What is meju?

Blocks of cooked, mashed soybeans dried and fermented for weeks by Bacillus bacteria and molds – the starter for doenjang and ganjang.

Is the mold on meju safe?

Molds are part of meju fermentation, but meju is also where aflatoxin-producing molds can grow, which is why buying meju from a reputable source is the safer route.

How do you use doenjang?

Dissolve it into doenjang-jjigae (soybean paste stew) or soups, mix it with gochujang for ssamjang, or use it in marinades and dressings.

How long does doenjang last?

Months in the fridge in a closed container; it keeps darkening and deepening. Discard it if it turns slimy or grows fuzzy mold inside.

Sources

  1. Jung JY, Lee SH, Jeon CO (2014). Microbial community dynamics during fermentation of doenjang-meju, traditional Korean fermented soybean. Int J Food Microbiol 185:112–120. Link
  2. Kumar V et al. (2022). Aflatoxin reduction and retardation of aflatoxin production by microorganisms in doenjang during a one-year fermentation. J Fungi 8(2):190. Link
  3. Bahuguna A et al. (2023). Safety analysis of Korean cottage industries' doenjang, a traditional fermented soybean product: a special reference to biogenic amines. Foods 12(22):4084. Link
  4. Gardner DM et al. (1996). The making of a user friendly MAOI diet. J Clin Psychiatry 57(3):99–104. Link
#East Asia
Share:

More Global Fermented Foods