What Is Fermented Food?

By Lessley Anderson

Fermented things can be the kinds of food that people refer to as “acquired tastes.” But some of the most common things we eat and drink are fermented. The words aged and cured should be your first clue.

Fermentation is a process in which food is exposed to bacteria and yeasts, either via inoculation or naturally through the air. Beneficial microorganisms beat out the kind that can kill you, and eat up the carbohydrates in the food. The results are interesting flavors, textures, and smells. Before refrigeration, curing meats, pickling vegetables, and clabbering milk was the only way to extend the life of perishables. And if fermented foods haven’t been cooked, they are really good for you (cooking kills off the beneficial bacteria).

Here are 24 fermented foods, some of which you might eat every day and others that are less common. For more on fermentation, check out our Pickles Obsessive video, read our Q&A with home fermentation expert Sandor Ellix Katz, and see how simple making your own yogurt can be.

01 Coffee

Wild yeasts and bacteria from the air eat the slimy layer, called mucilage, still covering the beans after picking. The fermentation deepens the flavor and body of the beans.

02 Cheese

Not all cheese is fermented (paneer, for example). For those that are, bacteria are added to give cream or milk a sour flavor. After the curds and whey are separated and the cheese is formed into a solid shape, it’s inoculated with specific kinds of mold to make specific kinds of cheese (like blue cheese) and fermented (aged) again. Try an easy recipe for Creole Cream Cheese.

03 Yogurt, Sour Cream, Cultured Buttermilk, Crème Fraîche

Milk or cream is exposed to souring bacteria, either by inoculation or through the air.

04 Chocolate

After cocoa beans are picked, the pulp surrounding them ferments, darkening the beans beneath and mellowing their flavor.

05 Wine

Yeast is added to crushed grapes, or naturally occurring yeasts already on the grape skins are allowed to thrive, and they convert the juice’s sugar to alcohol.

06 Beer

Yeast is added to grains that have been heated, soaked, and strained (leaving a sweet, grainy liquid called wort), which converts the sugars to alcohol. Some beers, like Belgian lambics, use naturally occurring bacteria and yeasts from the air.

07 Charcuterie (Country Ham, Salumi, Etc.)

Meat is heavily salted, sometimes with curing salts containing nitrates, then hung in a cool, well-ventilated place to age. The salt and nitrates discourage harmful bacteria (like those that cause botulism) and encourage beneficial ones. Dry aged beef is also mildly fermented, having hung in the open air (but without salt).

08 Vanilla

Young beans are soaked, dried, and exposed to the air for several months to cure, whereby their rich flavor develops.

09 Vinegar

A starter bacterial culture called a mother is introduced to alcohol (beer and wine are most common), which converts it to acetic acid.

10 Bread

Yeast is introduced to flour and ferments the carbohydrates, leaving behind carbon dioxide, which leavens the bread. Sourdough bread also contains a souring bacterium present in the starter. Artisan Bakers founder Craig Ponsford talks about starters in this Obsessives video.

11 Pickles, Sauerkraut, and Kimchee

Fresh vegetables are mixed with salt, packed into airtight containers, and aged. Bacteria naturally present on the vegetables’ skins help create a kind of vinegar, transforming the vegetables. Not to be confused with vinegar pickles (the kind you typically find in grocery stores).

12 Fish Sauce

Fish is salted, aged, and pressed, then the rotting fish juice is mixed with spices to create this staple Southeast Asian condiment.

13 Fermented Fish (a.k.a. Rakfisk)

Especially popular in Scandinavia. Trout, char, or salmon is packed in salt and left for anywhere from 24 hours to a couple of months, so the outside seems cooked but the inside remains moist and deliciously raw. Try making CHOW’s Cured Salmon.

14 Ginger Beer

Though most commercially available ginger beer is just soda pop with air forced into it, traditionally the drink was naturally carbonated by allowing ginger, sugar, and water to ferment. Try making CHOW’s Ginger Beer.

15 Miso

A mold called Aspergillus oryzae is mixed with rice, barley, or soybeans, then aged in wooden casks for a few months to make this Japanese flavoring paste. Tamari and soy sauce or shoyu are made the same way, but in the case of shoyu wheat is also used.

16 Tempeh

Originally created in Indonesia, this bean cake is made by cooking soybeans and inoculating them with Rhizopus mold. The white mold binds the beans together.

17 Natto

A stringy, slimy soybean product from Japan often eaten over rice. Cooked beans are fermented with the bacterium Bacillus subtilis natto for a day, then aged under refrigeration for a few days more.

18 Marmite

A savory brown spread from Britain often eaten on bread, made from brewer’s yeast that is the byproduct of brewing beer.

19 Rumptof

A traditional German Christmas condiment. Fruit is marinated with sugar and rum in an earthenware crock.

20 1,000-Year-Old Egg, a.k.a. 100-Year-Old Egg, a.k.a. Century Egg

A Chinese delicacy. A duck egg is treated with quicklime, salt, and tea and then aged, oftentimes after being coated in clay-rich mud and rice husks for a month (not actually 100 or 1,000 years). The egg’s yolk turns gelatinous and greenish, and the white becomes amber-colored. The egg is often served cut up over porridge.

21 Kumiss

A traditional, mildly alcoholic drink from Central Asia made from fermented horse’s milk. It was not well loved by a CHOW writer in Mongolia.

22 Kombucha

A fermented beverage originally hailing from Asia, made from a symbiotic colony of yeasts and bacteria that are fed sweetened tea. The resulting elixir is slightly carbonated and, though unproven, is said to contain many health benefits.

23 Kvas

A popular Russian drink made from fermented rye bread. It’s lightly carbonated, with negligible alcohol content, and is sometimes flavored with fruit.

24 Rejuvelac

A naturally carbonated health tonic promoted by many raw-foodists, made from soaking wheat or rye berries and draining off the resulting liquid, which is loaded with enzymes.

More on fermented foods:
Tips on adding fermented foods to your diet










Fermented Fish




1,000-Year-Old Egg


Lessley Anderson is a former editor at CHOW.

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