What’s Brewing with These Fermentation Terms?

Terminology used in preserving and fermentation can be very confusing and is often misused.  Thank goodness, help has arrived! Published by Phickle in September 10, 2014 by Amanda, this is the best guide for getting these things sorted out.  Here’s the full article:

Sometimes, when reading on the internet, I’ll see some stuff about how kombucha is such a delicious lactofermented beverage, or how it was amazing to find out the even chocolate and vinegar are lactofermented (or worse “probiotic.” They’re not.)! Those things are all fermented, of course, but they are not lactofermented. I totally understand the confusion, so I thought I would offer a little cheat sheet on which common fermented food goes with which type of fermentation.

Yogurt is a lactic acid ferment

Yogurt is a lactic acid ferment

Lactic Acid Fermentation

Lactic acid fermentation is so called because of its lactic acid bacteria. These bacteria are call lactic acid bacteria (LAB) because they produce lactic acid (shocker) and not because they have any milk or dairy products in them. Lactic acid bacteria are present in the soil, and therefore on the things that grow in the earth. There are also strains of lactic acid bacteria naturally present in dairy milk. Lactofermented foods are the foods that can be called “probiotic” based on their production of health-enhancing bacteria.

Sauerkraut doesn't need any dairy or whey! Cabbage is naturally covered in lactic acid bacteria.

Sauerkraut doesn’t need any dairy or whey! Cabbage is naturally covered in lactic acid bacteria.

Some Favorite Foods Made Through Lactic Acid Fermentation (lactofermentation):

  • Sauerkraut
  • Kimchi
  • Pickles, including cucumber pickles and all pickled vegetables (these can also be canned, not a fermentation process)
  • Yogurt
  • Cheese (some cheeses are further fermented with molds, see below)

Yeast Fermentation

When we talk about yeast fermentation, we’re talking about the metabolic activity (think: eating) of yeast on sugars. When yeast eat sugar, they create waste products, most specifically CO2 and alcohol (ethanol). The CO2 makes things bubble. The ethanol makes you drunk.

Homemade sourdough bread uses wild yeast and bacteria to become some delicious. Other bread will rely solely on the rising power of yeast.

Homemade sourdough bread uses wild yeast and bacteria to become some delicious. Store bought yeasts are usually isolated yeast strains.

Some favorite foods made through yeast fermentation:

  • Beer
  • Wine
  • Bread (sourdough bread is a mixed ferment that involves both yeast and lactic acid bacteria. It’s not probiotic, though, because the bread is baked at a temperature that kills the good bacteria).

Acetic Fermentation

Vinegar is not lactofermentation

Acetic fermentation is pretty crazy, because the bacteria responsible for this kind of fermentation live in the air and make their way in the world as booze-hounds. Acetobacter, the genus of bacteria that readily make acetic acid from alcohol,  consume the ethanol in wine, cider, beer, etc and make it into tasty vinegar. They require air to do their work, which is kind of an odd thing about them in the fermentation world (the biological definition of fermentation usually contains the word “anaerobic” (airless).) That’s why when you’re making booze or wine, you definitely want an airlock in the mix. If acetobacter in the air get in there, they’ll turn your lovely wine into (possibly also lovely) vinegar.

Some favorite foods made through acetic fermentation:

  • Wine Vinegar
  • Malt Vinegar
  • Apple Cider Vinegar (or other fruit vinegars)

Bacteria/Yeast/Mixed Ferments

Milk Kefir Grains

Milk kefir grains combine the power of yeast and bacteria.

SCOBYs are physical cultures that combine the fermentation powers of both yeast and bacteria as their name, an acronym that describes that relationship (Symbiotic Community of Bacteria and Yeast), suggests. These guys typically work together to create their physical structure, a matrix of cellulose. In the case of the kombucha SCOBY, for instance, these microbes work together in interesting ways. The yeast consume the sugars in the tea drink and produce waste products which are in turn consumed by the bacteria and used to create more SCOBY and tasty kombucha.

Some favorite foods made through symbiotic fermentation*:

  • Kefir
  • Water Kefir
  • Kombucha
  • Ginger Beer Plant
  • Sourdough Bread
  • Ginger Bug (with all the added sugar, this one likely veers more into yeast ferment territory, but I’ve definitely made a few ginger beers with some lactic bite)

Mold Ferments

Cow's milk cheese made in New Jersey

Not all cheese is made with mold, but lots of lovely ones are.

Other than cheese there aren’t a whole lot of moldy things or mold-fermented things that we Americans eat on the regular. There are some truly delightful and traditional ferments hailing from Asia that fall into this category. They can be a little trickier to ferment, and may require more patience or equipment (or at least spores), but they are often worth the elbow grease!

Some favorite foods made through mold fermentation*:

  • Tempeh
  • Koji (which makes miso, sake, amazake and soy sauce)
  • Some cheeses

*That is not an actual term, nor is it a true “type” of fermentation. It’s two different types of fermentation happening in the same food/drink. There are plenty of ferments that have multiple kinds of fermentation happening at different times, or even overlapping. This isn’t intended to be a full, scientific accounting, but rather a little overview that laymen can use to talk or write about their ferments.