Fermentation is a tried-and-true way to preserve and transform food with the help of billions of microbes. These tiny life forms include bacteria, yeasts and other fungi, and even molds.

Simply going about their lives, microbes consume the food’s energy source and along the way create many byproducts such as vitamins, enzymes, and short-chain fatty acids—which are nutrients to us! Fermented foods are also a rich source of probiotics, the living microbes themselves.

When we consume fermented foods, we get the benefit of all these nutrients. Probiotics support our gut microbiome, the collection of trillions of microbes found throughout our digestive system.

By consuming just a small amount of fermented foods or beverages (four to eight ounces of fermented veggies per day, or one to two fistfuls), we enjoy the many benefits fermented foods have to offer.

It’s Fine Under the Brine!

Sometimes when fermenting vegetables such as sauerkraut, layers of yeasts, molds, or both can form on the top surface that’s exposed to air. Fear not! You can simply wipe, scrape, and scoop off that top layer. As long as the contents are submerged under the salty brine mixture, they are safe to consume. As always, trust your senses when deciding if anything, fermented or not, is going to be good for your body.

Major Styles of Fermented Foods

Wild ferments are so-called because the microbes responsible for the fermentation process are found in the natural environment. In the case of foods such as pickles, sauerkraut, or kimchi, they get their microbes right from the cucumbers, cabbages, or other vegetables used in the recipe—no additional microbes need to be added to begin the fermentation. The bacteria responsible for this style of fermentation are part of a healthy plant’s microbiome, the ecosystem of tiny organisms that completely cover its leaves, stems, roots, flowers, and fruits.

Cultured ferments such as yogurt, kefir, miso, and kombucha didn’t get their name because they went to finishing school. These ferments won’t spontaneously start without a little microbial kick-start; we add a culture of a specific set of microbes we know will do the job of fermentation. To make yogurt, for example, we need to add a little bit of finished yogurt to fresh milk to start the process. It’s the same with kombucha: Sweetened tea needs the microbes present in the mother culture (a.k.a. the SCOBY) to begin the microbial dance of the bacteria and the yeasts.

Transformed foods such as chocolate, wine, or sourdough bread use fermentation in order to process, create new flavors and compounds, or otherwise enhance the raw food. However, they are further processed (usually through roasting or baking, or the creation of alcohol), which destroys any probiotic or living microbial content. The legacy of additional flavors, improved textures, and enhanced nutrients remains intact, though. For example, native bacteria and yeasts present in jungles where the cacao tree (Theobroma cacao) grows ferment the seeds into what we know as chocolate. Sourdough bread is given its sour flavor and airiness through fermentation by bacteria and yeasts from the starter culture, but when baked at high temperatures, those microbes do not survive the transition from dough to bread.


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Originally published in issue 72.

Cover photo: Becka Vance for Edible San Diego.
About the Contributor
Austin Durant
Austin Durant has been fermenting food for over 12 years. In 2011, he founded Fermenters Club, whose mission is to teach people why and how to make fermented foods at home, and to create communities connected through our guts. Austin teaches hands-on classes throughout San Diego County on fermented food traditions such as sauerkraut, pickles, kimchi, sourdough, kombucha, miso, and seasonal specialties. He is writing his first book, Fearless Fermenting, available in spring 2024!