What is Fermentation and How Does the Fermentation Process Really Work?


Fermentation is an ancient method of food preservation that utilizes beneficial bacteria and yeast to transform fresh produce into long lasting, probiotic-rich fermented foods and drinks that not only taste great, but also reduce overall food waste.

Before the invention of the modern refrigerator, people fermented their foods to preserve their harvests and to save any excess produce for the long winter months. For thousands of years, humans regularly consumed fermented foods. They evolved alongside and adapted to these beneficial bacterias. Today, there is a renewed interest in the science behind fermentation, specifically as it relates to potential health benefits to the human body (disease prevention, immunity support, gut health improvement and mood regulation – to name a few).

How exactly do you ferment food? Well, there are several ways that you can ferment fresh produce: Lacto-fermentation, wild heirloom fermentation, alcohol fermentation, acetic-acid fermentation, mold fermentation, and more! Let’s take a look at some of the big ones:

1. Lacto-Fermentation

Lacto-fermentation is a specific type of fermentation that uses lactic-acid-producing bacteria to preserve foods. Some lacto-fermentations, such as kimchi or sauerkraut, submerge fresh produce under a salty liquid (known as a brine) for a number of days or weeks until the fermentation process is complete. The salty brine provides the perfect place for good bacteria like lactobacillus (thus the name “lacto-fermentation”) and leuconostoc bacteria to thrive and produce lactic-acid, which is what preserves the foods. Examples of lacto-fermented foods include sauerkraut, kimchi, olives, cucumbers, fermented milks, yogurts, sourdough bread and other pickled vegetables.

Fermented Salsa

2. Wild Heirloom Culturing

While you can ferment just about any vegetable using the lacto-fermentation method, some root vegetables may be better fermented using a second method called “Wild Heirloom Culturing.” This term was coined by the great fermentation guru and microbiologist Kaitlynn Fenley. Here is how Kaitlynn explains the process:

“My wild Heirloom culturing method uses sauerkraut brine (or any fermented vegetable brine) and apple cider vinegar to ferment fresh vegetables using wild heirloom cultures found in the fermented sauerkraut brine. This method of fermentation is more similar to yogurt fermentation than it is to something like sauerkraut fermentation… and it’s very similar to refrigerator pickling (aka quick pickling), but with beneficial microbes included.”

Kaitlynn Fenley
Fermented Quick Pickled Carrots

3. Anaerobic vs. Aerobic Fermentations

Some fermentations need oxygen, some fermentations do not. When making kimchi or sauerkraut, for example, the salty brine used to submerge the vegetables in acts as a barrier against oxygen. These types of oxygen-free fermentations are known as anaerobic fermentations. Other fermentations rely on the presence of oxygen to complete fermentation, such as vinegar fermentation. These oxygen-loving fermentations are known as aerobic fermentations. It all depends on what you’re going for.

For example, wine must be bottled or contained in an oxygen-free environment or it runs the risk of “spoiling.” In this case, spoiling means turning from wine into vinegar. When wine is exposed to oxygen, certain organisms in the air we breathe – including acetobacter – enter the wine, start feeding off of the alcohol and metabolize the ethanol into acetic acid, the primary component of vinegar that gives it that distinct sour taste.

So, if you are trying to make a nice homemade red wine vinegar with your left over red wine, be my guest. Pop that cork and let it breath for a few weeks in a dark corner (cover with a cloth to prevent fruit flies). Soon you’ll have vinegar. But, if you want to preserve the wine as wine, better get a Coravin to keep the oxygen out.

4. Mold Fermentation

Say what? It’s true! Tempeh is a traditional fermented food made from soaked and cooked soybeans that are inoculated with a mold, usually of the genus Rhizopu.


5. Salt-Cured

Ok, so this isn’t exactly a fermentation method. However, salt-cured fruits, vegetables and even eggs(!) are still a wonderful and ancient way of preserving food and reducing food waste. Check out the Moroccan Salt Preserved Lemons recipe for inspiration.

Salt Preserved Lemons

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