Fermentation 101: The Fundamentals

Fermented foods and beverages are only getting more popular with consumers. By 2032, the global market is even expected to reach $989 billion! Why all the buzz? 

It’s common to hear fermented foods praised for their health benefits, from supporting gut health to mental health, as well as for their unique flavor profiles. And while fermentation has been a practice for centuries, today, these products are easier to find than ever. You’ll see kombucha on tap in bars, sourdough bread loaves piled high in local cafes, and more varieties of yogurt and sauerkraut than you can count in the grocery store.

Interest in fermentation as a natural, tasty health aide is clear. But let’s take a step back and return to the basics: what are fermented foods, and what benefits do they offer exactly? 

First things first. What is fermentation?

To put it simply, fermentation is a metabolic process that takes place in a mostly anaerobic (or oxygen-less) environment. During fermentation, an army of yeast and bacteria convert sugars and starches into natural preservatives like organic acids and ethanol (or alcohol). 

What you’re left with are foods and drinks with longer shelf lives and, according to some studies, enhanced nutritional value. The fermentation process also inevitably changes the flavor of foods, giving them a stronger, tangier, and more sour taste. That’s why some of our fermented favorites, like beer, yogurt, sauerkraut, sourdough, pickles, and kombucha, all have sharp, distinctive flavors — it’s a result of the organic chemistry behind fermentation. 

Although fermentation is often talked about as one method, in actuality, there are multiple types of fermentation. Let’s do a quick review of the three most common types:

Lactic Acid Fermentation: Also known as lacto-fermentation, this type of fermentation is used to make many common foods, from sourdough, sauerkraut, and kimchi to dairy products like yogurt and some cheeses. Many of its health benefits come down to the presence of specific lactic acid bacterias (LABs) that function as prebiotics and probiotics. While more clinical trials are needed, so far, research into these healthful bacterial strains is promising — one study showed that LABs help inhibit colon cancer, and others have indicated they reduce the risk of cardiovascular disease and Type 2 diabetes.

Alcoholic Fermentation: Alcoholic fermentation occurs when microorganisms convert carbohydrates to alcohol and carbon dioxide. This process relies mostly on the growth of [Saccharomyces] yeasts, and it’s how we get beverages like kombucha, wine, beer, and spirits. For many alcohol-fermented products, good bacteria and yeasts get removed during the production process, reducing the overall health benefits. Not so for kombucha (which, to be sold as non-alcoholic in U.S. stores, must have an ABV of <0.5%). Probiotic types and amounts can vary across kombucha brands, and it’s generally agreed more research is needed. But initial studies have positively linked kombucha to a number of health benefits, from a more diverse gut microbiome to improved liver health and skin health. 

Acetic Fermentation: This type of fermentation takes place when alcohol is exposed to air and is converted into acetic acid. We all know it as vinegar, which gives drinks like water kefir and kombucha their trademark tangy-sour taste. This fermentation type comes with its own set of health benefits, too, from its antibacterial properties to its use as a blood pressure regulator, antioxidant source, and protectant against cardiovascular diseases.

Because kombucha is the creation of not just one, but two beneficial fermentation processes, we like to think of it as an extra-magical fermented beverage. What do we mean by that? 

The magic of kombucha fermentation

We know we’re biased. But since kombucha is our favorite fermented food, we wanted to touch on its fermentation process and history in more detail. 

While its fizzy personality and flavor is a big part of the reason why consumers love kombucha so much, the science behind how it’s fermented is a close second. As we mentioned earlier, kombucha is fermented in a two-stage fermentation process. It’s unique because kombucha uses a starter culture known as a SCOBY (or, a Symbiotic Culture Of Bacteria and Yeast) combined with sweet tea to kickstart these two processes.

During fermentation, the SCOBY hydrolyzes kombucha’s sugar into fructose and glucose, which are metabolized into alcohol (for alcoholic fermentation). The SCOBY then oxidizes that alcohol, producing organic acids like acetic acid (for acetic fermentation) and contributing to kombucha’s trademark tart taste. Throughout both of these processes, beneficial yeast and bacteria feast and multiply. And there you have it — kombucha!

Back to the beginning: The history of fermentation

Stretching as far back as human history, the beginnings of fermentation are a bit tricky to track down. However, historians have discovered traces of fermentation in foods and beverages as far back as 8,000 BC. Since then, nearly every civilization in history has incorporated at least one fermented food into its culinary heritage — from Korean kimchi and Indian chutneys to sauerkraut, yogurt, and cheeses. It’s even a well-documented part of select Chinese empires’ practices with grain-based beverages like rice wine. 

So while humans in different cultures across the globe have enjoyed delicious fermented foods for centuries, it wasn’t until the mid-1800s that people started to understand the reason why their food was fermenting. We owe this discovery to French chemist Louis Pasteur who connected yeast to the process of fermentation. This crowned him as the first zymologist (someone who studies the science of fermentation.)

Now, fast forward 200 years to the modern era, and we’ve learned so much more about fermentation. And the amazing thing is: there’s still so much more to learn.

So, why should we care about the fermentation process?

Increasingly, research is telling us fermentation comes with some sizable health benefits. In particular, a still-growing body of studies suggest probiotics found in fermented foods and drinks, like kombucha, have a direct relationship to warding off disease-causing microorganisms, supporting our immune systems, managing inflammation, and aiding digestion and nutrient absorption. And as kombucha lovers, we sure can’t complain about the flavor it adds to our lives either!

Clearly, we could go on and on about the purpose of fermentation and the value it brings us daily. But we’re going to spare you from a potentially lengthy saga and keep it to four key takeaways to remember: 

4 reasons fermentation matters today: 

1. Fermentation can help break down hard-to-digest nutrients, making some nutrients more bioavailable, meaning our bodies can utilize them more effectively. 

2. Fermentation has the superpower of preserving food. Today we have the luxury of refrigeration, but long before this invention was even a thought, fermentation was crucial to survival during long winters or food scarcity. 

3. Fermentation boosts the amount of beneficial bacteria and other live microorganisms (or probiotics) found in foods and beverages. And probiotics, in turn, have been tied to improved digestive and mental health, largely thanks to their role in promoting gut flora diversity. 

Scientists are better understanding the relationship between gut flora, mood, and cognition — there’s a reason the gut is called the “second brain,” after all! The gut’s enteric nervous system, or ENS, is in constant communication with the body’s central nervous system, which may be why poor gut health is increasingly being linked to mood changes, depression, and anxiety. Conversely, good gut bacteria is thought to improve the mood and even help us make better decisions. Not only that, but the feel-good neurotransmitter serotonin is actually produced in the gut. Pretty amazing, right? 

Ultimately, research on probiotics — and the probiotic value of specific foods and beverages — is still ongoing. But particularly when compared to probiotic supplements, many doctors and academics see value in naturally adding depth to your diet with fermented foods. 

4. Research shows our collective gut flora diversity — and, therefore, our gut health — is in decline compared to past generations. And one of the best ways to get more healthful bacteria in our guts is by eating fermented foods. 

Just consider a recent clinical trial from Stanford University. Among participants assigned a 10-week diet high in kombucha and other fermented foods, Stanford researchers saw improved gut microbial diversity, lowered immune cell stress, and fewer inflammatory proteins, including a protein linked to rheumatoid arthritis, chronic stress, and Type 2 diabetes. 

The bottom line? Beneficial, diverse bacteria helps gut health, which is essential to whole-body health. Eating and drinking delicious, nutrient-dense fermented products, like kombucha, is one way we can invest in our guts and ourselves.