Fermentation for beginners: learning the basics + recipe

On beneficial decay processes and healthy bacteria

Fermented products. Without a doubt, not a day goes by without you eating and drinking at least one fermented product. Think sauerkraut, desiccated bread, beer, coffee, wine, yogurt, cheese (yes, including many vegan varieties), soy sauce, vanilla, and even chocolate.

But what exactly is fermentation? And can you do it yourself? The answer to the second question is a resounding yes, so let’s take a closer look at the process of letting a product rot in a controlled manner.

What is fermentation?

One of the best-known fermented products is undoubtedly sauerkraut (recipe below). You may not realize it when you buy it wrapped in plastic at the supermarket or straight from the barrel at a traditional greengrocer (where do you find those anymore). Still, sauerkraut is nothing but “rotted” white cabbage (or any other cabbage, but white cabbage is the best known and works best).

And that is the shortest definition of fermentation: the controlled rotting of vegetables, fruits, coffee beans, or whatever. That controlled rotting is done with the help of microorganisms such as bacteria, fungi, and yeasts that are usually already present in or on the product to be fermented or that are added to it.

These microorganisms break down molecules and transform them into something else, changing the product’s taste. For example, with the help of some salt as a catalyst, white cabbage transforms into sauerkraut as the lactic acid bacteria in the cabbage are converted to lactic acid. And so, with the help of brewer’s yeast, barley juice ferments into a mixture in which ethanol (alcohol) and carbon dioxide play a significant role and has been making waves as beer for centuries.

Lactic acid bacteria

To reassure all vegans once and for all: those lactic acid bacteria have nothing to do with animal milk products in nature, although they also play a major role in converting milk into buttermilk or yogurt. For example, they are abundant in the human body and are indispensable in the intestines in breaking down bad bacteria.

In women, lactic acid bacteria in the vaginal flora form an important line of defense to keep out possible pathogens. And anyone who overexerts themselves during a round of gymnastics will also encounter lactic acid bacteria. Glucose is the fuel for muscles. When muscles are in motion, glucose is broken down, and in the process, lactic acid bacteria convert it into lactic acid. So if you go on too long, your muscles literally acidify.

Good for your health?

Because the fermentation process uses many microorganisms that are also present in our bodies, fermented foods are certainly not bad for us. There are even voices in science that claim that fermented fruits and vegetables are often better for us than fresh raw fruits and vegetables. This is because of the pesticides that, unfortunately, are still present on many foods even after proper washing.

The fermentation process breaks down these toxins and, where possible, converts them into good bacteria called probiotics. It also preserves many substances and vitamins necessary to the human body.

It was discovered in ancient times that on sailing ships where sauerkraut was a regular part of the menu, there was much less scurvy among the crew than on ships where it was not. The reason is simple: the lactic acid in sauerkraut preserves the vitamin C present in the cabbage. And it is precisely the lack of vitamin C that was the main cause of scurvy. 

In fact, by now it is already believed that fermented foods are beneficial for mental health and promote processes such as faster learning, clear thinking, and problem-solving. 

Why ferment?

The preservation of food and the vitamins and other bioactive substances it contains has traditionally been the main reason for fermenting vegetables and other products. By converting sugars into lactic, alcohol, or acetic acid, a product will keep much longer even without refrigeration.

In addition, fermentation often changes and improves the taste, texture, and digestibility of vegetables and creates a tremendous source of healthy live bacteria.  

A little history

Although the science behind fermentation and probiotics is still relatively young, the process has been known for millennia. Traces of risen bread have been found that are more than 10,000 years old. And that bread rose through a form of fermentation.

ferment sourdough bread

Forms of yogurt are also known from the period between 10,000 and 5,000 years before Christ. For example, cattle herders in the Middle East at that time kept milk in goatskin bags. The burning sun did its job and caused the milk to ferment through the combination of heat, lactic acid bacteria present, and fermentation. The result: kefir.

And since the Middle Ages, the value of fermented liquids such as beer and wine has been very clear: it was safer to drink beer than water. With the reassuring note that the alcohol content of the beer consumed on a daily basis was then a lot lower than that of today’s pilsner.


Yet it was not until the middle of the nineteenth century that scientists also began to take fermentation processes seriously. In 1857, Louis Pasteur published his Mémoire sur la fermentation appelée lactique. And it was only around 1908 that Elie Metchnikoff touched on the beneficial effects of lactic acid bacteria in his book The Prolongation of Life.

We had to wait until 1953 for the term probiotics. Meanwhile, the beneficial effects of fermentation are being widely researched worldwide, and more than three thousand studies are charting the power of sour pickles, sauerkraut, salted beans, beer, chutney, wine, soy sauce, tempeh, and whatnot.

Different Fermentation Processes

With such a rich variety of products comes a diversity of fermentation processes. Because there is no one way to ferment. The best known is the fermentation with lactic acid bacteria, the fermentation that leads to sauerkraut, but also to what they so beautifully call pickles in England. In addition, the lactic acid bacteria play a role in the creation of desiccated bread, (natural) wine, beer, tabasco and so on that are less interesting for vegans. 

fermentation pickle

Then there is the power of yeast which converts sugar into alcohol and carbon dioxide and plays a role in again beer, wine and bread. And then there is a form of fermentation by fungi. In Europe, the role of molds is limited to the production of blue cheese and natural crust cheeses, but true masters of mold live in Asia. Miso, tempeh, rice wine, soy sauce, to name a few, all involve a fungal-based fermentation process. It is certainly not the easiest form of fermentation, but it is an enormously flavorful one.

A final form of fermentation continues after the creation of alcohol. The addition of certain fungi and under the influence of oxygen creates acetic acid, the basis of vinegar, for example. Although the controlled exposure to oxygen makes it a tricky process, the basics are simple in this case as well. Leave a good bottle of wine open and in contact with oxygen for a few days, and you will know what this process entails….

The difference between fermentation and pickling

Although you can transform small cucumbers into delicious pickles through both fermentation and pickling, there is a fundamental difference between the two methods.

Pickling vegetables is a fairly quick process where you use vinegar and flavorings including added sweeteners, to balance the sweet and sour content. You add acid.

In fermentation, microorganisms break down the sugars, creating the acid. In fact, fermentation is not only a longer-lasting process but also a more natural one. 

Fermenting yourself

Fermenting products yourself is a challenging process. Especially the idea that you are dealing with controlled “rotting” of a product can make you unsure of the final outcome. My first experiments to make a good sourdough were an absolute disaster. Most of all, they taught me what can go wrong and what is of great importance.

The right proportions, the right room temperature, and regular feeding of the sourdough starter are of vital importance. Fortunately, in this respect, your own nose is the most important gauge. If you don’t trust it because your dough or vegetables don’t smell fresh (and I mean sour) anymore, leave the ultimate judgment to your olfactory system. This one, unless you venture into wild Asian-inspired experiments, is always right.

And above all, don’t be afraid of a few failures here and there. After all, each failure teaches you more about the process of fermentation, and it really does pay off in the end. 


The easiest thing to start with as a beginner fermenter is vegetables. For example, make a jar of pickles from leftover vegetables such as cauliflower, carrot, and cucumber. Take 500 grams of vegetables (in large pieces or cut into smaller slices), mix it well with 15 grams of salt (and possibly some other herbs to taste), put it in a jar that can be sealed with as little oxygen as possible, add water until the vegetables are submerged and seal the jar. Leave it at room temperature for a few days to two weeks and let the process do its work.

Vegetables cut into small pieces are often ready after about four days. Larger pieces require a little longer. After this fermentation period, the vegetable tastes deliciously slightly sour and can be kept in the refrigerator forever. 

Recipe Sauerkraut

You can make fermentation as easy or difficult as you want. Of course, you can specialize like crazy and buy all kinds of expensive tools. Still, to make sauerkraut, for example, you don’t need much more than a mixing bowl and a sealable vessel large enough to accommodate the amount you’re making.

making sauerkraut

To demonstrate simplicity, here’s a quick recipe for delicious basic sauerkraut.

Take a kilo of white cabbage with the hard core removed and cut it into very thin strands (I’m of the self-cutting variety with a razor-sharp knife, but a mandolin works great too).

Add at least 15 grams of salt per kilo (if you want more spice and salt in the flavor go up to 25 grams).

Bruise the cabbage until it begins to turn glassy and loses moisture. Let it rest for a while, and then once again vent your pent-up aggression on the poor cabbage.

Add any other spices such as mustard seed, peppercorns, juniper, bay leaf and whatever else your taste fantasy approves of. Toss everything into a weck jar, sauerkraut jar, or sealable bucket.

Cover the sauerkraut with a large cabbage leaf, possibly placing something weighty on top to make sure the cabbage is under the moisture and has as little contact with oxygen as possible, and seal the jar or bucket.

Set aside at room temperature and once every two days, flip open the lid to allow the gases formed to escape. After a week or two, the cabbage has transformed into sauerkraut, and you can place the jar or bucket in the refrigerator to stop the fermentation process.

This homemade sauerkraut will keep in the refrigerator for at least a year, although I must confess that a barrel of sauerkraut has never made it that long on my watch; it is just too delicious both in the familiar stew and prepared differently.

For example, try a dish I learned about thanks to a pianist friend from Ukraine: vareniki. Pasta dough (obviously just made without egg, from water, a little salt, and the finest possible flour) filled with braised sauerkraut and fried onion served with some dill and vegan crème fraise. It may sound crazy, but the taste is absolutely surprising and addictive especially with homemade sauerkraut.

Further experimentation

If you’ve got a taste for fermentation and want to not only make sauerkraut, pickles, and your own sourdough bread but also enjoy your own fermented salted beans, tempeh, soy sauce, wine (I can’t wait for the blackberry bush to be full of blackberries again …), beer, vegan cheese, ditto yogurt, and whatnot, then dive into the literature that is generously available.

Have you ever fermented vegetables or fruits? Do you feel like getting started after reading this article? If so, be sure to leave a comment at the bottom of this page.

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