Fermentation might sound like something that belongs in a modern food lab.
But in reality, it is one of nature’s oldest ways of giving raw ingredients flavour, texture, and an extended shelf life. Fermentation is what turns milk into cheese, cabbage into kimchi, and grain into beer.
In this article, we’ll take a closer look at what fermentation actually is, which foods can be fermented, and how bacteria, yeast, and fungi can create more flavour, entirely new textures and improved shelf life in a wide range of ingredients.
What is fermentation?
Rye bread, cheese, beer, and kimchi are all very different foods, yet they still have something in common. They are all fermented foods.
Fermentation is what happens when microorganisms such as bacteria, yeast, or fungi break down carbohydrates and proteins, and transform them into something new.
Milk becomes cheese, cabbage becomes kimchi, and grain becomes beer. Although it may sound like something invented in a laboratory, the reality is actually quite the opposite.
It is, in fact, just natural biology that has existed and shaped food for thousands of years.
The word “fermentation” simply refers to this same process, and “fermented” describes the result: a raw ingredient that has undergone fermentation.
What are fermented foods: You may already know most of them
Most people are familiar with more fermented foods than they might realize.
Yogurt, sourdough bread, cheese, kimchi, kombucha, miso, beer, and wine are all examples of fermented foods. Many of them are even a regular part of everyday cooking in a typical Danish kitchen.
For that reason, fermented foods are neither niche nor exotic health products from your local deli. It is simply just the bread we spread butter on in the morning, and the cheese we put on top.
Since all these ingredients have undergone a fermentation process, they typically end up with more flavour, improved shelf life, or a completely different texture compared to their original form. Whether we’re talking about a classic Danish cheese or Korean kimchi, ultimately the same biological process is involved.
Today, fermentation is also used in modern plant-based food. Not as a way of mimicking meat with protein isolates and flavourings, but as a method of creating flavour and texture in a more natural way, without heavy processing.
What happens to the body when we eat fermented foods?
Fermented foods are not just a culinary experience. The fermentation process actually changes the chemical composition of food in ways that appear to benefit the body in several respects.
One of the most well-documented effects concerns anti-nutrients. Many plant-based foods naturally contain phytic acid, which can bind minerals such as iron, zinc, and magnesium. This makes it more difficult for the body to absorb these minerals.
However, according to research, phytic acid is naturally broken down during fermentation. Studies also suggest that the bioavailability of these nutrients increases due to the breakdown of phytic acid.
In addition, fermented foods contain live microorganisms. Several studies also indicate a link between regular consumption of these and a more diverse gut microbiota.
Are oats, rye bread and yoghurt fermented?
It depends a great deal. And that is precisely what makes the question worth asking.
Yoghurt and skyr are fermented. They contain lactic acid bacteria, which are active and go through the same classic fermentation process.
The same applies to sourdough bread. The sourdough live culture, also known as lactic acid bacteria, works with both flour and water before the bread is baked.
On the other hand, rye bread is more nuanced. If it is left to rise like sourdough, it is fermented. However, if it is leavened with yeast alone, without an active sourdough culture, the same breakdown of anti-nutrients does not occur to the same extent. This is the case whether it is baked in an artisan bakery or a factory.
As for oats, they are not fermented themselves. However, you can ferment oats by soaking the flakes overnight with a little acid. This initiates a similar fermentation process.
How do you ferment vegetables at home?
It is actually easier than you might think. And you probably already have everything you need for a good result.
All you need for lacto-fermentation is vegetables, salt, time, and an anaerobic environment (a place without oxygen). This could be a clean jar that can be sealed.
You will need:
- Fresh vegetables such as cabbage, carrots or beetroot
- Salt
- Water
- A clean jar with a lid
- Optional spices such as garlic, chilli, dill, ginger or peppercorns
As a general rule, you can make a salt water solution (brine) using 20 grams of salt per 1 litre of water.
How to do it:
- Prepare the vegetables: Wash the vegetables thoroughly and cut them into the shape you prefer. Cabbage can be finely shredded, while carrots and beetroot work well as sticks, slices or cubes.
- Put the vegetables into a clean jar: Place the vegetables tightly into the jar. The tighter they are stacked, the easier it is to keep them submerged in the brine.
- Add the brine: Stir the salt into the water until it is fully dissolved. Then pour the brine over the vegetables so they are completely covered by the liquid.
- Keep the vegetables submerged: It is important that the vegetables do not rise above the liquid. You can use a small clean jar or a cabbage leaf to weigh them down.
- Leave the jar at room temperature: Leave it on the kitchen counter for a few days. If the jar is tightly sealed, it is a good idea to briefly open the lid once a day to release any built-up pressure.
- Taste as you go: Carrots and beetroot are often ready after 3 to 7 days. Depending on how tangy you want the flavour, cabbage can usually be left a little longer.
- Refrigerate: Once the vegetables have reached your preferred flavour, place the jar in the fridge. The cold slows down fermentation, which helps the vegetables stay crisp and fresh for longer.
When fermenting vegetables, you make use of the natural lactic acid bacteria found on the surface of most vegetables. When the vegetables are placed in salt, the bacteria begin converting the sugars in the vegetables into lactic acid.
It is this lactic acid that gives the fresh, tangy flavour and helps preserve the vegetables.
Which vegetables can you ferment?
You can ferment many different vegetables, especially those with a firm texture and a natural content of sugar. Cabbage, carrots, beetroot, cucumbers, cauliflower, radishes, onions, peppers and chillies are all good examples of vegetables that are easy to ferment at home.
- Cabbage is a classic to begin with. When finely shredded, massaged with salt and placed tightly into a jar, it becomes sauerkraut. If you add ingredients such as chilli, garlic and ginger, it moves closer to something like kimchi.
- Carrots and beetroot also work well: Carrots and beetroot keep their crunch during fermentation. Cut them into sticks, slices or cubes, place them in a clean jar, cover them with brine, and leave them to ferment at room temperature for a few days.
- Cucumbers, radishes and cauliflower: These vegetables can also be fermented. They can be left whole, sliced or broken into small florets, depending on the vegetable. Here it is especially important that they remain fully covered in brine so that the fermentation process proceeds as it should.
As a general rule, firm vegetables are best suited. Softer vegetables can also be fermented, but they often lose their structure and become even softer in texture during the process.
Ultimately, the basic principle is always the same. The vegetables should be clean, covered in brine, and given time to develop flavour.
Everything else comes down to variation.
What about fermented meat?
Just like vegetables, meat can also be fermented. This includes products such as salami, cured sausage and other dried sausages, all of which are fermented foods.
In these products, fermentation occurs when bacteria acidify the meat, which both develops flavour and extends their shelf life. This is why these types of sausages have a characteristic slightly tangy and deep flavour.
The same biological process can be applied to plant-based variations. Instead of bacteria, MATR uses fungal mycelium to ferment a blend of oats, split peas, lupins, beetroot and potatoes.
The result is texture, tenderness and an umami-flavour, made without meat and without a long ingredient list.
Fermentation with fungi: What actually happens?
Fungi also ferment, but they do so in a different way from vegetables and meat.
When fungal mycelium grows into a raw material, it sends out thousands of tiny root-like structures called hyphae throughout it. The hyphae break down nutrients from within, and release flavourful amino acids in the process.
This is the same process that gives aged cheese and miso their deep, rounded flavour, just with fungi instead of bacteria.
This is the exact process MATR uses, when we are developing our fermented products. When oats, split peas, lupins, beetroot and potatoes are fermented with a fungal culture, the result is a firm and tender plant-based product with a deep, rich flavour.
Here, the fungal culture binds the raw materials together, creating a texture that can be used for plant-based burgers, mince or other meat alternatives. There is also no need to add additives to create flavour.
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