Fermentation is an umbrella term for certain conversion processes of organic substances with the help of microorganisms or enzymes. In the food industry, fermentation is used, for example, to preserve and produce, natto, tofu, miso, soy sauce, kimchi and cheese or to refine tea, coffee and cocoa. Both the alcoholic fermentation of beer, wine or whiskey and the lactic acid fermentation of buttermilk or kefir are referred to as fermentation processes.
While the fermentation of tea is mostly based on enzyme reactions of the leaf enzymes, various microorganisms are responsible for the fermentation of sauerkraut, miso, natto or kefir. Since these microorganisms are in the air, on vegetables or in water, almost any vegetable can be fermented to create a probiotic food. But what exactly happens during fermentation?
Fermentation can be explained quite well using the production of sauerkraut. To make sauerkraut, fresh white cabbage is first cut into fine strips. The white cabbage already contains natural lactic acid bacteria, which also live in our intestines. The white cabbage is mixed with a lot of salt and mashed with a cabbage masher so that the cell juice escapes. On the one hand, the salt causes the cabbage to release water and, on the other hand, it also preserves it until the start of lactic acid fermentation.
Together with the salt, the cell sap forms the so-called brine. The herb must be pounded and pressed until it is completely covered by the brine. This creates an oxygen-free environment around the herb, which makes lactic acid fermentation possible in the first place.
Under anaerobic conditions (without oxygen), the lactic acid bacteria begin to convert the sugar contained in white cabbage into lactic acid. Through this reaction, the bacteria create an acidic environment in which only they can thrive and harmful putrefactive bacteria have no place.
Depending on the temperature, the fermentation time is between three and six weeks – the warmer, the faster the fermentation takes place and the longer the herb is left to ferment, the more intense the taste.
On the one hand, raw, fermented sauerkraut still contains a lot of vitamins and minerals and, on the other hand, the valuable lactic acid bacteria, which were able to multiply nicely during the fermentation. These lactic acid bacteria are also part of our gut flora, so fermented vegetables like sauerkraut are great probiotics and can help us make sauerkraut.
However, if you think that sauerkraut from the supermarket contains a lot of vitamins and probiotics, you will be disappointed. Traditional canned or jarred sauerkraut is most often pasteurized (heated) after fermentation, which destroys vitamins and probiotics. Unfortunately, most people nowadays only know cooked sauerkraut, although raw sauerkraut tastes at least as good with a little linseed oil, for example. You can either make raw sauerkraut yourself or buy it at the market.
The importance of probiotics for our health is enormous. The intestine and its intestinal flora play a crucial role in our overall well-being. The positive effects of probiotics start with better digestion and help with the absorption of nutrients.
Another major advantage of these beneficial, probiotic bacteria in the gastrointestinal tract is the suppression of harmful putrefactive bacteria, fungi and other parasites. An example of this is the yeast Candida albicans, which can infect our intestines.
However, Candida only becomes harmful when it is allowed to spread in excess, i.e. when there are not enough probiotic bacteria to keep it in check. A Candida infection is not only unpleasant but can also promote the spread of cancer cells and should therefore definitely be treated. Eating fermented vegetables can be very helpful in preventing Candida infection.
Probiotic bacteria are also needed for the immune system. It is estimated that the intestinal flora makes up about 60 to 80 percent of our immune system, because the intestinal bacteria not only kill putrefactive bacteria or fungi, but can apparently trigger immune responses throughout the body.
The small intestinal dwellers apparently even have an influence on our psyche. Only recently have links been found between low levels of probiotics in the gut and anxiety, depression, autism and many other mental conditions.
In addition to vitamins, minerals and probiotic lactic acid bacteria, fermented foods can also provide our body with valuable enzymes, as is the case, for example, with the Japanese food called natto.
Natto consists of fermented soybeans, which are not fermented by lactic acid bacteria, but by Bacillus subtilis natto. These microorganisms have a very health-promoting effect: They form a specific enzyme, the so-called nattokinase, which is able to break down deposits in our blood vessels. The great thing about nattokinase is that it doesn’t appear to be inactivated during digestion, but is actively available to us immediately after consumption.
For example, Bacillus subtilis natto lives on rice straw, so the soybeans used to make natto were originally wrapped in rice straw to start the fermentation process. Today, soybeans are usually inoculated with cultured bacteria to speed up the process.
Since natto has such a positive effect, but not everyone likes the harsh taste of fermented soybeans, you can now buy natto or the isolated nattokinase as a dietary supplement.
It is quite easy to ferment vegetables yourself and thus benefit from the positive properties of fermented food. Fermentation is particularly useful for preserving home-grown vegetables from your own garden because a particularly large number of natural microorganisms live on untreated organic vegetables.
For the fermentation, the desired vegetables (e.g. a small pumpkin or carrots, onions and cabbage ) are cut into fine pieces and mixed with any spices such as mustard seeds, caraway or fresh dill and 2 to 3 tablespoons of rock salt. By stirring and pounding, the cell juice escapes from the vegetables and the brine forms. If the brine is not enough to completely cover the vegetables, you can also add some high-quality spring water, which should not be contaminated with chlorine or fluoride, until the vegetables are completely covered.
For example, the vegetables are layered with the brine in a ceramic pot (never fill the container completely) and covered with a plate that fits exactly into the pot. The plate can be weighed down with a heavy water bottle, for example, so that the vegetables are well pressed together and the remaining air is pressed out.
Depending on taste, the fermentation batch should now stand at room temperature for at least a week so that the bacteria can do their work. The longer the vegetable is fermented, the more intense the flavour becomes.
To store the finished fermented vegetables, it is best to fill them in previously boiled jars, close them well and place them in the refrigerator or in the cold cellar. The fermented vegetables should keep for a few weeks or even months.
A little trick that will keep the vegetable firm during fermentation is to add washed grape leaves. Grape leaves contain something called tannins that help the vegetables stay crisp.
When it comes to fermenting vegetables, there are no limits to creativity. Try it out and enjoy your homemade probiotic foods.
With this kimchi recipe, we show you how you can ferment your vegetables into kimchi and thus preserve them.