Kraut fermentieren

What is lacto fermentation?

In German, lactic acid fermentation. The fermentation is started with the help of the yeasts that occur naturally on food. Liquid is removed from the food by means of salt, the yeasts are activated and begin to process the food. Salt ensures that the "good" valuable bacteria have the upper hand. The pH value of the food is thereby reduced. This makes it acidic and durable.

Pickled versus fermented? Pickle: pickled cucumber!  

Like fermented vegetables, vinegar-sour vegetables are a type of preservation. Vinegar itself is the product of a fermentation process. Juice becomes alcohol, becomes vinegar. However, if vegetables are pickled in vinegar, there is no bacterial activity. In short, pickled vegetables change taste, consistency and shelf life, but have no prebiotic effects.

How do I ferment vegetables? What is important here?

  • Use organic vegetables. Over-treated vegetables sometimes contain substances on their surface that prevent spontaneous fermentation.

  • Use salt without trickling aid, iodine and the addition of a separating agent - see also: Salt for fermentation

  • Make sure that the entire fermentation material is covered with brine, according to the motto "under the brine, it is fine"

  • Take a container that corresponds to the amount of your digestate. There should still be some space in the vessel, as the fermentation process will lead to a slight increase in volume, but the glass should not only be half full - see also: Fermentation vessel

  • Let your ferment start for a few days at room temperature. It should bubble and ferment properly. As soon as this process has subsided, you can put the fermentation material a little cooler for the final maturation.

  • Do not put your digestate in the refrigerator until the maturing process has ended. The low temperature reduces fermentation to a minimum.

  • Do not heat your vegetables over 40 degrees as this will kill the valuable bacteria.



Recipe & instructions

Sauerkraut, classic


  • 3L swing glass / fermentation pot

  • Planer / knife

  • big bowl


  • 3kg herb

  • 60g salt (not iodized, no separating agent)

  • Caraway seeds

  • juniper


Slice or finely chop the cabbage, leaving the stalk behind. Mix with the salt, caraway seeds & juniper. Let rest for 2 hours, the herb begins to cry.

In the meantime, rinse a swivel glass with hot water and let it cool down. Press the herb firmly into the glass, there should be no air chambers in the herb mixture. The brine should completely cover the herb. If not - mix 200ml water with 4g salt and pour in until all the herbs are under the brine. A large herb leaf and weight can help hold the herb under the brine.

Let the herb stand at room temperature for 1 week. Resist the temptation to keep opening the lid. Unwanted bacteria can enter. After a week, if possible, put your herb a little cooler - around 15-18 degrees. After 4 weeks you will taste your herb.


Tips & Tricks

Which vegetables can you ferment?

Pretty much every vegetable can be fermented. But you should observe a few basic rules.

Vegetables that contain water, such as cucumbers or tomatoes, become very soft over time and lose their texture. See also:  How do I keep my vegetables crunchy?

The harder a vegetable is to digest, the greater the benefit from fermentation.

Can you ferment fruit?

Yes, just keep in mind that salt is used for lacto fermentation. The salt serves to keep the correct bacterial balance. That means you get salty and sour fruit. Salted lemons, salted orange or salted plums (umeboshi) are examples of fermented fruit.

How do I keep my vegetables crunchy?

The addition of tannins preserves the texture of ferments. This can be done using leaves (vine leaves, fig leaves, cherry leaves) or by using a fermentation vessel with tannins (oak barrels).

How much salt is needed for fermentation?

The amount of salt ​ depends very much on the type of fermentation.

Vegetables are fermented with approx. 2-4% of the total weight. That means: 10kg sauerkraut needs between 200g and 400g salt.

ATTENTION : if you add water for your vegetable ferment - for example fermented asparagus tips - then the amount of salt is calculated from the weight of the vegetables plus the weight of the water. That is, 500 g of asparagus + 500 ml of water - require at least 20 g of salt (2%).

Grains often do not need salt unless they are fermented over a very long period of time (e.g. miso or some sourdoughs). Milk and drinks are also usually fermented without salt. However, cheese is salted at the beginning of the ripening process. Meat and fish usually cannot do without salt.

How and where salt is used in the course of fermentation therefore depends on which type of bacterial use you want to promote or suppress. As a rule of thumb, the longer the fermentation takes, the more salt is used.  

I want to eat a low-salt diet, how does it work with fermented foods?

Handle salty fermentslike your salt addition. In other words, add less salt to the other ingredients. The ferment is your source of salt. An example: soy sauce in the soup, fish sauce in the marinade, miso on vegetables replace the salt.

I want to eat as many bacteria as possible? How do I do that?

A lot doesn't necessarily help a lot. Especially if you rarely eat fermented foods, you should not consume large amounts at once. It is more important to eat fermented foods continuously. But the most important thing is to make sure that your ferment is NOT PASTEURIZED and don't cook it yourself above 40 degrees.

Only heat the food slightly, if at all.  

My vegetable ferment does not start to bubble and ferment? What is wrong?

Remote diagnosis is difficult. However, pay attention to the following parameters:

- no heat above 35 degrees

- the start of fermentation takes place at room temperature, not in the refrigerator

- use organic ingredients

- use at least 2% salt on the total weight of your ferment (also include added water)

- do not use salt with added iodine and flow aids

- Make sure that the vegetables to be fermented are always covered with sufficient liquid

If it still does not bubble after 3 days, discard it. Then it won't work anymore.

Do I need a starter culture for fermented vegetables?

No, the natural yeasts on your organic vegetables start fermentation on their own. A starter culture in the form of an "old" ferment juice (eg sauerkraut juice) is not a disadvantage either and can help to get your vegetable ferment going and can be interesting in terms of taste. Make sure your starter culture is unpasteurized.


How long does fermentation have to take place? How do I know when my ferment is ready?

For this question there is no clear answer. When you start fermentation, this statement is a bit unsettling. In the medium term, however, this represents the charm of fermenting.

2 factors are the main drivers and are dependent on each other:

- Temperature: how warm is it?

- Time: How long has it been fermented?

That is, the warmer, the faster and the cooler, the longer you have to ferment.

If you ferment in glasses you can watch the bubbling and clouding process of the brine very nicely. It hisses and works - this process usually stops after a few days and you can taste your ferment. Here are a few pointers:

Sauerkraut - from 5 weeks

Kimchi - from 5 days

Cucumbers - from 2 days

If it tastes good, then you should put it in the refrigerator. That slows down further fermentation to a minimum.

Help my ferment is going over.

In the active phase of fermentation, which usually begins 12 hours after you have pickled the vegetables, the brine really starts to bubble. This sometimes raises the fermentation material or the brine comes out of the glass.  

  • Therefore, always fill your fermentation vessel so that there is still some space for active fermentation

  • For the first week, place the fermentation vessel on a plate and cover the vessel with a cloth so that as much liquid as possible can be caught.

Which tools, which devices do I need?

A jar with a lid and a knife are actually sufficient. However, the following tool tips will help ensure that the fermentation experiment succeeds right from the start:

The right fermentation tank!

For small portions (up to 3 liters), swing glasses are recommended. Your advantage is clearly that fermentation gas can escape through the clip lock, but no impurities can enter.

Anything over 3 liters should be fermented in fermentation pots. The more digestate, the better the result.  

Tamper & Pestle!

It's definitely not a must and nothing your hands can't do too. The use of a tamper is advisable  finely chopped fermentation material (cabbage). On the one hand, it helps that more liquid escapes from the herb and, on the other hand, when filling the fermentation tank, that no air chambers are created.  


Your digestate must be covered with sufficient brine, especially at the beginning. Vegetables floating on the surface can easily get moldy. It is therefore advisable to use weights to hold the digestate under the brine.

How long do my fermented vegetables last?

Laaaaaange. Storage in the refrigerator ensures that fermentation only goes on very slowly. But that also means that your ferment will ripen in the refrigerator. This makes it more acidic and also makes the texture softer. There's a 2 year old red cabbage in my fridge that still tastes lovely.  

Therefore, if you like your vegetables crunchy and not very sour, you should consume them as quickly as possible. For everyone else, the ferment constantly offers new interplay of textures and acids.  

Help. There is a white slimy layer on my fermented vegetables.

Kahm yeast! The good news - it's not dangerous and you can eat it too. The bad news - it doesn't really taste good.  

How can I avoid kahm yeast?

Kahm yeast is often formed when there is too much oxygen or sugar involved.

Therefore, avoid constantly opening your ferment and, above all, leaving it open.  

The addition of sugar promotes the formation of kahm yeast. Work exactly according to the recipe.

Use enough salt - at least 2% of the total filling quantity

Can I remove the kahm yeast?

If only a white veil covers the liquid, the digestate underneath can usually be eaten in the brine without hesitation. In this case, carefully skim off the kahm yeast, pour the ferment into a fresh glass & pour some 2% salt solution or "healthy" brine.

In the case of sauerkraut, the baked layer can usually be removed easily. The cabbage underneath tastes great. However, if your fermentation vessel allows a lot of air to reach the surface of the fermentation material, consider whether a smaller vessel would be better.

Help. My lake has become cloudy.

Many photos on the Internet show brightly colored vegetables on the subject of fermentation, which nestle nicely together in clasp glasses. However, this is not the truth of a properly proceeding fermentation process. After 24 hours at the latest, the brine begins to turn into a milky to mist-gray liquid. The vegetables also turn pale and greyish over time. No reason to worry. You are on the right track.

Help. My fermented vegetables are moldy.

Black, yellow, green and thick furry white mold are a sign that contamination has occurred.

Always pay attention to the following:

  • Your fermentation vessel must be thoroughly cleaned before use. Hot water or wiping with a cloth soaked in schnapps are advisable.  

  • Vegetables do not require air during fermentation. Always use a container that can be closed tightly (see also:  The right fermentation tank!)

  • Only work with clean equipment on clean surfaces.

  • Always use a clean fork when you gradually remove digestate for use. Close the jar again as quickly as possible and place it in the refrigerator.

As a rule, mold only grows on the surface. Therefore, you can actually remove small molds. However, be careful not to touch it directly. Prevent the fine spores of the mold from spreading over your digestate. If you find that your mold is not just on the surface, but is creeping through the digestate, you need to dispose of it.  

Are lacto-ferments, i.e. products of lactic acid fermentation, vegan?

Yes. Lactic acid is produced during fermentation. This is so named because it was the first to be found in fermented milk products. Lactic acid is also produced during the production of sourdough or meat fermentation. As long as you don't use animal products in your vegetable ferment, it'll stay vegan.