Fermenting at home: how to make sauerkraut

This is the second article of a series dedicated to home fermentation. Updated May 27, 2022.

Sauerkraut is as old as history. Pliny the Elder, a 1st century Roman naturalist, describes in his encyclopedia how barbarians already handled the fermentation of cabbage in clay pots with complete skill, and some authors, such as the German anthropologist Wolf-Dieter Storl, say that the workers of the Great Wall of China consumed it in their tasks, in the year 220 BC.

That it’s an ancient food isn’t motivation enough to make it at home? Probably not, but knowing your age can give the kitchen and cold days something epic – what better than to accompany this Catania game with a serving of aromatic sauerkraut alongside a pitcher of beer – and serve also to understand its nutritional value.

If it was eaten by warriors, by builders of huge monuments, by people far north, and then by navigators, like Captain James Cook, who always carried several barrels to prevent scurvy in his crew —, it is because sauerkraut —or Sauerkrautin German, brought them many vitamins C and K, as well as calcium, magnesium, iron and potassium.

But according to North American Sandor Katz, one of the world’s most popular fermentation promoters, the most important thing about sauerkraut is the probiotics it contains, microorganisms that only appear during the fermentation process, which is achieved by leaving the cabbage, after salting and finely chopping it, immersed in its own liquids for several weeks.

“When we eat them,” Katz said at a conference in Spain in 2016 “all these microorganisms will help the intestinal microbiota to better fulfill its functions of food assimilation, improve the immune system and stop the pathogenic germs that can threaten us”.

But why do I have to make sauerkraut at home and wait 10-21 days, when I can buy a bag from the supermarket? “Because industrial sauerkraut is usually cooked and preserved in vinegar, and when pasteurized and subjected to high temperatures, all of its microorganisms die. It therefore does not contain probiotics or any of the benefits of sauerkraut naturally fermented,” says Jéssica Márquez, founder of fermentation . His company, created in 2019, also produces kimchi, the traditional Korean preparation, but his strength is the Sauerkraut.

“Doing it at home, moreover, is very easy”, adds nutritionist Trinidad Völker, partner of the fermenter which for nearly five years has been manufacturing and marketing five types of Sauerkraut -all naturally fermented-, apple cider vinegar, kimchi and beet rootsa more recent ferment, based on beets.

Both explain here how to do it and what is needed. “The main thing: patience,” warns Jéssica.

The main thing, explain the two, is not to have a fancy fermentation jar or a powerful knife or a delicate wooden board. “The most important thing is the cabbage,” explains Trinidad Völker. It can be curly or purple but as fresh as possible, hopefully organic and not too battered. Anything that has been waiting for a destination in the back of the refrigerator for several weeks can be used, but it will probably release less juice and have less flavor.

How much cabbage do you need to make sauerkraut? It all depends on the space we have to store. A standard one-litre canning jar, for example, is ideal for one kilo of cabbage, which is the normal weight of half a unit of this vegetable.

“You can grate it with a mandolin, but I recommend chopping it with a knife,” says Jéssica Márquez. “It’s slower but you have better control over the cut: if it’s very fine, as is usually the case with a grater, the sauerkraut ends up like porridge, without consistency”, explains Trinidad. “And if it’s too thick, it will release less liquid and it won’t ferment as well.”

The outer leaves, which are softer, dirty and less crispy, should I throw them away? “Nope !” Jessica exclaims. “It will help us later.” The rod, yes, it is not recommended to use it.

Salt is irreplaceable. “It has two functions: on the one hand, it releases water from the vegetable – thanks to osmotic pressure -, and on the other hand, it prevents the action of bacteria which degrade the cabbage”, explains Jéssica .

You need to add it after chopping the vegetables. How much? Between 1.5 and 3 percent of the weight of the cabbage. “That is to say, if you make a kilo of cabbage, there should be 15 or 20 grams of salt”, explains Trinidad Völker. Something like a level tablespoon.

Once mixed in a bowl—never metal—let them rest for a few minutes. If the cabbage is purple, which is usually drier, the founder of La Fermentista recommends waiting half an hour. Then comes the “massage”: with the hands you have to squeeze the salted vegetables, a kind of kneading so that it releases its liquids.

There is a difficult debate among fermenters regarding the type of salt. “I prefer the sea,” says Jéssica, from Fermentastik. “It has more minerals and nutrients, like potassium, which helps offset the sodium. Refined foods also do not promote fermentation.

Trinidad doesn’t care. “In the past, all the salt came from the sea,” he says. “The difference in result does not seem great to me and I wonder about the conditions of the sea salt: there may be, for example, microplastics, and we do not know.”

When it seems like you’re out of juice to throw away, it’s time to bottle the cabbage. There are vessels specially designed for fermentation, both glass and ceramic, which are equipped with semi-circular stones to immerse the vegetables – and therefore have no contact with oxygen, the worst enemy of the sauerkraut – and an airlock, which lets the gases produced by the bacteria escape but does not allow anything to enter inside.

“This allows for a more controlled fermentation, but it is not essential”, explains Trinidad Völker. “With a one liter canning jar, or better if there are two, it’s fine.” Do not forget to sterilize it beforehand, for at least five minutes in boiling water.

When transferring to the jar – which cannot be aluminium, metal or plastic, as these are materials that the acid of fermentation can corrode – it is essential that the cabbage is as compact as possible, to avoid air leaks. Then it is covered with the same liquid released by the vegetable, making sure that no piece is left out of the water.

“It is an anaerobic fermentation, that is to say without oxygen”, explains Jéssica Márquez. “That’s the most important thing in the whole process: that everything is submerged,” adds Trinidad. “Otherwise, unwanted fungi or bacteria may enter, which can spoil all the content.”

This is where the large outer leaves that we reserved at the start come into play: after having washed them well, they can be folded and used as weights to hold the cabbage under the liquid. As Jéssica says, “they work like a cork”.

Now we just have to wait. “Ideally,” says Márquez, “it should be around 18 degrees, in a cool, dry environment.” But at that time, when we reach this temperature for a few days, the jar should be left in a place that is not too cold, so that the process activates and does not take too long.

“It doesn’t matter if it’s daytime or not, and if you leave it in the sun, nothing happens,” says Völker. The minimum, to obtain a product with a good dose of probiotics and an interesting flavor, is that it ferments for ten days. This means that the bottle must maintain the initial conditions during this time, opening it briefly, every one or two days, to release the gases.

But it can take more than a month. “The longer it is, the more acidic it will taste,” says Jéssica, from Fermentastik. “But not necessarily more bacteria,” adds Völker. “The peak comes on average on day 21. That’s when it has the best flavor and the most nutrients.”

If you managed to wait those three weeks, open the jar, discard the large leaves, and refrigerate. It can last for months there. “For it to keep well, cutlery containing other foods should not be used, to avoid cross-contamination,” warns Trinidad, from La Fermentista.

To accompany the cabbage, and make the flavor more complex, you can add other vegetables or spices, following the same process. “The grated carrot works very well, the turmeric, which is an antioxidant, a little ginger, the apple ferments very well, and fresh herbs like thyme or rosemary will give it good aromas,” says Márquez. “Eating a spoonful a day,” promises Völker, “will improve your digestion, you’ll absorb more nutrients, and your menu will be richer. It’s very addictive.”

*Prices for products in this item are updated as of May 27, 2022. Values ​​and availability may change.