How to make Polish sauerkraut in a jar

To ferment cabbage in a jar, shred it finely, mix it with salt and leave it until it releases its juice. Pack it firmly into a clean jar so the juice completely covers the cabbage. Leave room beneath the lid and let it ferment at room temperature, then refrigerate once it has soured to your taste.

Ingredients and equipment

For a batch that should fit into a jar of about 1.5 litres once packed, prepare:

• 1 kg white cabbage, weighed after trimming
• 20 g non-iodised salt or ordinary food-grade salt without added flavourings
• Optional: 1 small carrot, coarsely grated
• Optional: a few caraway seeds

You will need a clean, scalded jar, a clean bowl, a knife or shredder, and a wooden tamper or spoon. A small fermentation weight is useful for keeping the cabbage beneath the juice. If adding carrot, include its weight in the kilogram of vegetables and weigh the salt according to the total. The ratio of 20 g salt per kilogram of vegetables helps produce a suitably salty ferment.

Shredding and salting the cabbage

Remove damaged and dirty leaves, cut out the hard core and thinly shred the cabbage. Even strips are easier to pack. Place the cabbage in a large bowl, sprinkle with the weighed salt and mix thoroughly. Add the carrot or caraway now if using.

Massage the vegetables with clean hands for several minutes. The cabbage should soften and begin to release juice. Leave for 30 minutes, then mix and massage again. Young, juicy cabbage may release liquid faster than a firm head that has been stored longer. Keep the juice: it is needed to cover the vegetables.

Packing the jar and starting fermentation

Add the cabbage to the jar in batches, pressing each layer down firmly. This pushes out air and raises the juice above the surface. Leave a few centimetres of space at the top, as the contents may rise during fermentation. Place a clean weight on top and press the cabbage beneath the liquid.

If there is not enough juice after packing, add cooled brine made with 20 g salt per litre of boiled water. The vegetables must remain submerged. Fit a fermentation lid or rest an ordinary lid loosely on top so gas can escape. Place the jar on a plate to catch any overflow. Do not seal the jar tightly during active fermentation.

Checking the flavour and storing

Keep the jar at room temperature, away from direct sunlight. Check daily that the cabbage is beneath the juice and that gas can escape. Bubbles, a sour smell and cloudy liquid are typical signs of fermentation. After a few days, taste the cabbage with a clean fork. When it is as sour as you like, close the jar and refrigerate it, where fermentation will slow considerably.

If fluffy mould, pink or orange discolouration, or a rotten smell appears, discard the entire contents. Do not simply remove the affected layer. Always use clean utensils to serve and keep the remaining cabbage covered with liquid.

Ways to use sauerkraut

Jarred sauerkraut works in a slaw with apple and onion or as a pierogi filling. Add it to soup or use it to make bigos. Taste it before cooking: if very sour, rinse it briefly, bearing in mind that this also softens its flavour.

The same principle of keeping vegetables submerged is used for lightly fermented cucumbers. Cabbage does not need a large amount of added water, however, because properly massaged cabbage usually releases its own juice.

FAQ

How long does cabbage take to ferment in a jar?

A first taste after a few days is usually worthwhile. The time depends on the temperature, how finely the cabbage is shredded and how sour you want it. Cold slows fermentation, while warmth speeds it up.

Should I pierce the cabbage during fermentation?

This is not necessary if it has been packed firmly and gas can escape freely. More important is checking daily that the cabbage stays submerged and the lid does not block the gas.

Can I ferment cabbage without carrot?

Yes. Cabbage and salt are enough. Carrot adds colour and mild sweetness, but it is optional.