Kiseli kupus (KEE-seh-lee KOO-poos; кисели купус) means “sour cabbage” in Serbian, Croatian, Bosnian and Montenegrin; in Croatia it
is also called kiselo zelje (Croatian Wikipedia). The word covers shredded sour cabbage too, but this page is
about the whole-head kind: heads of white cabbage left in salted water until they turn sour, then used leaf by leaf. Its best-known job
is sarma (from the Turkish for “wrapped”), cabbage leaves rolled around rice or minced meat and cooked. Across Turkey and the Balkans,
sarma is made with both fresh and lacto-fermented cabbage leaves, and a survey of folk cuisines in the region recorded that in Serbia
the cabbage for sarma is “quite exclusively used only lacto-fermented” (Dogan et al., 2015). Bulgarians call sour cabbage
кисело зеле (kiselo zele) (same source).
Sour cabbage is part of zimnica, the stores a household puts up as winter approaches, and as a Serbian daily puts it, “every house
has its own recipe” (Novosti, 2025). The heads go into a barrel or crock in brine, called rasol, so there are cabbage
leaves for sarma all winter (Dogan et al., 2015).
It is sauerkraut made without shredding. Instead of slicing the cabbage and salting it dry, as in our
sauerkraut recipe, you pack whole heads into a crock or barrel and cover them with brine. That one difference
changes how you work out the salt and how long you wait.
Whole Heads Ferment Differently From Shredded Kraut
The only study we found that compared whole heads with shredded cabbage was carried out by a team including the University of
Belgrade. It set shredded cabbage “as is typical in the United States” against whole heads, “a traditional process in parts of Eastern
Europe” (Niksic et al., 2005). Both were fermented at 18 and 22°C with 1.8, 2.25 and 3% salt (the abstract doesn’t say
whether that is of the brine or of the cabbage). The shredded fermentations ran 15 days; the whole heads ran 28. The whole heads ended
at a lower pH, but the shredded kraut had more acid in total.
The study also added E. coli O157:H7 and Listeria monocytogenes to the cabbage on purpose. Neither could be found at
the end of the fermentations, but acid-tolerant strains of both were isolated after 15 days and “could be detected at 35 days in the
wholehead sauerkraut” (same source). That’s a deliberately contaminated lab batch, not a measure of how often home batches carry these
bacteria. It still says something useful: the bacteria lasted longer in whole heads than in shredded kraut, and being sour is not proof
that they have gone.
Cabbage heads are also soured at factory scale: in one 2026 study from the University of Novi Sad, cabbage heads fermented under
industrial conditions for 45 days, with added citric or ascorbic acid (Savić et al., 2026).
Working Out the Salt for Heads in Brine
For shredded kraut the salt is a share of the cabbage’s weight: NCHFP’s 3 tablespoons per 5 pounds is about 2–2.5%
(NCHFP). With whole heads in brine, the salt you dissolve in the water spreads into the cabbage over the first
weeks until heads and brine are about equally salty. So the figure that matters is salt as a share of cabbage plus water, not the
strength of the brine you pour in.
That’s where many recipes go wrong. A brine of 3% (30 g per litre) poured over an equal weight of cabbage evens out at about 1.5%.
Oregon State University Extension lists salt “less than 1.7% concentration” as a cause of soft kraut, and too little salt as a cause of
slimy kraut, which means spoilage (Oregon State). NCHFP’s warning applies here too: “Do not attempt to make
sauerkraut or fermented pickles by cutting back on the salt required” (NCHFP).
Aim for salt equal to 2.5% of the cabbage and water together. For 4 kg of heads covered by 4 litres of water, that’s 8 kg in all
and 200 g of salt, dissolved in the water. The brine itself is then about 5% of the water, which looks strong but evens out to 2.5%.
Some family recipes also pack a spoonful of salt into each cored head; if you do, weigh it, count it in the same total and dissolve that
much less in the water. A household recipe that the Serbian daily Novosti attributes to Bulgarian home cooks, 1.6 kg of salt and 20
litres of water for 50 kg of white cabbage plus a few heads of red, works out to a little over 2% on the same basis
(Novosti, 2025). Our salt and brine calculator does the dry-salt and brine arithmetic for other
vegetables.
Timing, Temperature and When It’s Ready
Keep the crock at 18–22°C (64–72°F), the range the whole-head study used (Niksic et al., 2005). NCHFP’s figures for
sauerkraut point the same way: below 60°F (about 16°C) it may not ferment, and above 75°F (24°C) it may turn soft; at 60–65°F
(16–18°C) NCHFP allows 5–6 weeks even for shredded kraut, so give the cooler end of the range longer (NCHFP).
Plan on at least four weeks. The heads are ready when the leaves are sour and evenly translucent right to the centre, and the brine has
stopped bubbling.
Then move the heads, still covered with their brine, to the fridge (4°C/40°F or below). NCHFP says fully fermented kraut keeps there,
tightly covered, for several months (NCHFP). Some Balkan households keep the barrel in a cellar at 10–12°C from
the start (Novosti, 2025), but that is below the 60°F (16°C) at which NCHFP says kraut may not ferment, and outside the
temperatures the whole-head study tested, so we don’t recommend it.
Check the crock two or three times a week. A flat white film on the brine (kahm yeast) can be skimmed off. Throw the batch out if it
turns slimy, smells rotten or grows fuzzy or coloured mould on the cabbage; our troubleshooting guide explains
the causes of soft or pink kraut.
Raw Salad or Cooked Sarma
In sarma the leaves are rolled around a filling and cooked (Dogan et al., 2015), which heats them through. Kiseli
kupus is also eaten raw, sliced as a salad. Because the whole-head study could still find acid-tolerant Listeria and
E. coli a week after its heads were fully fermented, and the abstract reports nothing beyond 35 days, sourness alone doesn’t tell you the
heads are free of them. Cooking does. CDC lists pregnant women, newborns, adults aged 65 or older and people with weakened immune
systems as the groups for whom Listeria infection can be especially harmful (CDC), and children under 5 as more
likely to become seriously ill from E. coli (CDC). For all of them, eat kiseli kupus cooked. Northeast China makes a close relative from napa cabbage halves: suan cai.
The brine, rasol, is drunk on its own too (kraut juice). It is raw, so the same rule applies: only from a batch
that is fully sour, and not for the groups above. It is also very salty. At 2.5% salt a litre of rasol carries about 25 g of salt, or
about 10 g of sodium, so a 250 ml glass has about 2.5 g of sodium, more than the WHO’s adult limit of less than 2 g a day
(WHO).
For how long finished sour cabbage keeps in the fridge, the same rules as for kraut apply: see
how long sauerkraut lasts. For a mixed jar of whole Balkan vegetables in brine, see
turšija.