Twenty percent. That is the number that explains smetana, and almost
everything else follows from it. Smetana runs 20–30% fat against roughly 18–20% for a
standard American sour cream tub — and at the lower end of that range, things start
going wrong in the pan.
Why the percentage decides everything
Fat is what keeps a cultured cream stable when it meets heat. Above about 20%, the
emulsion survives being stirred into hot soup. Below it, the proteins tighten, the water
separates, and you get the grainy curdled mess people blame on the recipe.
Ukrainian recipes therefore name the number — “smetana 20%” — because it is not a
nutrition label, it is an instruction.
Below the number
Light sour cream at 10–15% is for cold use only: a dollop on a salad, a dip. Put it in
a hot pot and it will split, no matter how carefully you stir.
Above it
Crème fraîche sits at around 30% and behaves almost identically to smetana, including in
hot soup. It is the closest substitute there is, and the only drawback is price.
When you cannot find the number at all
Two workarounds, both reliable:
- Raise the fat. Stir a tablespoon of heavy cream into every 100 g of
sour cream. It lifts the percentage enough to matter. - Temper it. Add a ladle of the hot liquid to the sour cream first,
then pour the mixture back into the pot. This works even with the low-fat stuff.
Greek yogurt matches the texture but not the chemistry — it curdles readily and tastes
sharper. Fine as a cold garnish, risky in a hot dish.
Where the number stops mattering
In baking. Once there is flour and sugar involved, sour cream, smetana and thick yogurt
are interchangeable and nobody will tell the difference.
And where no number is given
Assume 20%. That is what a Ukrainian recipe means when it just says smetana.
Also in the reference:
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What is ryazhanka ·
Can you freeze sour cream ·
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