🥣 Sour cream

Smetana (sour cream) is a thick fermented dairy product made by souring cream with lactic acid bacteria. Under the Codex Alimentarius it is fermented cream: the microorganisms lower its pH, and it thickens. ² In the EU the name "smetana" is reserved for dairy products only, so a blend with vegetable fats may not use it. ³

What the Codex requires. Fermented cream must contain at least 10% milk fat. Besides the starter, salt may be added, and rennet too, but only to improve texture, not to curdle the cream. If the label names specific bacteria, they must stay alive until the end of the shelf life; if the product is heat-treated after fermentation, live bacteria are not required. ²

Fermented and acidified. The Codex separately defines acidified cream, in which acids or acidity regulators are added directly, without bacteria. ² So a thick sour product is not always a fermented one.

The law on the name. In the EU, "smetana" stands in one list with cream, butter, cheese, yoghurt and kefir: these names may be given only to milk products. Other substances may be added, but only if they do not replace any milk constituent. ³

How the dairy makes it. The cream is standardised for fat, homogenised and heat-treated, usually for 5 minutes at 90 °C. It is then cooled to 18–21 °C, a lactococcal starter is added and it ferments for 18–20 hours; the aroma comes from particular strains that produce diacetyl. Such products contain 10–12% or 20–30% fat. The finished smetana is cooled quickly so that it does not sour further. ⁴

Why smetana turns bitter. During long storage, bacterial enzymes break down the protein beta-lactoglobulin and bitterness appears. Carbon dioxide and aroma escape through the pack, and in a poorly sealed pack yeasts and moulds may grow on the surface. ⁴

At the table. Smetana is traditional in Eastern and Central European cooking: it goes into borscht and soups, with dumplings and pancakes, into salads, sauces and baking. According to the USDA, 100 g of cultured sour cream has 198 kcal, 19.4 g fat (10.1 g saturated), 2.44 g protein and 101 mg calcium. ¹

Smetana or cream? Cream is the sweet, unsoured fat of milk, whereas smetana is soured with lactic acid bacteria and thickens as the pH falls. It also differs from acidified cream, a separate Codex product where acids are added directly, without bacteria, so a thick sour product is not always a fermented one. Under the Codex fermented cream needs at least 10% milk fat. In the EU a blend with vegetable fats may not be called smetana.

Look for the name “sour cream” or “smetana” and read the ingredients: only cream and a starter culture. A blend with vegetable fats may not use the name in the EU. Fat is usually 10–12% or 20–30%. Choose a closed pack from the chilled shelf of a supermarket or a delicatessen with Eastern European food, and keep it in the fridge at 0–5 °C. If the label names specific bacteria, they must stay alive to the end of the shelf life.

Why it matters to you. Read the label: the ingredients should be only cream and starter, and a blend with vegetable fats is no longer smetana. ³ The NHS counts sour cream among fatty foods and suggests reduced-fat versions or plain low-fat yoghurt in recipes. ⁵ Keep it in the fridge at 0–5 °C in a closed pack. ⁴ In pregnancy, eat only smetana made from pasteurised cream. ⁶