Sour Cream has a taste that is mildly acidic or sour. It has been used for a long, long time in Eastern European cooking, and features as well in many German and Russian recipes. The popularity has made its way to America via immigration, even though the Sour Cream is now dolloped on refried beans instead of borscht. And now, it is catching on in Britain.
Traditionally, it was made by letting unpasteurized cream sour naturally from the bacteria in it. The lactic acid produced by the bacteria eating the milk protein would thicken the cream and make it tangy. This can't work anymore because pasteurization will have killed off the bacteria.
Today, producers start with a pasteurized cream of 18% butterfat that has been homogenised to make it thicker (see Extra Thick Single Cream.) A starter culture of bacteria which make the lactic acid is added. (This process is very similar to Crème Fraîche, except Crème Fraîche starts with cream with almost double the butterfat content.) The now-Sour Cream is then re-pasteurized to kill those bacteria and stop the process, which extends of course the shelf life. Stabilizers and/or gelatin are sometimes added.
Lower-fat Sour Creams start with lower-fat creams. Non-fat Sour Cream is made from skim milk, and to make up for the absence of fat, is thickened with things such as starch or gelatin.
Of course, Sour Cream is great with baked potatoes and Mexican food, and as a base for dips. Marketing of it as a topping and a base for dips has been so successful that it is now actually a novelty to use it in cooking. But it is really nice in savoury dishes such as beef stroganoff, or as a tangy substitute for regular cream in soups. There is also a great German recipe for chocolate chip cookies that uses Sour Cream. And, consider using it as a topping for fresh fruit.
Sour Cream is likely to curdle if boiled, so don't let whatever you are putting it into boil. When adding to a soup, add a few spoonfuls of the hot liquid to the Sour Cream first, then tip the warmed-up Sour Cream in at the very end.
Cannot be whipped (just in case the idea ever occurred to you.)
Per cup of Sour Cream, 1 cup of Crème Fraîche. If you're in the UK and have cheap access to Crème Fraîche, you can use that (probably wouldn't make sense in North America substituting a 10 dollar tub of Crème Fraîche for a 79 cent tub of Sour Cream.);
- Per cup of Sour Cream, 1 cup of yoghurt;
- Per cup of Sour Cream, 3/4 fine cottage cheese + 2 tbsp milk + 2 tbsp lemon juice;
- Per cup of Sour Cream, 1/2 cup fine cottage cheese + 1/2 cup plain yoghurt;
- On baked potatoes, try mayonnaise instead. Seriously, it is fabulous.
You can't make Sour Cream at home the way people used to make it on the farms: just setting it aside until it soured enough (unless you have your own cow in the back garden, of course, and very tolerant neighbours.) The cream that you get at supermarkets is pasteurized, which is a good thing because then you're not playing Russian roulette with your porridge. The pasteurization, though, has also killed the bacteria that would have caused the cream to sour; instead, it will simply spoil.
To make your own from store-bought cream, per 2/3 cup / 5 oz / 150ml of 18% fat cream or higher add 1 tsp of lemon juice or vinegar or buttermilk starter, and let stand at room temperature until curdled -- several hours.
8oz Sour Cream = 1 cup = 237 ml (250 ml is close enough)
Sour Cream cannot be frozen. You can keep up to the use-by date (if you can decipher the codes on the package to figure out what that is). If you see pink or green mould, you've missed your chance to use it -- bin it. Even if it looks like the mould is only in one place, there will be threads of mould throughout that you can't see yet.
It's a myth that Mexicans use Sour Cream a lot on their food. They actually use what they call "Crema Agria", for which Sour Cream is our substitute (and a tasty one, at that.)
Literature & Lore
CreamClabber Cream; Clotted Cream; Coffee Cream; Cream of Coconut; Cream; Crema Agria; Crème de Brebis; Crème Fraîche; Double Cream; Extra Thick Double Cream; Extra Thick Single Cream; Half & Half Cream; Heavy Cream; Ice Cream; Non-Dairy Creamer; Nondairy Topping; Rømmekolle; Single Cream; Sour Cream; Whipping Cream
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Soured Cream; Crème aigre, Crème sure (French); Sauerrahm, Saure Sahne (German); Panna acida (Italian); Jocoque, Nata ácida (Spanish); Leche cortada (Portuguese)