Sour cream

Sour cream is a dairy product obtained by fermenting regular cream with certain kinds of lactic acid bacteria. The bacterial culture, which is introduced either deliberately or naturally, sours and thickens the cream. Its name comes from the production of lactic acid by bacterial fermentation, which is called souring.

Traditionally, sour cream was made by letting cream that was skimmed off the top of milk ferment at a moderate temperature. The bacteria that developed during fermentation thickened the cream and made it more acidic, a natural way of preserving it.

Traditional sour cream contains from 18 to 20 percent butterfat and gets its characteristic tang from the lactic acid created by the bacteria.

Commercially produced sour cream usually contains 14 percent milk fat, and can contain additional thickening agents such as gelatin, rennet, guar gum and carrageenan, as well as acids to artificially sour the product.

Light, or reduced-fat, sour cream contains less butterfat than regular sour cream, because it is made from a mixture of milk and cream rather than just cream. Fat-free "sour cream" contains no cream at all, and is made primarily from non-fat milk, modified cornstarch, thickeners and flavoring agents.

Sour cream is not fully fermented, and like many dairy products, must be refrigerated unopened and after use. It is sold with an expiration date stamped on the container, though whether this is a "sell by", a "best by" or a "use by" date varies with local regulation. Refrigerated unopened sour cream can last for 1–2 weeks beyond its sell by date while refrigerated opened sour cream generally lasts for 7–10 days.

Cultured cream: grade A whey, modified food starch, sodium phosphate, sodium citrate, guar gum, carrageenan, calcium sulfate, potassium sorbate, and locust bean gum.

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