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 stems from the production of lactic acid by bacterial fermentation, which is called souring. The taste of sour cream is only mildly sour.

Traditional

Traditionally, sour cream was made by letting cream that was skimmed off of 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 — about 22 grams per 120 milliliter serving;— and gets its characteristic tang from the lactic acid created by the bacteria.

Commercial varieties

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.