Sour cream is a dairy product rich in fats obtained by fermenting a regular cream by certain kinds of lactic acid bacteria. The bacterial culture, introduced either deliberately or naturally, sours and thickens the cream. Though only mildly sour in taste, the name stems from the production of lactic acid by bacterial fermentation, sometimes referred to as ``souring``.//
Sour cream, made out of cream, contains from 12 to 16 percent butterfat (about 14 grams per 4 ounce serving), and gets its characteristic tang from the lactic acid created by the bacteria. Commercially produced sour cream often contains additional thickening agents such as gelatin, rennin, guar and carrageen, as well as acids to artificially sour the product.
Light sour cream contains about 40 percent less butterfat than regular sour cream because it is made from a mixture of milk and cream rather than just cream.
Non-fat sour cream is thickened with stabilizers and thickeners such as corn starch, gelatin, carrageenan, and guar gum, and contains no or trace amounts of butterfat.
Sour cream is not fully fermented, and as such must be stored under refrigeration. As with other dairy products, it is usually 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. Food authorities, such as the USDA, advise that sour cream with visible mold should be discarded, as it may be contaminated below the surface and could contain dangerous mycotoxins and aflatoxin.
Used primarily in the cuisines of Europe and North America, sour cream is often used as a condiment. It is a traditional topping for baked potatoes, added cold along with chopped fresh chives. It is used as the base for some creamy salad dressings and can also be used in baking, added to the mix for cakes, cookies, American-style biscuits, doughnuts and scones. It can be eaten as a dessert, with fruits or berries and sugar topping. In Central America, crema, a variation of sour cream, is a staple ingredient of a full breakfast. Sour cream can also provide the base for various forms of dip used for dipping potato chips or crackers, such as onion dip. In Tex-Mex cuisine, it is often used as a substitute for crema in nachos, burritos, taquitos or guacamole. It is one of the main ingredients used in Beef Stroganoff. Sour cream flavoring can also be found in snack foods such as Pringles, to which onion flavor has also been added.