Sour cream came to the United States by way of Eastern and Central European immigrants in the 19th century, who had a habit of mixing the tangy, thick condiment into stews and soups, such as goulash and borscht.
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 (part of milk's natural way of preserving itself). Now that most milk is available pasteurized, which kills off even helpful bacteria, fermentation is kick-started by adding these bacteria back in.
Sour cream is very similar to its French cousin, crème fraîche, but with less fat, more acidity, and a thicker texture. The lesser fat content of sour cream makes it less versatile for cooking—while crème fraîche can be boiled, sour cream will curdle if heated too high or too quickly. It is best to add sour cream to a dish just before serving. However, sour cream is frequently used to add richness and tang to baked goods, such as cakes, scones, and even pastry.
Light sour cream has at least 50 percent less fat than the regular version and is made from half and half (equal parts cream and milk).
Fat-free sour cream is thickened with stabilizers like plant gums and is not recommended as a substitute for sour cream in cooking and baking.
HOW TO STORE
Refrigerate it for up to a week after the date stamped. If any mold forms on sour cream, throw it out.
