about ½ cup sour cream

Sour cream is a dairy product produced by fermenting regular cream with lactic acid bacteria cultures, typically Lactobacillus lactis. This fermentation process lowers the pH and thickens the cream while developing its characteristic tangy flavor and smooth, spoonable texture. The final product contains a minimum of 18% milk fat in the United States and remains stable due to its acidic environment. It differs from crème fraîche, which uses different bacterial cultures and has a higher fat content, resulting in a milder flavor.

Sour cream is widely available in commercial forms, with variations including reduced-fat and fat-free versions, though these contain stabilizers and thickening agents to compensate for the reduced fat content. The ingredient originated as a natural byproduct of cream storage in cooler climates, later refined into a controlled fermentation process.

Sour cream functions as both a cooking ingredient and a condiment across numerous cuisines. In baking, it adds moisture and richness to cakes, quick breads, and cookies while reacting with baking soda to create lift. In savory dishes, it serves as a finishing element for baked potatoes, tacos, and chili, or as a base for sauces and dressings, particularly in Central and Eastern European cuisine. It is also used in dips, as a marinade component, and to enrich soups and stews. Its acidity balances rich dishes, while its tang complements both mild and spiced foods.