cupful sour cream

Sour cream is a cultured dairy product produced by fermenting regular cream with lactic acid bacteria (typically Lactococcus lactis). The fermentation process lowers the pH and thickens the cream, producing a tangy, slightly acidic product with a rich, smooth texture. Commercial sour cream typically contains 18-20% milk fat and maintains a pH of approximately 4.5. The distinctive sour flavor develops from lactic acid production during fermentation, while the thick consistency results from milk protein coagulation and the formation of bacterial polysaccharides.

Sour cream serves as both a cooking ingredient and a condiment across numerous culinary traditions. It is essential in Eastern European cuisines, appearing in borscht, stroganoff, and as a topping for blini and pierogi. In North American cooking, it is commonly used in baking (cakes, muffins, quick breads), as a base for dips and sauces, and as a condiment for baked potatoes and Mexican dishes. The acidity of sour cream reacts with baking soda to provide leavening, while its fat content contributes richness and tenderness to batters. It can be used to finish soups, to marinate meats, or to enrich salad dressings.