Citric acid

A white powder extracted from the juice of citrus and other acidic fruits (such as lemons, limes, pineapples and gooseberries). it's also produced by the fermentation of glucose. Citric acid has a strong, tart taste and is used as a flavoring agent for foods and beverages. Small bottles of crystallized sour salt (also called citric salt) are often found in the kosher-foods section of supermarkets. Sour salt is used to impart a tart flavor to traditional dishes such as Borscht.