It is responsible for the tart taste of various fruits in which it occurs, e.g., lemons, limes, oranges, pineapples, and gooseberries. It is obtained also by fermentation of glucose with the aid of the mold Aspergillus niger and can be obtained synthetically from acetone or glycerol.
Citric acid is used in soft drinks and in laxatives and cathartics.
Its salts, the citrates, have many uses, e.g., ferric ammonium citrate is used in making blueprint paper. Sour salt, used in cooking, is citric acid.