Citric acid is a weak organic acid found in citrus fruits. It is a natural preservative and is also used to add an acidic (sour) taste to foods and soft drinks. In biochemistry, it is important as an intermediate in the citric acid cycle and therefore occurs in the metabolism of almost all living things. Uses & Benefits of Citric Acid Used as Cleaning and chelating agent. Used as home dyeing with acid dyes. Used to control pH in household cleaners and pharmaceuticals. Used as passivation of stainless steel. Used in the process for developing photographic film. Citric acid is an excellent soldering flux. Citric acid is prominent flavoring and preservative in food and beverages.