Citric acid is a naturally occurring acid which is found in large quantities in fruits – notably citrus fruits such as oranges, lemons and certain berries. It is a quite weak acid and has a distinct, sour taste.

It is widely used in the food industry as an additive. When added to food products or beverages, Citric acid provides a sharp, sour taste which increases appetite and enhances flavour. It is most common in sour candies and gummy bears in the form of a fine white powder, also known as “sour salt”. Some people specifically add it to their food to alter taste. Besides its use as an additive, the citric acid is also commonly used as a natural food preservative.

This acid is also commonly found in various natural skin products. The acid also exfoliates the skin by removing dead skin cells from the top layer of the skin, thus encouraging new cell growth.

Citric acid is an excellent chelating agent, binding metals by making them soluble. It is used to remove and discourage the build-up of limescale from boilers and evaporators. It can be used to treat water, which makes it useful in improving the effectiveness of soaps and laundry detergents. By chelating the metals in hard water, it lets these cleaners produce foam and work better without need for water softening. Citric acid is the active ingredient in some bathroom and kitchen cleaning solutions. A solution with a six percent concentration of citric acid will remove hard water stains from glass without scrubbing.

Citric acid is used as an odourless alternative to white vinegar for home dyeing with acid dyes.

Citric acid can be used as a lower odour stop bath as part of the process for developing photographic film. Photographic developers are alkaline, so a mild acid is used to neutralize and stop their action quickly, but commonly used acetic acid leaves a strong vinegar odour in the darkroom.