Applications

The dominant use of citric acid is as a flavoring and preservative in food and beverages, especially soft drinks. Within the european number it is denoted by E number E 330  . Citrate salts of various metals are used to deliver those minerals in a biologically available form in many dietary supplements. 

Foods, other

Citric acid can be added to ice cream as an emulsifying agent to keep fats from separating, to caramel to prevent sucrose crystallization, or to recipes in place of fresh lemon juice.  Citric acid is also often used in cleaning products and sodas or fizzy drinks.

Citric acid sold in a dry powdered form is commonly sold in markets and groceries as "sour salt", due to its physical resemblance to table salt. It has use in culinary applications where an acid is needed for either its chemical properties or for its sour flavor, but a dry ingredient is needed and additional flavors are unwanted (e.g., instead of vinegar or lemon juice).

Cleaning and chelating agent

 Citric acid is the active ingredient in some bathroom and kitchen cleaning solutions. A solution with a 6% concentration of citric acid will remove hard water stains from glass without scrubbing. In industry, it is used to dissolve rust from steel. Citric acid can be used in shampoo to wash out wax and coloring from the hair.

Cosmetics and pharmaceuticals

Citric acid is widely used as a pH adjusting agent in creams and gels of all kinds. In this role, it is classified in most jurisdictions as a processing aid and so does not need to be listed on ingredient lists.

Citric acid is an alpha hydroxy acid and used as an active ingredient in chemical peels.

Citric acid is used as one of the active ingredients in the production of antiviral tissues.

Dyeing

Citric acid can be used in food coloring to balance the pH level of a normally basic dye. It is used as an odorless alternative to white vinegar for home dyeing with acid dyes. 

Qualitative analysis

Sodium citrate, the sodium salt of citric acid, is used as a chelating agent and is present in the  Benedict´s reagent , used for identification both qualitatively and quantitatively, of reducing sugars.

Industrial and construction

Citric acid can be used as a successful alternative to nitric acid in  passivation of  stainless steel.

Safety

As a weak acid, exposure to pure citric acid can cause adverse effects: inhalation may cause cough, shortness of breath, or sore throat; ingestion may cause abdominal pain and sore throat; exposure to skin or eyes may cause redness or pain.Long term or repeated consumption may cause erosion of tooth enamel.