what citric acid do?

It’s one of the most common food additives found in our food supply today, yet for many of us it remains a mysterious ingredient. In some countries, citric acid has been used as an additive in foods, cosmetics and many other products for more than 100 years, mostly as a preservative and flavor enhancer. 

Citric acid was first derived from lemon juice by a Swedish researcher in 1784. It can exist either in an anhydrous(water-free) form or as a monohydrate. The anhydrous form crystallizes from hot water, while the monohydrate forms when citric acid is crystallized from cold water. The monohydrate can be converted to the anhydrous form at about 78 °C. Citric acid also dissolves in absolute (anhydrous) ethanol  at 15 °C. It decomposes with loss of carbon dioxide above about 175 °C.

International Situation

World wide annual production in 2007 stood at approximately 1,700,000 metric tons. More than 50% of this volume was produced in China. Others in Thailand,Europ,The United tate,Canada,Brazil.

More than 50% was used as an acidulent in beverages and approximately 20% was used in other food applications. Another 20% was used for detergent applications, and 10% was used in the production of non-food related products such as cosmetics, pharmaceuticals, and in the chemical industry.

Application

Food and drink

Because it is one of the stronger edible acids, the dominant use of citric acid is as a flavoring and preservative in food and beverages, especially soft drinks and candies.

Citric acid can be added to ice cream as an emulsifying agent to keep fats from separating, to caramel to prevent sucrose crystallization, or in recipes in place of fresh lemon juice. 

Cleaning and chelating agent

Citric acid is an excellent chelating agent, binding metals by making them soluble.

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 can be used in shampoo to wash out wax and coloring from the hair.

In industry, it is used to dissolve rust from steel and passivate stainless steels.

Cosmetics, pharmaceuticals, dietary supplements, and foods

Citric acid is used as an acidulant in creams, gels, and liquids. Used in foods and dietary supplements, it may be classified as a processing aid if it was added for a technical or functional effect.

Aailability of Citric Acid

Citric acid can be bought in powder form and is usually available in stores with other home canning supplies. Citric acid can also be found in natural food stores or health food stores with other vitamins and dietary supplements. In some grocery stores, citric acid is sold in small shakers and labeled as "sour salt."