Cuticle Creams, Softeners

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. more...

Home
Bath & Body
Dietary Supplements,...
Hair Care
Hair Removal
Health Care
Makeup
Massage
Medical, Special Needs
Nail
Acrylic Nails, Tips
Cuticle Creams, Softeners
Files, Implements
Hand Cream
Manicure Kits
Nail Art
Nail Dryers
Nail Polish
Other Items
Paraffin Spas
Pedicure & Foot Spas
Pedicure Kits
Natural Therapies
Oral Care
Skin Care
Vision Care

In biochemistry, it is important as an intermediate in the citric acid cycle and therefore occurs in the metabolism of almost all living things. It also serves as an environmentally benign cleaning agent and acts as an antioxidant.

Citric acid exists in a variety of fruits and vegetables, but it is most concentrated in lemons and limes, where it can comprise as much as 8% of the dry weight of the fruit.

Properties

At room temperature, citric acid is a white crystalline powder. 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 by heating it above 74 °C. Citric acid also dissolves in absolute (anhydrous) ethanol (76 parts of citric acid per 100 parts of ethanol) at 15 degrees Celsius.

Chemically, citric acid shares the properties of other carboxylic acids. When heated above 175 °C, it decomposes through the loss of carbon dioxide and water.

History

The discovery of citric acid has been credited to the 8th century alchemist Jabir Ibn Hayyan (Geber). Medieval scholars in Europe were aware of the acidic nature of lemon and lime juices; such knowledge is recorded in the 13th century encyclopedia Speculum Majus (The Great Mirror), compiled by Vincent of Beauvais. Citric acid was first isolated in 1784 by the Swedish chemist Carl Wilhelm Scheele, who crystallized it from lemon juice. Industrial-scale citric acid production began in 1860, based on the Italian citrus fruit industry.

In 1893, C. Wehmer discovered that Penicillium mold could produce citric acid from sugar. However, microbial production of citric acid did not become industrially important until World War I disrupted Italian citrus exports. In 1917, the American food chemist James Currie discovered that certain strains of the mold Aspergillus niger could be efficient citric acid producers, and Pfizer began industrial-level production using this technique two years later.

Production

In this production technique, which is still the major industrial route to citric acid used today, cultures of Aspergillus niger are fed on sucrose to produce citric acid. After the mold is filtered out of the resulting solution, citric acid is isolated by precipitating it with lime (calcium hydroxide) to yield calcium citrate salt, from which citric acid is regenerated by treatment with sulfuric acid.

Read more at Wikipedia.org