Citric Acid C6H8O7
CAS No. 77-92-9, 2-hydroxypropane-1, 2, 3-tricarboxylic acid, 3-carboxy-3-hydroxypentanedioic acid
Citric Acid, also known internationally as CAS 77-92-9 is a weak organic acid. It's a natural preservative and it's often used as an additive to create a sour taste to some foods and soft drinks, beer and seltzer. Citric acid can also be used as a cleaning agent.
Citric acid comes from a variety of fruits and vegetables, most notably citrus fruits. Lemons and limes have particularly high concentrations of citric acid. As much as 8% of the dry weight of these fruits can be citric acid. The concentration of citric acid in oranges and grapefruits is also very high depending on the circumstances in which the fruit was grown.
At room temperature, citric acid is a white crystalline powder. It can either exist in an anhydrous (water-free) form or as a monohydrate. The anhydrous form crystallizes from hot water but the monohydrate forms when citric acid is crystallized from cold water. The monohydrate can be converted to the anhydrous form by heating above 70 degrees centigrade.
The worldwide production of citric acid is approximately 1,600,000 metric tons and approximately 50% of it is produced in China. About 50% of all of the world's citric acid is used in beverages. Approximately 20% of the world's citric acid is used in other food applications and 20% is used for detergent applications. The 10% balance is used in cosmetics, pharmaceutical applications and within the chemical industry.
The uses for citric acid are varied. Citric acid is used for biological applications, for cleaning purposes, in cosmetics, for pharmaceutical applications, for dyeing, in foods, in beverages, for personal care products, for photography and for numerous industrial and construction applications. For example, citric acid is used in the production of soaps, shampoo, laundry detergents and kitchen cleaning solutions. It is commonly used in food coloring to balance the pH level of a normally basic dye. But citric acid is most often used as a preservative or flavoring agent in many foods and beverages, especially soft drinks and sometimes beer. Citric acid may also be used as a ripening agent in the first steps of making mozzarella cheese.
In the industrial sector, citric acid is often used as an alternative to nitric acid in the production of stainless steel. It's also used to slow the setting of Portland cement and for the removal of rust from steel. Due to its low cost of production, citric acid is also used in the production of inexpensive wines where fruits containing little or no natural acidity are used.
Finally, as a flavoring, citric acid is often used for its sour flavor as a substitute for vinegar or lemon juice.
