If you have ever sunk your teeth into a juicy lime or lemon, you have experienced nature's most concentrated form of citric acid. Found in a variety of vegetables and fruits, citric acid is a weak organic acid and a natural preservative. The acid is also an antioxidant, and is commonly used to add a sour taste to soft drinks and a variety of foods.
Physical Properties
According to the American Chemical Society, at room temperature, citric acid appears either colorless or as a white crystalline powder. The substance is weakly acidic. Citric acid melts at 153 degrees C and decomposes at its boiling point, or above 174 degrees C.
Hazardous Characteristics
The overall toxicity of citric acid is negligible. However, the substance can be irritating if it gets in the eyes or comes in contact with the skin. If inhaled, the white powder may cause a sore throat or induce coughing. Abdominal pain can occur if small amounts are ingested. It can be fatal if doses of 0.5 kg or more are ingested.
Uses
"The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals" notes that citric acid is primarily used as an acidifying agent in beverages, effervescent salts, elixirs, pharmaceutical syrups and to adjust the pH of food. It is also used in jellies, jams, candy and preserves to provide tartness.
References
- American Chemical Society: Citric Acid Properties
- "The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals"; Maryadele J. O'Neil (ed.); 2006
- Solar Navigator: Citric Acid
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