Citric Acid by Ray Sahelian, M.D.
April 8 2015

 

Citric acid is responsible for the tart taste of many fruits where it is found. It is present in citric fruits such as lemons, limes, oranges, and pineapples. Citric and lactic acid are organics acids used primarily in the food and beverage industry as acidulent and preservative. Other commercially important acids are malic, fumaric and tartaric. Citric acid is well known as the source of tart flavor from fruit juices, lactic acid is known to those who exercise hard as an incomplete respiration product in the human body.

 

Where is citric acid found?
Citric acid is used in soft drinks and in laxatives and cathartics. Its salts, the citrates, have many uses, e.g., ferric ammonium citrate is used in making blueprint paper. Sour salt, used in cooking, is citric acid.

 

How is citric acid made?
Citric and lactic acids are produced by fermentation which utilized a carbohydrate source such as corn based starch and sugar beet molasses. Fermentation yields a crude purity product which requires further refining. One refining technique utilities a precipitation process, this process first uses lime to produce calcium citrate solids, this is then contacted with sulfuric acid which produces a partially purified soluble citric acid and calcium sulfate by product. Another technique used is solvent extraction. These processes produce streams which require demineralization by ion exchange.
     Citric acid can be extracted from the juice of citrus fruits by adding calcium oxide (lime) to form calcium citrate, an insoluble precipitate that can be collected by filtration; the citric acid can be recovered from its calcium salt by adding sulfuric acid. Citric acid is obtained also by fermentation of glucose with the aid of the mold Aspergillus niger and can be obtained synthetically from acetone or glycerol.
 

Citric acid cycle
Also called Kreb's cycle or tricarboxylic acid cycle, the citric acid cycle is a series of enzymatic reactions in aerobic organisms involving oxidative metabolism of acetyl units and producing high-energy phosphate compounds, which serve as the main source of cellular energy.
   The name citric acid cycle is derived from the first product generated by the sequence of conversions, i.e., citric acid. The reactions are seen to comprise a cycle inasmuch as citric acid is both the first product and the final reactant, being regenerated at the conclusion of one complete set of chemical rearrangements. Citric acid is a so-called tricarboxylic acid, the chemical formula containing three carboxyl groups (COOH). Hence the Krebs cycle is sometimes referred to as the tricarboxylic acid (TCA) cycle.

 

Additional links
wild yam and berries

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Citric Acid Anhydrous USP