What is citric acid
What is citric acid
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Citric acid is a kind of organic acid which is contained a lot in plums and lemons. Citric acid is acid taste component in these fruits.


In 1937, Mr. H.A. Krebs who is a biochemist in the UK first clarified the mechanism which human beings ingest food and create energy to maintain life, that is, the actual state of vivo metabolism.

He discovered citric acid played the most important role as a leading part. This discovery is famous theory of Krebs’s cycle or citric acid cycle and he received novel prize by it.


In Japan, Mr. Shichiro Akiya who is doctor of pharmacy (ex. Tokyo university professor) is famous for research of citric acid.

(1)During WWⅡ, they tried to add citric acid to soybean paste to prevent mold. It worked for not only mold prevention, but also decreasing of crew’s fatigue. Mr. Akiya knew that crew’s health condition was improved significantly and they could endure a long drive.

(2)Mr. Akiya drink citric acid by himself and figured out the fact that amount of lactic acid in urine decreased.


Citric acid promotes citric acid cycle action and decreases lactic acid generation which is fatigue. (Pharmaceutical journal 76111~115 [1956])

From that, he proved experimentally that citric acid have important role for fatigue recovery health promotion.


Characteristics of citric acid  

 Chemical formula


 Molar mass



White crystals

 Melting point

100°C(Monohydrate)becomes anhydrous when heated and dissolved oneself

 Decomposition point


 Solubility in water


 Acid dissociation constant pKa


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