What is citric acid
Citric acid is an organic acid which is contained in plentiful amounts in plums and lemons. Citric acid atributes to the acidic component of these fruits.
In 1937, Mr. H.A. Krebs, a biochemist from the UK, first clarified the mechanism of how humans produce energy from food to sustain life, that is, the actual state of vivo metabolism.
He discovered that citric acid played the most critical role in regualtion of metabolism. Krebs’s cycle or the citric acid cycle received novel prize, gaining widespread esteem for the discovery.
In Japan, Mr. Shichiro Akiya who is doctor of pharmacy (ex. Tokyo university professor) is famous for research of citric acid.
(1)During WWⅡ, citric acid was added to miso paste as an attempt to prevent mold while in submarines. It worked not only by preventing mold, but also noticibly decreased the crew’s fatigue improving their health condition and allowing them to endure a long dives.
(2)Mr. Akiya drank citric acid 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 contributes to fatigue. (Pharmaceutical journal 1956 Vol. 76 2nd p.111~115)
From that, he proved experimentally that citric acid has an important role for fatigue recovery and improving health.
Characteristics of citric acid
|
Chemical formula |
C6H8O7・H2O |
|
Molar mass |
210.14g/mol（Monohydrate） |
|
Appearance |
White crystals |
|
Melting point |
100°C（Monohydrate）becomes anhydrous when heated and dissolved oneself |
|
Decomposition point |
175°C |
|
Solubility in water |
133g/100mL（20°C） |
|
Acid dissociation constant pKa |
pKa1=3.15 |