7th June 2008. Metabolism.

Citric Acid is one of the most important organic acids. It is a primary metabolic product and is formed from a series of chemical reactions that unify Carbohydrates, fats and proteins.

It is one of the most indispensable and widely used organic acids and occur in citrus fruits, animal fluids and tissues.

Citrus Fruits.

Citrus Fruits.

The vital place of Citric Acid in Metabolism was discovered by Sir Hans Krebs in whose honour a Blue Plaque was unveiled Today in 2008, at his home 27, Abberbury Road, Iffley.


The Kreb’s or Citric Acid Cycle is used by all aerobic organisms to convert food into energy via a series of 8 steps in the presence of oxygen: Cell Respiration.

This diverting of chemical energy in food leads to life-sustaining processes and the waste of CO2 and water.

These chemical reactions are the source of 2/3rds of our food derived energy.

The stages before the Citric/Kreb’s Cycle begins is with our food intake, then to the Glycolysis Process,(1) by which Glucose is broken down, resulting in Pyruvic Acid (Pyruvate)-via oxidation- which now enters cellular Mitochondria.(2)

Finally the Acetyl-CoA molecule conveys Carbon to the Kreb’s Cycle before converting to CO2 and Energy.

Pyruvate forms in the body when food is converted into energy, is an Anti-Oxidant and found in red apples, cheese, red wine and dark beer. It used as a diet supplement as it cranks up the metabolic rate from the minimum amount necessary to burn up the calories.

So the most complex of microbiology can be reduced to the matter of slimming!

(1) Glycolysis takes place with or without oxygen and is when Glucose is partially broken down to provide usable energy for bodily cells. It was the first metabolic pathway discovered.

(2) Pyruvic Acid is made from Glucose via Glycolysis. Glucose constitutes 70% of plant material. Pyruvic Acid  is a weak acid and its conjugate base is Pyruvate.


One who was working in the same field and acknowledged by Krebs was Donald Nicholson (16.1.1916-12.5.2012) and who despite an indifferent academic career, just scraping a chemistry degree at Huddersfield College, produced the first integrated map of metabolic pathways in the 1940.s.

He also demonstrated how  Glycolysis converts Glucose to Pyruvate.

Ref: inwebarticles.com/citric-acid/Pic Image.

Ref: chemwiki.ucdavis.edu/analytical_chemistry.

Ref: deliciousliving.com/pyruvate.

Ref: chemiwiki.ucdavis.educ/biol_chem/metab/K.C.

Ref: oxfordshireblueplaques/Pic Image.



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About colindunkerley

My name is Colin Dunkerley who having spent two years in the Royal Army Pay Corps ploughed many a barren industrial furrow until drawn to the 'chalk-face' as a teacher, now retired. I have spent the last 15 years researching all aspects of life in Britain since Roman times.

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