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Sodium benzoate

Sodium benzoate
IUPAC name Sodium benzoate
Other names E211, benzoate of soda
CAS number 532-32-1
SMILES O=C([O-])C1=CC=CC=C1.[Na+]
Molecular formula NaC6H5CO2
Molar mass 144.11 g mol−1
Density 1.44 g cm−3
Melting point

>300 °C

Boiling point


Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Sodium benzoate (E211), also called benzoate of soda, has chemical formula C6H5COONa. It is the sodium salt of benzoic acid and exists in this form when dissolved in water. It can be produced by reacting sodium hydroxide with benzoic acid.



Sodium benzoate is used as a preservative. It is not bactericidal, only bacteriostatic. It has fungistatic activity. It is effective only in acidic conditions (pH< 3.6) making its use most prevalent in foods such as preserves, salad dressings (vinegar), carbonated drinks (carbonic acid), jams (citric acid), fruit juices (citric acid), pickles (vinegar), and Chinese food sauces (soy, mustard, and duck).[citation needed] It is also found in alcohol-based mouthwash and silver polish. Sodium benzoate is used in many soft drinks and can be identified on the label of the bottle or can as 'sodium benzoate' or E211. The taste of sodium benzoate cannot be detected by around 25 percent of the population, but for those who can taste the chemical, it tends to be perceived as sweet, salty, or sometimes bitter.

It is also used in fireworks as a fuel in whistle mix, a powder which imparts a whistling noise when compressed into a tube and ignited.

It is found naturally in cranberries, prunes, greengage plums, cinnamon, ripe cloves, and apples. Concentration as a preservative is limited by the FDA in the U.S. to 0.1% by weight though organically-grown cranberries and prunes can conceivably contain levels exceeding this limit. The International Programme on Chemical Safety found no adverse effects in humans at doses of 647-825 mg/kg of body weight per day.[1][2]

Cats have a significantly lower tolerance against benzoic acid and its salts than rats and mice.[3] Sodium benzoate is, however, allowed as an animal food additive at up to 0.1%, according to AFCO's official publication.[4]

Mechanism of food preservation

The mechanism starts with the absorption of benzoic acid into the cell. If the intracellular pH changes to 5 or lower, the anaerobic fermentation of glucose through phosphofructokinase is decreased by 95%.[5]

Safety and health

Main article: benzene in soft drinks

In combination with ascorbic acid (vitamin C, E300), sodium benzoate and potassium benzoate "may" form benzene[6], a known carcinogen. Heat, light and shelf life can affect the rate at which benzene is formed.

Professor Peter Piper of the University of Sheffield claims that sodium benzoate by itself can damage and inactivate vital parts of DNA in a cell's mitochondria. "The mitochondria consumes the oxygen to give you energy and if you damage it - as happens in a number of diseased states - then the cell starts to malfunction very seriously. And there is a whole array of diseases that are now being tied to damage to this DNA - Parkinson's and quite a lot of neuro-degenerative diseases, but above all the whole process of aging."[7][8][9][10][11]


On 6 September 2007, the British Food Standards Agency issued revised advice on certain artificial food additives, including sodium benzoate (E211)[12][13][14].

Professor Jim Stevenson from Southampton University, and author of the report, said: "This has been a major study investigating an important area of research. The results suggest that consumption of certain mixtures of artificial food colours and sodium benzoate preservative are associated with increases in hyperactive behaviour in children.

"However, parents should not think that simply taking these additives out of food will prevent hyperactive disorders. We know that many other influences are at work but this at least is one a child can avoid."

Two mixtures of additives were tested in the research:

Mix A:

  • Sunset yellow (E110)
  • Tartrazine (E102)
  • Carmoisine (E122)
  • Ponceau 4R (E124)
  • Sodium benzoate (E211)

Mix B:

  • Sunset yellow (E110)
  • Quinoline yellow (E104)
  • Carmoisine (E122)
  • Allura red (E129)
  • Sodium benzoate (E211)

Sodium benzoate was included in both mixes, but the effects observed were not consistent. The Food Standards Agency therefore considers that, if real, the observed increases in hyperactive behaviour were more likely to be linked to one or more of the specific colours tested.


  1. ^ Concise International Chemical Assessment Document 26: BENZOIC ACID AND SODIUM BENZOATE
  2. ^ Cosmetic Ingredient Review Expert Panel Bindu Nair (2001). "Final Report on the Safety Assessment of Benzyl Alcohol, Benzoic Acid, and Sodium Benzoate". Int J Tox (20 (Suppl. 3)): 23-50.
  3. ^ Bedford PG, Clarke EG (1972). "Experimental benzoic acid poisoning in the cat". Vet Rec (90): 53-58. PMID
  4. ^ AFCO (2004). "OFFICIAL PUBLICATION": 262.
  5. ^ Krebs HA; Wiggins D, Stubbs M (1983). "Studies on the mechanism of the antifungal action of benzoate". Biochem J (214): 657-663.
  6. ^ FDA, 2006. "Data on Benzene in Soft Drinks and Other Beverages, " United States Food and Drug Administration. Accessed June 2nd at:
  7. ^ Martin Hickman Caution: Some soft drinks may seriously harm your health The Independent on Sunday 27 May 2007
  8. ^ Martin Hickman E211 Revealed: Evidence highlights new fear over drinks additive The Independent on Sunday 27 May 2007
  9. ^ Leading article: Children deserve our doubts The Independent on Sunday 27 May 2007
  10. ^ Chris Mercer Fresh health fears hit benzoate in soft drinks BeverageDaily 29 May 2007
  11. ^ Piper PW Yeast superoxide dismutase mutants reveal a pro-oxidant action of weak organic acid food preservatives Free Radic Biol Med 1999 Dec;27(11-12):1219-27
  12. ^ Food Standards Agency issues revised advice on certain artificial colours 6 September 2007
  13. ^ Food Colorings and Hyperactivity "Myomancy" 7 September 2007
  14. ^ Agency revises advice on certain artificial colours Food Standards Agency 11 September 2007
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sodium_benzoate". A list of authors is available in Wikipedia.
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