Sodium benzoate

Sodium benzoate has the chemical formula Na C6H5C O2; it is a widely used food preservative, with  E number E211. 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.

Uses
Sodium benzoate is a preservative. It is bacteriostatic and fungistatic under acidic conditions. It is most widely used in acidic foods such as salad dressings (vinegar), carbonated drinks (carbonic acid), jams and fruit juices (citric acid), pickles (vinegar), and condiments. It is also used as a preservative in medicines and cosmetics. As a food additive, sodium benzoate has the E number E211.

It is also used in fireworks as a fuel in whistle mix, a powder that emits a whistling noise when compressed into a tube and ignited. The fuel is also one of the fastest burning rocket fuels and provides a lot of thrust and smoke. It does have its downsides: there is a high danger of explosion when the fuel is sharply compressed because of the fuel's sensitivity to impact.

Sodium benzoate is produced by the neutralization of benzoic acid with sodium hydroxide. Benzoic acid is detectable at low levels in cranberries, prunes, greengage plums, cinnamon, ripe cloves, and apples. Though benzoic acid is a more effective preservative, sodium benzoate is more commonly used as a food additive because benzoic acid does not dissolve well in water. Concentration as a preservative is limited by the FDA in the U.S. to 0.1% by weight. The International Programme on Chemical Safety found no adverse effects in humans at doses of 647–825 mg/kg of body weight per day.

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

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%.

Safety and health
In combination with ascorbic acid (vitamin C, E300), sodium benzoate and potassium benzoate form benzene, a known carcinogen. However, in most beverages that contain both, the benzene levels are below those considered dangerous for consumption. Heat, light and shelf life can affect the rate at which benzene is formed.

Professor Peter W. 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. Mitochondria consume oxygen to generate ATP, the body's energy currency. If they are damaged due to disease, the cell malfunctions and may enter apoptosis.

Hyperactivity
Research published in 2007 for the UK's Food Standards Agency (FSA) suggests that certain artificial colours, when paired with sodium benzoate (E211) may be linked to hyperactive behaviour. The results were inconsistent regarding sodium benzoate, so the FSA recommended further study.

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: Mix B:
 * Sunset yellow (E110)
 * Tartrazine (E102)
 * Carmoisine (E122)
 * Ponceau 4R (E124)
 * Sodium benzoate (E211)
 * 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.

On 10 April 2008, the Foods Standard Agency called for a voluntary removal of the colours (but not sodium benzoate) by 2009. In addition, it recommended that there should be action to phase them out in food and drink in the European Union (EU) over a specified period.

In response to consumer insistence on a more natural product and E211's links to DNA damage and ADHD, the Coca Cola Company is in the process of phasing Sodium Benzoate out of Diet Coke. The company has stated that it plans to remove E211 from its other products — including Sprite, Fanta, and Oasis — as soon as a satisfactory alternative is discovered.

Compendial status

 * British Pharmacopoeia
 * Food Chemical Codex
 * European Pharmacopoeia
 * Japanese Pharmacopoeia
 * United States Pharmacopeia 29