Sodium benzoate also known as benzoate of soda is the sodium salt of benzoic acid, widely used as a food preservative (with an E number of E211) and a pickling agent. It appears as a white crystalline chemical with the chemical formula .
Production
Sodium benzoate is commonly produced by the neutralization of
sodium hydroxide (NaOH) with
benzoic acid (),
which is itself produced commercially by partial oxidation of
toluene with
oxygen.
Reactions
Sodium benzoate can be
Decarboxylation with strong base and heat, yielding
benzene:
Natural occurrence
Sodium benzoate is not a naturally occurring substance. However many foods are natural sources of benzoic acid, its salts, and its
.
and
can be rich sources, particularly berries such as
cranberry and
bilberry. Other sources include
seafood, such as
, and
.
Uses
As a preservative
Sodium benzoate can act as a food preservative. It is most widely used in acidic foods such as
(for example
acetic acid in
vinegar),
Soft drink (
carbonic acid),
Fruit preserves and
Juice (
citric acid),
pickling (
acetic acid),
, and
frozen yogurt toppings. It is also used as a preservative in medicines and cosmetics.
[ National Library of Medicine
] Under these conditions it is converted into
benzoic acid (E210), which is bacteriostatic and
fungistatic. Benzoic acid is generally not used directly due to its poor water solubility.
Concentration as a food preservative is limited by the FDA in the U.S. to 0.1% by weight.
Sodium benzoate is also allowed as an animal food additive at up to 0.1%, per the Association of American Feed Control Officials.
Sodium benzoate has been replaced by potassium sorbate in the majority of soft drinks in the
United Kingdom.
In the 19th century, sodium benzoate as a food ingredient was investigated by Harvey W. Wiley with his 'Poison Squad' as part of the US Department of Agriculture. This led to the 1906 Pure Food and Drug Act, a key event in the early history of food regulation in the United States.
In pharmaceuticals
Sodium benzoate is used as a treatment for urea cycle disorders due to its ability to bind amino acids.
This leads to excretion of these amino acids and a decrease in ammonia levels. Recent research shows that sodium benzoate may be beneficial as an add-on therapy (1 gram/day) in
schizophrenia.
[ Add-on Treatment of Benzoate for Schizophrenia A Randomized, Double-blind, Placebo-Controlled Trial of d-Amino Acid Oxidase Inhibitor December 2013][ Mental Health Research Institute Staff Publications, University of Michigan. Mental Health Research Institute] Total Positive and Negative Syndrome Scale scores dropped by 21% compared to placebo.
Sodium benzoate, along with phenylbutyrate, is used to treat hyperammonemia.
Sodium benzoate, along with caffeine, is used to treat postdural puncture headache, respiratory depression associated with overdosage of narcotics,[ mayoclinic.org, Caffeine And Sodium Benzoate (Injection Route)] and has been used experimentally with ergotamine to treat vascular headache.
Other uses
Sodium benzoate 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.
Mechanism of food preservation
The mechanism starts with the absorption of benzoic acid into the cell. If the
intracellular pH falls to 5 or lower, the anaerobic fermentation of
glucose through phosphofructokinase decreases sharply,
which inhibits the growth and survival of microorganisms that cause food spoilage.
Health and safety
In the
United States, sodium benzoate is designated as generally recognized as safe (GRAS) by the Food and Drug Administration.
The International Programme on Chemical Safety found no adverse effects in rats 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.
The human body rapidly clears sodium benzoate by combining it with glycine to form hippuric acid which is then excreted.[ Substrate/Product] which is then metabolized by glycine N-acyltransferase into hippuric acid.[ Substrate/Product]
Association with benzene in soft drinks and pepper sauces
In combination with
ascorbic acid (vitamin C, E300), sodium benzoate and potassium benzoate may form
benzene. In 2006, the Food and Drug Administration tested 100 beverages available in the United States that contained both ascorbic acid and benzoate. Four had benzene levels that were above the 5 ppb Maximum Contaminant Level set by the Environmental Protection Agency for drinking water.
Most of the beverages that tested above the limit have been reformulated and subsequently tested below the safety limit.
[ Heat, light and shelf life can increase the rate at which benzene is formed. Hot peppers naturally contain vitamin C ("nearly as much as in one orange"]
ADHD and hyperactivity
Research published, including in 2007 for the UK's Food Standards Agency (FSA) suggests that certain , when paired with sodium benzoate, may be linked to hyperactive behavior and other ADHD symptoms. The results were inconsistent regarding sodium benzoate, so the FSA recommended further study.[ Food Standards Agency issues revised advice on certain artificial colours 6 September 2007][ Food Colorings and Hyperactivity "Myomancy" 7 September 2007][ Agency revises advice on certain artificial colours , Food Standards Agency, 11 September 2007] The Food Standards Agency concluded that the observed increases in hyperactive behavior, if real, were more likely to be linked to the artificial colors than to sodium benzoate.
Compendial status
-
British Pharmacopoeia
-
European Pharmacopoeia
-
Food Chemicals Codex
-
Japanese Pharmacopoeia
-
United States Pharmacopeia
See also
-
Acceptable daily intake
-
List of investigational antipsychotics
-
Potassium benzoate
External links
.
