Sodium benzoate can act as a food preservative. It is most widely used in acidic foods such as salad dressings (for example acetic acid in vinegar), carbonated drinks (carbonic acid), jams and fruit juices (citric acid), pickles (acetic acid), condiments, and frozen yogurt toppings. It is also used as a preservative in medicines and cosmetics.[6][7] 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.[8] Sodium benzoate is also allowed as an animal food additive at up to 0.1%, per the Association of American Feed Control Officials.[9]
Sodium benzoate has been replaced by potassium sorbate in the majority of soft drinks in the United Kingdom.[10]
Sodium benzoate is used as a treatment for urea cycle disorders due to its ability to bind amino acids.[11][12] 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.[13][14][15] Total Positive and Negative Syndrome Scale scores dropped by 21% compared to placebo.
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.[21][22]
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,[23] which inhibits the growth and survival of microorganisms that cause food spoilage.
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 ppbMaximum Contaminant Level set by the Environmental Protection Agency for drinking water.[30] Most of the beverages that tested above the limit have been reformulated and subsequently tested below the safety limit.[30] 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"[31]) so the observation about beverages applies to pepper sauces containing sodium benzoate, like Texas Pete.
ADHD and hyperactivity
Research published, including in 2007 for the UK's Food Standards Agency (FSA) suggests that certain artificial colors, 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.[32][33][34] 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.[34] The report's author, Jim Stevenson from Southampton University, said: "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. . . . Many other influences are at work but this at least is one a child can avoid."[34]
^del Olmo A, Calzada J, Nuñez M (20 November 2015). "Benzoic acid and its derivatives as naturally occurring compounds in foods and as additives: Uses, exposure, and controversy". Critical Reviews in Food Science and Nutrition. 57 (14): 3084–3103. doi:10.1080/10408398.2015.1087964. PMID26587821. S2CID205692543.
^Saltmarsh M (15 March 2015). "Recent trends in the use of food additives in the United Kingdom". Journal of the Science of Food and Agriculture. 95 (4): 649–652. Bibcode:2015JSFA...95..649S. doi:10.1002/jsfa.6715. ISSN1097-0010. PMID24789520. ... the preservative used in the study, sodium benzoate, has been replaced by potassium sorbate in the majority of soft drinks.
^Wilcken B (2004). "Problems in the management of urea cycle disorders". Molecular Genetics and Metabolism. 81 (Suppl 1): S86–91. doi:10.1016/j.ymgme.2003.10.016. PMID15050980.
^ abCosmetic 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. doi:10.1080/10915810152630729. PMID11766131. S2CID13639993.
^Bedford PG, Clarke EG (January 1972). "Experimental benzoic acid poisoning in the cat". Vet. Rec. 90 (3): 53–8. doi:10.1136/vr.90.3.53 (inactive 1 November 2024). PMID4672555. S2CID2553612.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
^"butyrate-CoA ligase". BRENDA. Technische Universität Braunschweig. Retrieved 7 May 2014. Substrate/Product
^"glycine N-acyltransferase". BRENDA. Technische Universität Braunschweig. Retrieved 7 May 2014. Substrate/Product
Kubota K, Ishizaki T (1991). "Dose-dependent pharmacokinetics of benzoic acid following oral administration of sodium benzoate to humans". Eur. J. Clin. Pharmacol. 41 (4): 363–8. doi:10.1007/BF00314969. PMID1804654. S2CID8196430. Although the maximum rate of biotransformation of benzoic acid to hippuric acid varied between 17.2 and 28.8 mg.kg-1.h-1 among the six individuals, the mean value (23.0 mg.kg-1.h-1) was fairly close to that provided by daily maximum dose (0.5 g.kg-1.day-1) recommended in the treatment of hyperammonaemia in patients with inborn errors of ureagenesis