What is Sodium Benzoate?
Sodium benzoate is an antimicrobial agent, a common preservative.1 It is used in acidified food with high water activity.
It is produced by reacting benzoic acid with sodium bicarbonate, sodium carbonate, or sodium hydroxide.1
Sodium benzoate has effective antimicrobial action against yeasts, molds, food poisoning bacteria and spore-forming bacteria. It is not effective against food spoilage bacteria like clostridia or lactic acid bacteria.2
Benzoic acid penetrates microorganisms’ cell walls and interferes with their enzymatic cell structure, thereby inhibiting cell growth.2 It is the effective part of sodium benzoate, because the undissociated acid can readily enter the cell walls.2
In order to undissociate benzoic acid, the pH level needs to be lower than its pKa. The pKa of benzoic acid is 4.2. Sodium benzoate is most effective in acidified foods with pH 2.5–4.2.3 This pH level is lower than that of sorbic acid and propionic acid.3
High water activity is needed to form benzoic acid. Sodium benzoate is used in the system with high water activity because such activity is needed to form benzoic acid.
- Its usage level in most kinds of food is 0.05–-0.1%.3 It is used in acidified foods, such as carbonated beverages, fruit juices, cider, pickles, and sauerkraut.
- It is low in cost.
- Sodium chloride has a considerable synergistic effect with it.3
- When used in oil-in-water emulsions, like mayonnaise, sodium benzoate is used in combination with potassium sorbate.2 This mixture has a stronger effect against acid-producing bacteria than either of the two preservatives individually.
- Benzoic acid is ineffective against oxidation and enzymatic spoilage.2 When used in fruit products, sodium benzoate is usually combined with small quantities of sulfur dioxide or other antioxidants.2
Sodium benzoate is GRAS. It is to be used up to 0.1% in food, as regulated by the FDA in articles 21CFR184.1733 and 21CFR582.3733 in the Code of Federal Regulations.1,4 The safety of sodium benzoate at levels higher than 0.1% is unknown, because it reacts with ascorbic acid (vitamin C) with light and heat and creates benzene, the maximum allowable level of which is 5 ppb.5
- U.S. Food & Drug Administration. “21CFR184.1733 – Code of Federal Regulations Title 21.” Accessdata.fda.gov, 14 Aug. 2017, www.accessdata.fda.gov/scripts/cdrh%20/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1733.
- Luck, E., and M. Jager. “21 Benzoic Acid.” Antimicrobial Food Additives: Characteristics, Uses, Effects, 2nd ed., vol. 2, Springer, 1995, pp. 178–180.
- Furia, T. E. “Antimicrobial Food Additives.” CRC Handbook of Food Additives, 2nd ed., vol. 1, CRC Press, 1972, pp. 120–122.
- U.S. Food & Drug Administration. “21CFR582.3733 – Code of Federal Regulations Title 21.” Accessdata.fda.gov, 14 Aug. 2017, www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=582.3733.
- U.S. Food & Drug Administration. “Chemical Contaminants – Questions and Answers on the Occurrence of Benzene in Soft Drinks and Other Beverages.” Questions and Answers on the Occurrence of Benzene in Soft Drinks and Other Beverages, Center for Food Safety and Applied Nutrition, 6 July 2015, www.fda.gov/food/foodborneillnesscontaminants/chemicalcontaminants/ucm055131.htm