Sodium benzoate is widely used as food preservative. While it is safe in small doses, having large amounts of sodium benzoate can be fatal. It is also known as sodium salt of benzoic acid. When water is added to salt of benzoic acid, we get sodium benzoate. Sodium benzoate occurs naturally too, especially in fruits like cranberries, blueberries and foods like seafood and dairy products.
There are 3 types of methods with which sodium benzoate can be prepared:
- Naphthalene and Vanadium pentoxide are oxidised to give phthalic anhydride, which in turn is decarboxylated to produce benzoic acid.
- Toluene and nitric acid react to form benzoic acid.
- Benzotrichloride is hydrolysed and then is reacted with a mineral acid to give benzoic acid.
Once benzoic acid is obtained from either of the above methods, it is dissolved using sodium hydroxide solution.
Food Industry: Sodium benzoate is a preservative. As a food additive, sodium benzoate has the E number E211. 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. Concentration as a 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%, according to AFCO's official publication.
Detergent Industry: Sodium benzoate is a preservative that has antifungal properties which kills bacteria, fungi and yeasts. It is often used in conventional and even some green cleaning furniture polishes, toilet bowl cleaners, dish washing detergent gels, carpet cleaning products, upholstery cleaners, and dishwasher cleaners.
Pharmaceutical Industry: Sodium benzoate is used as a treatment for urea cycle disorders. Recent research shows that sodium benzoate may be beneficial as an add-on therapy (1 gram/day) in schizophrenia. Total Positive and Negative Syndrome Scale scores dropped by 21% compared to placebo.
Other Applications: It is also used as a preservative in medicines and cosmetics.