Potassium benzoate, the potassium salt of benzoic acid, is a food preservative that inhibits the growth of mold, yeast and some bacteria. It works best in low-pH products, below 4.5, where it exists as benzoic acid.

Acidic foods and beverages such as fruit juice (citric acid), sparkling drinks (carbonic acid), soft drinks (phosphoric acid), and pickles (vinegar) are preserved with potassium benzoate.

It is approved for use in most countries including Canada, the U.S., and the EU, where it is designated by the E number E212. In the EU, it is not recommended for consumption by children.[1]

Sodium benzoate is used as a preservative. It is not bactericidal, only bacteriostatic. It has fungistatic activity. It is effective only in acidic conditions (pH< 3.6) making its use most prevalent in foods such as preserves, salad dressings (vinegar), carbonated drinks (carbonic acid), jams (citric acid), fruit juices (citric acid), pickles (vinegar), and Chinese food sauces (soy, mustard, and duck).[citation needed] It is also found in alcohol-based mouthwash and silver polish. Sodium benzoate is used in many soft drinks and can be identified on the label of the bottle or can as 'sodium benzoate' or E211. The taste of sodium benzoate cannot be detected by around 25 percent of the population, but for those who can taste the chemical, it tends to be perceived as sweet, salty, or sometimes bitter.