Benzoate

Benzoate refers to the benzoate ion, C6H5COO−, the conjugate base of benzoic acid, as well as salts and esters derived from benzoic acid. In water, benzoic acid has a pKa of about 4.2, so benzoate predominates at neutral and basic pH values; many benzoate salts are readily soluble. Common benzoate salts include sodium benzoate, potassium benzoate, and calcium benzoate. In organic chemistry, esters of benzoic acid are called benzoates, such as methyl benzoate and ethyl benzoate, which are used as flavorings and fragrances.

Applications include food preservation, cosmetics, pharmaceuticals, and as intermediates in organic synthesis. Sodium benzoate is widely used as a preservative in acidic foods and beverages for antimicrobial effects. Benzoates and benzoate esters are also used in flavorings and perfumery.

Occurrence and metabolism: Benzoate occurs naturally in some fruits and spices; many microorganisms can metabolize benzoate as a carbon source via aerobic and anaerobic pathways, eventually feeding into central metabolism as benzoyl-CoA.

Safety and regulation: Regulatory agencies permit benzoate usage at specified levels in foods and cosmetics; most people tolerate it well, but rare allergic reactions occur. In some beverages, sodium benzoate can react with ascorbic acid and metal ions to form benzene under certain conditions; manufacturers and regulators monitor and limit such risks.