Preservatives

Preservatives work by inhibiting, retarding or outright arresting the processes -- fermentation, acidification, general decomposition -- that microbial growth causes in food. Several distinct chemical families are used: organic acids such as benzoic acid and sorbic acid (and their salts) are potent inhibitors against a broad range of fungi, yeasts and bacteria; alkyl esters of hydroxybenzoic acid perform especially well under less acidic conditions than the parent acid would need; acetic acid is the workhorse preservative for pickles and preserved vegetables; sodium metabisulphite specifically preserves fresh vegetables and fruit; and sucrose esters of palmitic and stearic acid do double duty as both preservative and emulsifier. Chemistry is not the only tool available, though -- the unit is careful to note that physical preservation methods matter ju …