Lactones

Lactones are heterocyclic compounds — intramolecular cyclic esters formed when a hydroxy carboxylic acid condenses with itself, eliminating water. In food they appear both as additives, such as the acidulant and firming agent glucono-δ-lactone (E575, used in tofu coagulation and meat products), and as natural aroma compounds: γ-decalactone and δ-decalactone give peachy notes, whisky lactone (oak lactone) gives coconut-woody notes to barrel-aged spirits, and coumarin gives sweet-hay aroma. Their ring structure makes many of them potent, characteristic flavour notes at trace levels; flavourists use them widely, within regulated limits (coumarin is restricted).