Biotechnological production of flavour-active lactones

Abstract

Biotechnology lends itself to the production of natural flavour materials, which can either be obtained as complex mixtures or pure, individual flavour components. Examples of the latter category are acids, alcohols, esters, aldehydes, ketones and lactones. Biotechnological processes are reviewed which can be used to produce those γ- and δ-lactones which are important to the flavour industry. Emphasis is placed upon fermentative processes using microorganisms capable of performing β-oxidative degradation reactions. The preferred substrates in this type of biotransformation are hydroxy fatty acids which can themselves be obtained enzymatically or extracted from natural sources. Certain microorganisms are capable of hydroxylating fatty acids, thereby giving rise to the immediate precursors of γ- and δ-lactones. The intramolecular esterification of hydroxy fatty acids can be catalysed by certain lipases. The lipase from Candida antarctica is also capable of converting some cyclic ketones to the corresponding lactones via the Baeyer-Villiger reaction.