Biosynthesis of ethyl caproate and other short ethyl esters catalyzed by cutinase in organic solvent

Abstract

The main objective of this work was to study the enzymatic synthesis of short chain ethyl esters, a group of relevant aroma molecules, by Fusarium solani pisi cutinase in an organic solvent media (iso-octane), and to assess the influence of different parameters on the reaction yield. Cutinase displayed high initial esterification rates in iso-octane. which amounted to 1.15 mu mol min(-1) mg(-1) for ethyl butyrate (C-4 acid chain) and 1.06 mu mol min(-1) mg(-1) for ethyl valerate (C-S acid chain). High product yields, 84% for ethyl butyrate and 96% for ethyl valerate, were observed after 6 h of reaction, for an initial equimolar concentration of substrates (0.1 M). The highest product yield (97%) was observed for ethyl caproate (C-6) synthesis, a compound which is a part of natural apple and pineapple flavour, for an alcohol:acid molar ratio of 2 (0.2 M ethanol concentration). Cutinase affinity for short chain length carboxylic acids (C-4-C-6) in ester synthesis in iso-octane confirmed previous observations in reversed micellar system.