Enzymatic modification of enriched lemon oil in a solvent-free reaction medium: Bioconversion yield and product profile

Abstract

The present study focused on the modification of the chemical profile of selected terpenes and enriched lemon essential oil through lipase-catalyzed transesterification with the aim to broaden their applications. The reaction capacities of 3 terpenes (eugenol, thymol, geraniol) with vinyl esters (vinyl acetate, vinyl propionate) and commercial lipases from Candida rugosa and Candida antarctica (Novozym® 435) were studied. Phenolic terpenes were not detected to have participated in the transesterification reaction and were therefore not modified, which could be attributed to the position of the hydroxyl group on their phenyl moiety. Geraniol was successfully modified in toluene and a solvent-free medium utilizing lemon oil as the reaction medium, with bioconversion yields as high as 100% and 88%, respectively. These findings revealed the efficiency of solvent-free modification of terpene alcohols in essential oils. This method could, therefore, be considered to modify essential oils to be used as functional ingredients in food products. • Lipase from Candida rugosa and Novozym® 435 can modify geraniol with vinyl esters. • Novozym® 435 exhibited the highest acylation yields (41–100%). • Geraniol can undergo solvent-free transesterification by Novozym® 435 in lemon oil. • The solvent-free reaction reached 89% acylation yield in 15 h with vinyl esters. • Enzymatic modification of essential oils can broaden their applications.