Microwave-assisted hydrodistillation of juniper berry essential oil: kinetic modeling and chemical composition

Abstract

BACKGROUNDMicrowave-assisted hydrodistillation (MAHD) has widely been used to isolate essential oil from various plant materials, but it has not been applied yet to extract essential oil from juniper berries. The main goals of the present work were to establish a model describing the extraction kinetics and the chemical composition of the essential oil obtained. RESULTSA lower final essential oil yield from juniper berries was obtained by MAHD than by conventional hydrodistillation (HD). No significant differences in chemical compositions of the essential oils extracted by the two techniques were observed. The mechanism of both processes was the same and included fast (washing) and slow (diffusion) distillation of essential oil that occurred simultaneously. CONCLUSIONThe kinetic model involving simultaneous washing and diffusion of essential oil was verified for various plant materials (areal parts of savory and thyme, fennel seeds and juniper berries) for both MAHD and HD that indicated its general importance. For the first time, the kinetic models of MAHD and HD were compared. Knowledge of the juniper berry essential oil yield and the extraction kinetics is of importance from the technological and economics points of view, while the chemical composition determines its use.