Influence of hydrodistillation rate and hydromodule on chemical composition of Juniperus communis L. essential oil
Authors: Pavicevic Vladimir , Radovic Marko , Milojevic Svetomir , Markovic Miljana , Ristic Mihailo , Povrenovic Dragan 
Published: February 2016

Essential oils are aromatic, volatile, complex mixtures of various compounds,
mainly hydrocarbons (monoterpene and sesquiterpene) and some oxygenated
hydrocarbons. Juniper berry essential oil has wide application and high
commercial value due to its considerable antimicrobial activities. It is used
in medicine, food, cosmetic and pharmaceutical industry and veterinary
medicine. Generally, it is obtained by hydrodistillation, technique for the
extraction of substances which do not mix or mix very poorly with water and
are unstable at their boiling temperatures. It provides high quality of
essential oil and also represents a relatively simple, safe and
environmentally friendly process. The variations in the chemical composition
of the essential oil obtained from juniper berries at various distillation
rates (3, 6 and 8 ml/min) and various mass ratio juniper berries?water
(hydromodules - 1:3, 1:4 and 1:5) are presented in this paper. It is
important to emphasize that the variations made influence only in
quantitative (mass %), but not in qualitative chemical composition (no
differences, same 58 components were detected in all experiments). To reflect
those effects, only 23 identified components with the content higher than 0.5
mass % were selected, constituted 95?96 mass % of the essential oils. The
major constituents of the essential oils were monoterpenes (67.39?71.00 mass
%), followed by sesquiterpenes (21.64?24.54 mass %), while the oxygenated
monoterpene (1.54?2.42 mas. %) and oxygenated sesquiterpenes (0.89?1.46 mass
%) were much less present. According to volatility, the high volatile
(boiling point 153?167?C) components are the main constituents of the
essential oils (61.69?63.81 mass %), followed by the low volatile (boiling
point 252?288oC) components (22.57?26.04 mass %), and the least present
medium volatile (boiling point 173?212?C) components (7.24?9.61 mass %). The
variations in the mass content of the essential oil at various distillation
rates showed clear general trends for all hydromodules (with exceptions at
some components). With the increasing of distillation rate, mass % of high
and medium volatile components decreased, while mass % of low volatile
components increased. This is caused by higher extraction of low volatile
components at high distillation rate, which resulted the increasing of their
mass %. The variations in the mass composition of the essential oil at
various hydromodules showed less expressive trends for all distillation
rates. That means it has much less influence on the mass composition than the
variation of distillation rate. Therefore, experiments at various
distillation rates should be continued in combination with the fractionation
of the essential oil by simultaneous hydrodistillation and rectification,
including the effects of preparation procedures of juniper berries and
defining of optimal energy consumption, i.e. optimal time period of
hydrodistillation.