Hydro-distillation
This method as standard method, is the simplest and cheapest method selected for essential oil extraction from plant material. In this method, the material is immersed in water and the mixture is boiled. The water and essential oil vapor are condensed to an aqueous fraction. from the condenser, distillated flows into a mechanical separator or decanter, where oil separates from water (figure 1). Plant materials must always be immersed in water during the extraction process, so evaporated water must be replaced. This method is used to extract oil from dried flowers and powders. The main problem with this process is that heat destroys unstable and heat-sensitive compounds or causes structural changes. Also, some essential oils are water-soluble and difficult to separate [4, 7, 21, 22, 23]. rose-scented geranium (Pelargonium sp.) [24], germander (Teucrium orientale) [25] and thyme (Thymus vulgaris L.) [26] were extracted by hydro-distillation and their efficiency were compared.