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.