Essential oil extraction is the way in which volatile compounds are removed from plants to create the oils we use in aromatherapy. A variety of methods are used for this purpose. We will discuss some of these here so that you can get a sense of how essential oils make there way into the tiny bottles you keep in your cupboard.
Most pure essential oils are extracted by a distillation process. Techniques differ but they all use water heated to form steam. This steam contains most of the molecules of volatile compounds. The steam is chilled by means of a condenser. and what remains is collected. The oil floats to the surface of the water and can be separated. Most essential oil extraction is done this way, at least when it come to oils of purest quality.
Essential oil extraction is also done via true steam distillation. This process makes use of a source of steam which channels the steam into a distillation unit. Often this is done under high pressure. After the steam as passed through the plant material it collects in a condenser. The steam passes through the aromatic material, and exits into the condenser.
In the Hydro-distillation method of essential oil extraction plant material is soaked in water and the resulting mixture produces steam. The steam contains the volatile compounds. This is a cheap and easy method but not always reliable.
In the water and steam distillation method of essential oil extraction the process is similar to the way a kitchen steamer basket works to cook food. Here the plant materials are held in a basket over boiling water. The steam passes over the plan materials. This kind of essential oil extraction is the most effective for leafy materials. It is not generally used for roots, bark and seeds.
Solvent extraction is used for very delicate plant materials like Jasmine, Linden Blossom,etc. These materials do not last under the harsh conditions of the distillation methods of essential oil extraction. So instead, a method called solvent extraction is used. In this method of extracting essential oils an extracting unit is piled perforated trays of plant material. These are washed many times with a hexane. The hexane acts as a solvent and dissolves the essential components of the plant.
Carbon dioxide essential oil extraction is used to yield compounds from plants that do not release oils such as rose hip seed and calendula. Cold pressing is a method of essential oil extraction that is often used for releasing the aromatic compounds from citrus plants like orange and lemon. Machines press down on the rind and collect the oil that is expressed.
The use of Florasols/Phytols is a new method of essential oil extraction. In this case oils are extracted using harmless gaseous solvents at low temperatures. This means that heat does not destroy the therapeutic components of the plant materials. Presently such oils are only distributed by The Essential Oil Company. However it is likely that oil extracted using such methods will become more widely available in the near future.
