Essential Oil Extraction Processes explained
Essential oils are extracted from plant materials in various different ways.
The major techniques to obtain the oils are described below:
Distillation is the most common method of obtaining essential oils. Chemicals are not involved in the distillation process, which uses heat and water or steam. Hydrosols are produced as a by-product of this method, such as Rose water.
Plant materials are pressed by hand or machine to remove the essential oils. The method of is commonly used on peels of citrus fruits.
The solvent extraction method is used on plants too fragile for distillation. Chemical solvents are used to dissolve the essential oil, as well as waxes and resins, from the plant material. The solvent is then vaporized which leaves a concrete or resinoid, and the essential oils are removed through the use of pure alcohol. The alcohol is then evaporated and the absolute remains. Solvent extraction is preferred by perfumers as the oil is closest to the original plant scent, but not as much by aromatherapists due to the trace amount of solvent that may remain.
With this method, flowers are placed on layers of fat which absorb the essential oils. The essential oils are then extracted from the oil-saturated fat (the “pomade”) with the use of alcohol. The enfleurage method is more than a century old, but is no longer a commercially viable extraction method today.
Gas Extraction (CO2)
Uses nitrogen or carbon dioxide gas solvents and high pressure. Alcohol is not used in this process.
This is a newer process that involves using room temperature heat and “environmentally friendly” solvents.