Essential oils are the fragrant, highly concentrated natural constituents that are extracted from botanical sources. They have a characteristic odour and contain the healing power of the plant from which it was extracted.
An essential oil may contain hundreds of different organic constituents which unite in delicate balance. It is this exquisite natural balance that produces the oil’s therapeutic and olfactory qualities, which is why it is so critical to use 100% pure essential oils.
The Unique Qualities of Pure Essential Oils:
- They may be applied to the skin to work both on and within the body.
- They may provide direct therapeutic benefits to the mind and emotions through inhalation.
- They are highly concentrated so a small amount goes a long way.
- Many contain antiseptic, antifungal, antiviral and antibacterial properties.
How Oils Are Extracted
Of a variety of methods used to extract pure essential oils from plants, the most significant are steam distillation, expression and extraction. Recovering the oil is a painstaking process and the yield minute. Huge volumes of plants are needed. For instance, it requires some 2000kg of fresh lavender flowers, between 2000 and 3000kg of rose petals and 3000 lemons to produce a single kilo of lavender rose and lemon essential oils.
The most common and widely-used method of extraction is steam distillation. The process of how steam distillation works is shown in the following:
1. Plant material is placed inside the distillation vat known as the ‘retort’.
2. Steam generated in an external boiler is passed up through a perforated floor in the retort and vapourises the oil.
3. The mixture of oil and water vapour is passed via the vapour tube to the top of the condenser.
4. The vapour mixture passes through a bundle of tubes cooled in a jacket of water.
5. The water and oil vapours return to their liquid state and flow into the separator below.
6. The generally lighter essential oil rises to the top and floats on the water. The oil is drawn off from time to time as the layer builds.
7. The water, which contains traces of slightly soluble fractions of the oil, is drawn off continuously from the bottom of the separator – this is the ‘hydrolat’. Hundreds of litres of hydrolat are produced in the production of one litre of essential oil!
This form of extraction applies only to citrus oils. The peel of citrus fruits has oil glands containing globules of essential oils. These are squeezed from the peel after the pulp has been separated. Traditionally performed by hand, the process is now mechanised.
Extraction is used mainly for the more delicate flowers, such as jasmine, orange flowers and tuberose. The final products of extraction are called absolutes, concretes and resinoids. The oldest method and the process is similar, are:
Maceration – soaking the plant materials in the vegetable base oil.
Enfleurage – placing flower petals on purified animal fats.
This process is sometimes still used in the South of France for the extraction of jasmine and tuberose. The resulting pomade goes through a process called defleurage, in which the aromatic substances are washed out with alcohol and then purified. Essential oils are extracted in this way tend to be of a superior quality to those obtained by distillation and are usually more expensive.
This is a complex process, in which flower petals are placed in a sealed container and carefully submerged in a liquid solvent, usually petroleum ether. The solvent gradually dissolves the essential oils from the petals. The solution is then collected and the solvent gently distilled off.
On separation, the residual is a semisolid aromatic material called a concrete, which contains some of the plants natural waxes along with other non-aromatic materials.
This concrete is shaken with alcohol; and when the alcohol is distilled off, a coloured liquid – the absolute – remains. Resinoids, similar to concretes, are extractions from tree resins.
When essential oils are used for therapeutic purposes it is generally better to avoid oils that have been extracted by solvents, because traces of the solvents may remain. The method is better suited to products used in perfumery.