Aromatherapy uses plant-derived essential oils to gently stimulate the natural healing action of both body and mind. Different parts of a plant are used for oil extraction depending upon their aromatic properties. There are a number of methods used to extract oils from plants. The method used depends primarily on the characteristics of the plant itself.
The first time I witnessed essential oils going through the steam distillation process, it was a feast for all of my senses. Hot steam was forced through copious amounts of aromatic plant matter and then travelled through cooling tubes that condensed the steam and captured the distillate.
Scented water (hydrosol) and the precious essential oil then passed into a large glass beaker. Most essential oils (also known as volatile or ethereal oil) weigh less than water; therefore, they float on top of the water solution until they naturally separate. At this point the essential oil floating on the top was drawn off until we had a vial of pure, unadulterated essential oil and a large bucket of beautiful aromatic hydrosol.
The most common and economical of the extraction methods, steam distillation is used because it generally yields more essential oil from botanicals such as herbs. There are a number of other methods used to extract oils from plants. The method used depends primarily on the characteristics of the plant itself.
This is one of the more common methods of distillation. The aromatic botanicals are simply immersed in water and brought to a boil. The essential oils are then carried via steam to be captured in the cooling condenser. Hydro distillation accommodates any type of botanical, including flowers, fruits, gums, leaves, nuts, roots, seeds, sawdust, and wood chips.
Expression or Cold Pressed
This extraction method is used exclusively with citrus fruits because the essential oils are located in little sacs just under the surface of the peel and simply need to be pressed out. Oils extracted by expression are the most volatile and evaporate quickly.
This method involves the extraction of oils with the use of solvents. Hydrocarbon solvents yield a resinoid, while alcohol solvents yield absolutes. Both solvent methods are commonly used in the perfume industry to extract the aroma of delicate flowers. The solvent is poured over the flowers and the essential oil is captured in the solution.
The solution is then processed in order to be palatable to the consumer. This method is used with many delicate flowers such as the rose because they don’t yield a satisfactory amount of oil by the steam distillation method. The solvents are never completely eliminated; therefore, oils processed this way should be used sparingly and with care for therapeutic purposes.
This rather new and complicated technology uses carbon dioxide at high pressures and extremely low temperatures to capture the essential oil from the plant. The oil obtained is colourless, pure, and stable with no residue of CO2 remaining.
Used since the 19th century, enfleurage is one of the oldest methods of essential oil extraction. Traditionally, delicate flowers such as jasmine or tuberose were placed on clean fat; over many days, the fragrance would be transferred to the fat oil. Pomades, salves, and cremes were made from the fat.
How are Hydrosols Used?
Hydrosols are the pure, water-based solutions created when essential oils are steam distilled. Hydrosols are often called floral water but can also be derived from all plant parts including the flowers, leaves, stems, and roots. The word hydrosol is derived from the two root words hydro meaning water and sol meaning solution.
Hydrosols contain water-soluble essential oil molecules that were flowing through the plant cells when the plant was collected, as well as constituents that are not present in the essential oil. They are potent, yet more subtle than essential oils.
Hydrosols may be applied directly to the skin as a spray mist, a compress, or in a soak, either neat or diluted with purified water or other appropriate liquid. They are also used as ingredients in cremes, lotions, shampoos, masks, and other personal care products.
Where the Oil Comes From
Different parts of a plant are used for oil extraction depending upon their aromatic properties.
Here are a few examples.
|Type of Oil||Parts Used|
|lemon grass oil||grasses|
|ylang ylang oil||tree blossoms|