Have you ever considered what it takes to extract the inviting aroma of your favorite essential oil from the plant? It’s an art and a science. Several different techniques are used for deriving essential oils, and those depend upon the plant source. Highlighted below is an overview of these extraction techniques.1,2,3
Essential Oil Extraction Methods
The most common way of extracting essential oils today is actually very similar to techniques used by ancient cultures. Distillation, specifically steam distillation, remains one of the most effective methods for extracting oils from flowers and herbs.
Steam distillation works by placing the flower or herb onto a grid material inside of a sill. The sill is then sealed and a distillation catalyst is injected. For steam distillation, steam is blown into the sill. Other catalysts include water, a combination of water and steam, or a hydro diffusion technique.
The high temperature of the steam or water causes the plant to begin breaking down. The essential oils evaporate at a much lower temperature than the plant itself and rise through a connecting pipe into a condenser. That condenser causes the vapor to cool and return to liquid form. The resulting liquid is captured in a container located below the condenser.
The steam contains a combination of essential oils and water. The respective molecular structures of essential oils and water result in a separation in the chamber which renders the essential oil ready to use.
Cold pressing is primarily used to extract oil from the peels of citrus plants, such as oranges, limes, and lemons. This method was originally performed entirely by hand but is now managed by dedicated machinery.
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Cold pressing is required for citrus oils because they cannot handle the heat used for steam distillation. Instead, cold pressing relies on large amounts of pressure to force the oils from the plant. Modern machines are also designed to pierce and spin the peel of the citrus fruit while applying pressure.
Some plants are too delicate for either of the extraction methods mentioned above. In the past, they were handled with the use of solvents like petroleum or ethanol. This would produce something known as an absolute. Enfleurage is an example of using a solvent to produce an absolute. The difference between an absolute and essential oil is the manner in which it is derived. The two are very similar and are often used interchangeably.
In the past, some people were cautious about the use of absolutes because they may retain small amounts of the chemical solvent used to extract the oil. This is no longer a problem due to the development of CO2 extraction, which leaves behind no potentially harmful compounds.
The carbon dioxide extraction technique is superior to a petroleum or ethanol solvent method. It relies on increasing pressure to cause a phase shift in the carbon dioxide. During this shift, the carbon dioxide becomes part-gas and part-liquid. After extracting the essential oils, the pressure is decreased, and the carbon dioxide returns to a purely gaseous form with no residue left behind.
Tinctures, Isolates, and Infusions
A few additional terms you may encounter in the world of essential oil extraction techniques include tincture, isolate, and infusion.
An infusion involves combining a particular essential oil with a carrier oil. The carrier oil dilutes the essential oil and facilitates its absorption into the skin. This is particularly important for oils that are potent enough to cause skin discomfort or damage in their undiluted state.
A tincture involves soaking a plant or oil in alcohol instead of using a carrier oil. The resulting compound can then be ingested. This is not particularly common in aromatherapy.
Finally, an isolate refers to a particular compound from an essential oil that has been isolated and removed. Once an isolate has been produced, it can then be used in any number of applications or products.
Although the methods described above are unique, they all have the same primary purpose: extracting potent plant compounds in ways that maximally preserve the aromatic properties and health benefits of the given essential oils.
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