Methods of Extracting Essential Oils

Application

While the practice of aromatherapy is sometimes thought to be confined to inhalation, it may include various methods, including:

* Inhalation (directly or diffused into the air)
* Absorption through the skin (baths, massages, compresses)
* Absorption through the mucous membranes (oral rinses and gargles)
* Ingestion (occasionally prescribed, with caveats)

Therapeutic Effects

Aromatherapy is based mainly on the following therapeutic effects:

* Antiseptic effects: viricidial, bactericidal, fungicidal
* Anesthetic action (menthol, camphor)
* Central nervous system effects
* Metabolic / Endocrine effects
* Psychological effectsImmunostimulator

Distillation:
The vast majority of true essential oils are produced by distillation. There are different processes used, however. In all of them, water is heated to produce steam, which carries the most volatile chemical of the aromatic material with it. The steam is then chilled (in a condenser) and the resulting distillate is collected. The Essential Oil will normally float on top of the Hydrosol (the distilled water component) and may be separated off.

Steam Distillation
True Steam distillation uses an outside source of steam which pipes the steam into the distillation unit, sometimes at high pressure. The steam passes through the aromatic material, and exits into the condenser.

Hydrodistillation
The botanicals are fully submerged in water, producing a "soup", the steam of which contains the aromatic plant molecules. This is the most ancient method of distillation and the most versatile. It's the method most often used in primitive countries. The risk, of course, is that the still can run dry, or be overheated, burning the aromatics and resulting in an EO with a burnt smell. Hydrodistillation seems to work best for powders (ie, spice powders, ground wood, etc.) and very tough materials like roots, wood, or nuts.

Cold Pressing
We are all familiar with the spray of orange essential oil that can be released by scoring or zesting the skin of the fruit. The cold pressed citrus oils are commercial produced just this way, by machines which score the rind and capture the resulting oil. Although many citrus oils are also produced by steam distillation, they seem to lack the vibrancy of the cold pressed oils.


Carbon Dioxide Extraction
When CO2 (carbon dioxide) is subjected to high pressure, the gas turns into liquid. This liquid CO2 can be used as a very inert, safe, "liquid solvent." which will extract the aromatic molecules in a process similar to that used to extract absolutes (above.) The advantage, of course, is that no solvent residue remains, since at normal pressure and temperature, the CO2 simply reverts to a gas and evaporates. CO2 extraction has given us essences of some aromatics that don't yield essential oils, Rose Hip Seed, and Calendula, for examples. If the same essential oil is available both as a steam distilled EO and a CO2 extracted essence, the CO2 seems to have a richer, more intense scent, since more of the aromatic chemicals are released through this process.

Water & steam distillation
A water and steam distillation arrangement can be compared to a kitchen steamer basket, with the botanicals supported in a "basket" over boiling water, thus exposing the plant material only to the rising steam vapors. This is the best method for distilling leafy materials, but doesn't work well for woods, roots, seeds, etc.

Florasols/Phytols
This extraction method uses a new type of benign gaseous solvents. In the late 1980s Dr. Peter Wilde first recognized the unique properties of these solvents for the extraction of aromatic oils and biologically active components from plant materials, for use in the food, pharmaceutical, aromatherapy and perfume industries. "Florasol" (R134a), is the solvent upon which the process is based Extraction occurs at or below ambient temperatures, hence there is no thermal degradation of the products. The extraction process utilizes the selectivity of the solvent and produces a free flowing clear oil free of waxes.

Thank You to Christopher McMahon of White Lotus Aromatics for providing much of the information below.