Getting the Highest Quality Essential Oils
Most essential oils worldwide are produced for the flavor, fragrance and toiletry industries. Because these industries have no need for a natural product, these oils are usually industrially processed. It is common for "nature-identical" synthetic substances or other compounds not originating from the plant to be added. We strongly recommend that you use essential oils that are produced for aromatherapy only.
Therapeutic Essential Oils
For an essential oil to be useful therapeutically, it must be very high quality. This depends upon the climate and geography where it is grown, what kind of farming methods the farmer uses, how the plant was harvested and how the oil was distilled.
Many flowers like violet, gardenia, freesia or lilac are not available as an essential oil because they are too delicate for distillation, too expensive or spoil too easily. Artificial oils may smell surprisingly real to an untrained nose, but they are not therapeutic. The best way to be sure of purchasing a true essential oil is to read the label, ask questions and find a company that is trustworthy.
Ask your retailer what he or she knows about the supplier:
Is the country of origin known?
Does he or she know the botanical species?
From which part of the plant was the oil distilled?
How was the oil produced?
Ask about the extraction method used to produce the essential oil:
a) Steam distillation
Most essential oils are steam distilled. During distillation, the fragrant plants are exposed to steam until the essence evaporates. The oil-laden steam then rises through tubing, where it is cooled. When the steam condenses, the oil is found floating on top of the water and can be easily separated out. Master distillers know the right pressure, temperature and duration for each kind of oil.
b) Cold pressed
Citrus oils are often cold-pressed to derive a better aroma. The peel is shredded and then mechanically pressed. The resulting liquid is filtered or passed through a centrifuge to skim the oil off the top of the liquid. Because many growers spray pesticides directly on the peel of citrus fruits, it is important to look for organic, cold-pressed citrus oils.
c) CO2 extracted
Oils like Coriander and Ginger, which are made from dried plant material, are sometimes extracted under pressure, using liquid CO2.
d) Absolutes
Blossoms that are too delicate to withstand high temperatures are sometimes extracted by solvents. Jasmine and Rose are sometimes solvent extracted. The plant material is put in a solvent like hexane. The solvent is then removed by evaporation; the product is mixed with alcohol to remove waxes and then distilled to remove the alcohol. Absolutes retain a miniscule trace of solvent.
Excerpt from "Aromatherapy for Every Day" by Christoph Streicher and Karla Christensen.