The term essential oil dates back to the sixteenth century and derives from the drug ‘Quinta Essentia’, named by the Swiss physician, alchemist, lay theologian, and philosopher of the German Renaissance and pioneer in several aspects of the “medical revolution”, Paracelsus von Hoheheim of Switzerland (Brenner 1993). The first distillation process is dated back to the ninth century when the Arabs brought essential oils to Europe. In the sixteenth century, methods of extraction were more common and by the end of the nineteenth century, chemists have isolated, separated and reproduced the active molecules of essential oils in perfumery, therapy and other industries.
Essential oils are extracted in various ways and that has a dramatic effect on their chemistry and medicinal properties. Oils from second or third distillation are not as potent as oils extracted from a first distillation. Also some oils are exposed to high heat and pressure which deteriorates their chemical profile.
Essential oils are composed of hundreds and sometimes thousands of chemicals. An essential oil like lavender is very complex with many of its constituents occurring in minute quantities.
Heat breaks down many of these delicate compounds within essential oils. That is why it is a great concern to find out if the essential oil you purchase is adulterated, engineered or “extended” with synthetic chemicals.
It is very hard to tell even with gas chromatography how to identity poor quality oils.
