What are essential oils?
Let's first examine the two types, or families, of oils. There are “fixed oils”, which are non-volatile oils, and there are "volatile oils”. Essential oils belong to the family of volatile oils.
Non-volatile oils (i.e. olive oil, grapeseed oil, coconut oil, etc.) do not evaporate into the air, whereas volatile oils (essential oils) will quickly evaporate, and also pass more easily and more quickly through the skin barrier and into the body. If you rub olive oil onto your skin, there is a “greasy” or “oily” look and residue that will remain on the surface of your skin. When you rub essential oil onto your skin, you will notice after a few minutes it has evaporated–the oil moves into the cells, tissues, organs and bloodstream.
Where do we find essential oils?
Essential oils are obtained from plants. The oil is extracted from different plant parts, depending on the oil. It can be extracted from the leaves, flowers, roots, bark, peels, etc.
How do we obtain the essential oil from the plants?
There are different methods of extraction that are used, and the method used depends on the plant material or of course the equipment availability. There are three basic methods used: Steam distillation, expression (often referred to as “cold-pressed”), and carbon dioxide (CO²) extraction.
Steam distillation is the most common. In this process, the plant material is exposed to steam. The steam from the boiling water carries the vapors to a condenser to be cooled, and then it is returned back to liquid state. Oil and water do not mix, thus they go through a natural process of separation, and you are left with essential oil and hydrosol, or floral water.
The expression, or “cold-pressed” method, is used for obtaining oil from citrus fruits. This method is used because the heat used in the steam-distillation process damages the citrus oils. There is another, more modern, method of “expression” referred to as the écuelle à piquer process (direct translation = basin, to prick/stick/prod). In this method, the fruit is placed in a device and rotated with spikes on the side puncturing the oil cells in the skin of the fruit, and the essential oil collects below.
The carbon dioxide extraction, more commonly referred to as “CO² extraction”, uses CO² to carry the essential oil away from the raw plant material. The difference in using the CO² extraction method rather than steam distillation, is that instead of heated water or steam being used, CO² is used as a solvent, and none of the constituents of the oil are damaged by heat; thus, producing the most pure and unaltered essential oil.