Essential oils are pure, natural, volatile, aromatic substances created by specialized secretory cells in plants and extracted by distillation with water or steam, cold expression, or dry distillation. While still in the plant these substances are known as essences.
Once they are distilled they are called essential oils. These highly concentrated substances may be extracted from flowers, grasses, leaves, bark, fruit, wood, resin, roots, rind and/or seeds. These plant juices make up the intrinsic, fundamental nature of the plant itself.
Plant essences (the substance within the plant) are chemically complex structures created by energy obtained from sunlight combined with the chemical elements found in the air, soil and water surrounding the growing area. When these essences are extracted from the plant, it is this complexity that allows the oils to be effective, generally safe, and extremely versatile.
Chemistry is the foundation of aromatherapy. Each essential oil is made up of a wide array of chemical constituents that affect the physical, mental, emotional and spiritual states of a being. Each inhalation of an essential oil creates an electro-chemical response impacting the brain and other portions of the nervous system, simultaneously small components of the essential oil enter your lungs. From there these constituents are delivered throughout the body via the bloodstream. When essential oils are applied to the skin, the minute molecules enter the circulatory systems and are distributed throughout the body. A bath with essential oils can be quite an effective delivery method – studies have shown that penetration of the dermis (skin) is increased 100-fold if essential oils are added to a bath – plus there is the added benefit of the relaxation of the bath itself.
METHODS OF EXTRACTION
In the true sense, essential oils are either distilled or expressed (Arctander 1960).
The most common ways of distillation can be completed via water, water and steam or steam alone. Distillation involves using a still to heat the plant material to a temperature high enough to produce a vapor then cooling that vapor to cause condensation into a liquid form.
Water distillation – plant material is covered by water and slowly brought to a boil
Water-Steam distillation – plant material is mixed with water and subjected to steam
Steam distillation – plant material placed on grid and pressurized steam blown through it
Cohobation – the water used in an initial distillation is added back to the still with the plant matter for re-distillation, used to recover water soluble components lost in the first run – used to make Rose otto
Fractional distillation – usual distillation with interruptions at various stages to collect only the portion that has been produced to that point in the process – Ylang ylang essential oil is produced by this process – can be stopped and restarted up to 4 times with the first fraction being Ylang ylang Extra, and the following fractions referred to as Ylang 1, 2 and 3
Dry Distillation – plant material distilled, without water or steam, in a vacuum
Expression – citrus peels are scraped then the essence is collected by centrifugal separation
There are other methods of extraction that produce products often incorrectly referred to as essential oils. These are created by the use of solvents and applied to plants whose aromatic substance would be degraded by usual distillation.
Absolutes – this involves a three step process: 1) solvents are used to extract the essential oil of delicate flower petals, thus creating a concrete (a mixture of about 50% essential oil and 50% plant wax); 2) ethanol is then used to dissolve the wax; 3) the resulting mixture is filtered and the alcohol removed by distillation in a vacuum.
CO2, Hypercritical Carbon Dioxide – an excellent solvent that can extract essential oils quickly at a low temperature without any chemical reaction creating a pure plant extract. The disadvantage of this is some of the chemical changes created by steam extraction do not occur and the end product is not the same as the ones that have been researched and used in aromatherapy. As more research and trials are conducted, this may become an accepted part of aromatherapy.
ESSENTIAL OIL CONCENTRATION
Essential oils are highly concentrated. The amount of essential oil extracted from an aromatic plant can range dramatically depending on variables such as: weather conditions, soil, altitude, time of harvest, temperature, pressure and length of distillation. The percentage of yield from various plants range from 2% for Rosemary to .05% Lavender to .006% of Rose. That translates to approximately:
Eucalyptus – 25 lbs plant matter to make 1 lb essential oil
Rosemary – 50 lbs plant matter to make 1 lb oil
Lavender -200 lbs. plant matter to make 1 lb oil
Rose – over 16,000 lbs of petals to make 1 lb oil
PURCHASING ESSENTIAL OILS – What to Look For
~Every bottle of essential oil should have the common name such as Lavender; the botanical name, Lavandula angustifolia; and the country of origin, France. There are numerous varieties of Lavender, so it is important to know which one you want and what you are getting-the botanical name will tell you that. The country of origin is there because the location where a plant grows can alter the chemical make-up and the odor quality.
~Essential oils are sensitive to light and should be bottled in amber (brown), cobalt blue, violet (almost black) or green bottles to protect them. Never buy oils sold in clear bottles.
~Each bottle (from 2ml through 30ml) of essential oil should have an orifice reducer, a small plastic disk that limits the amount of oil dripped out of the bottle. This has a two fold purpose: in case of an accident it limits the amount of oils emitted and it also allows you to count the number of drops when creating a formula. Never buy essential oils in bottles with a rubber squeeze top (like an eye dropper). Many essential oils cause this rubbery top to disintegrate and contaminate the essential oil.
~Buy your oils from a reputable dealer with whom you can build a relationship. Whether using essential oils for the scent alone or for their healing potential, it is important to employ the highest therapeutic quality oils. Therapeutic quality means the essential oil’s chemical constituents fall within certain percentages and will therefore be effective in addressing specific needs. It is also indicates there are no artificial substances or additives in the product. Since there is no formal regulation (in the US), anyone can make these claims, so what is a person to do? I encourage you to communicate with the provider, ask questions and get a feel for their knowledge. You have a right to get what you are seeking.
STORING ESSENTIAL OILS
~Keep your essential oils in a cool, dry, dark place away from light and heat – closets or drawers are great. Do not store them in the bathroom or near a heat source.
~Keep the lid tight. Essential oils will evaporate and/or oxidize when exposed to air.
~Essential oils are flammable. Do not use them near an open flame.
COST OF ESSENTIAL OILS
The cost of essential oils can vary greatly depending upon:
*how much essence a particular plant produces
*how easily the essence is to extract
*how plentiful the plant is