Aromatherapy and the Essential Oils
Aromatherapy and the Essential Oils
The oils are volatile fractions, often of great molecular complexity, which are sourced from many families of the plant kingdom. The oils are produced as a part of the plants metabolism. There is as yet no scientific consensus as to their purpose within the plants economy.
The volatile oils are soluble in alcohol and sparingly so in water. In most cases the boiling point is in excess of 200 C. When distilling the oils, the rule of immiscible liquids will apply. Accordingly the oils will distill over, at the boiling point of water at normal atmospheric pressure. The finest oils are produced by distillation under reduced pressure.
As a general the rule the oils contain from 2 to 30 parts of hydrocarbons, e.g. Terpenes, Sesquiterpenes and Polyterpenes. When the oils are incorrectly stored, the terpenes are subject to oxidation and will produce objectionable odours. The terpeneless or concentrated oils are produced by fractional distillation. However for therapeutic purposes the terpeneless oils are to be eschewed.
The oils represent only a small part of the plants total extractive, often less than one half of 1%. In odd cases, for example, oil of clove and nutmeg, the average yield is around 12%. As a general rule the greater the yield the lower the price whilst in the case of violet or rose the price is astronomical, which reflects the meagre yield. Unlike the fixed oils they do not leave a greasy stain and will evaporate rapidly when exposed to air .Decomposition occurs when exposed to oxygen or sunlight. They should be stored in tinted, tightly stoppered glass bottles in a cool dark place. Adulteration is common place due to the high price that they command.
How are the Oils Obtained ?
The method used to procure the oils will depend upon the end use requirements and in a few cases upon the average yield of the plant part being operated on, e.g.
[A] Steam or water distillation. Water distillation is used for many types of petals such as rose which if steam distilled tend to produce a soggy mass, through which the steam cannot penetrate. Barks and wood are also water distilled. Otherwise as a general rule leaf stem and flowers are steam distilled.
[B] Expression or pressure. This method is only suitable for fresh citrus peels.
[C] Sublimation or destructive distillation e.g. Oil of Cade [Juniper Wood] or Stockholm Tar obtained from pine wood.
[D] Solvent extraction. This method is not suitable for the medicinal oils although it is widely employed for fragrance purposes. The problem is 2 fold, firstly the solvents are not too selective so that after solvent evaporation a semi soft mass is left which are known as Concretes which must then be further processed to produce the Absolutes. As a general rule the solvents employed are highly toxic and total removal of their traces is not feasible.
[E] Maceration which is carried out in a fixed oil. When ready they are known as perfumed oils or 'Huiles Antiques'. When infused for medicinal purposes they are called 'Infused Oils'.
[F] Enfleurage is a semi maceration technique in which flower petals are spread on a Fat which was usually purified lard. The petals were exchanged for fresh at regular intervals until the fat was saturated. Obviously the method is cumbersome and very labour intensive.
As a technique it is now rarely used and is reserved for a special class of flowers where the yield is low and where the flowers continue to manufacture oil even after being picked a good example being Jasmine.
How do the Oils Work ?
The oils act in tandem on two levels, the mental and the physical. Remember that your mental state reflects your chemical composition and vice-versa. Our sense of smell is the most powerful, evocative and primitive of all of our senses. The filaments of the olfactory nerves are distributed in the upper nasal mucosa which transmits chemical messages to the brain on a deep level. These volatile chemical messengers invoke the whole range of emotional responses, and produce vivid mental images of long buried memories. The physical response is characterised by the usual pharmacologic response to plant substances e.g. Diaphoretic, Diuretic, etc. The oils being an isolated constituent of the plant do not represent the full therapeutic spectrum of a whole plant extract, and the physiologic response of the organism is greatly modified. In the hands of a skilled and sensitive Aromatherapist the essential oils are a powerful healing medium and should be a part of any holistic practice.
The Oils in Commerce.
It is a valid observation that when any society has resolved the basic problems of food, warmth, shelter and medical care, then the beautiful art will arise, the core of which is fragrance. The commercial possibilities of the new 'volatile oils' would have been seized upon eagerly by the medieval apothecaries both secular and monastic. Today we still have many fine remnants that testify to the skill of those proto-perfumers many of which bear the name of the patron that commissioned them e.g. Queen of Hungary Water. Aromatic waters still maintain a place in many modem Pharmacopoeias.
By the mid 19th century the world trade in aromatics was astronomical, and all roads crossed in Europe. For it was there that the foundations of the technological advances of the 20th century were being laid. When the Great International Trade Exhibition was held in Paris in 1876 well over 100 essential oils were general items of commerce. Demand was outstripping supply, so the chase was up. Large commercial plantations of aromatics were established. Vast strides in chemistry were being taken, and the first synthetic aromatics became items of commerce, just as they are today. Although let it be said, that the chemists mirror image molecules lack the ethereal and evocative subtleties of nature. The natural oils are optically active, the synthetics are not. Today the fragrance and flavour industry is an international undertaking. The industry spends millions of dollars each year on research, but the finest of their offerings are still sourced from Nature. And it still takes the human nose, to detect that, which the chemist cannot.
It is given that the term 'Aromatherapy' was first used by a French Chemist and Perfumer, Rene Maurice Gattefoss circa 1928, who was led to scientifically examine the effect, of essential oils when used topically. Gattefoss was not the first. Many scientific studies had already been conducted on the therapeutic effects. For example, at a time when tuberculosis was still a scourge, it had been noted, that the incidence of the disease was remarkably low amongst those workers employed in the essential oil industry. They were exposed on a regular basis to the volatile vapour, of the oils, and to oil of lavender in particular. Unfortunately, the downside was, that although the oils, displayed excellent anti-microbial activity, it was also found that many of the long term employees, also suffered a variety of distressing symptoms that were unrelated to anti bacterial effect. That fact caused the medical community to lose interest and move into more promising areas. Quite clearly the workers, were suffering the effects of an overdose.
A major figure in the early days of Aromatherapy, was the French Physician, Dr Jean Valnet, whose clinical experience with the oils was gained as an army Surgeon during World War 2, and who's book 'The Practice of Aromatherapy , was a major landmark in the growth of the therapy. Also influential was the Bio-Chemist Marguerite Maury who lectured and taught unceasingly and still found time to establish 3 international clinics, to cater for the increasing demand. However it was not until 1977 that the attention of the English speaking world was captured by the publication of. book called 'The Art of Aromatherapy' which was written by a masseur called Robert Tisserand Today Aromatherapy is a fully fledged therapy in its own right. It is both an art and a science, but remember it is not all embracing, it is complementary.
Small scale domestic production may be satisfactorily undertaken by modifying a stainless steel pressure cooker or boiling pan, of suitable size, i.e., the capacity should exceed 5 litres to be economic in operation. The herb is then suspended above the boiling water in a basket. The need for a separate steam generator is eliminated and the risk of charring removed. The herbal material may be in the fresh or dried form. If dried, then the material must first be macerated before the distillation process is commenced.
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