I am not saying here that all plants are without risk, simply that the clean record of traditional use together with up-to-date hospital research projects, trials and general case studies should be sufficient. Misuse is a different matter and is covered in chapter 6, as are the differences between herbal medicine (in which many very toxic plants are used, e.g. boldo, tansy, etc.) and aromatherapy (which does not use the oils from any of these potentially dangerous plants).
Good, wholesome food is of itself a medicine, and it is a well-known fact that the development of many diseases is in direct proportion to the development of additives and synthetics together with the use of growth hormones and fat inhibitors to produce bigger and better plant and animal foods.
When looking back in history for the origins of aromatherapy, it is as well to remember that aromatherapy has but a short history, the word being coined only relatively recently. The history we have been looking at has been that of plants, their extracts, compounds and essential oils. Although the latter are the essentials of aromatherapy (in the therapeutic sense), they are not limited to this particular aspect in their use, being extensively used in the perfume, cosmetic, household and food industries.
‘The Lord hath created medicines out of the earth and he that is wise will not abhor them.’
FIGURE 1.1: A 19th-century French lavender still (by courtesy of Raspail of Saillans)
Although the basic principles for extracting essential oils from plants remain the same as hundreds of years ago, tremendous advances have been made in the techniques used and the methods employed. Distillation is, and no doubt will continue to be, the most important of these.
Steam Distillation
Essential oils are contained in the glands, veins, sacs and glandular hairs of aromatic plants. Flowers, leaves and non-fibrous parts need little, if any, preparation prior to distillation. Tough stalks, woody parts, roots, seeds and fruits, however, need to be ‘comminuted’ (cut up, disintegrated or crushed – wood is grated) in order to rupture the cell walls, allowing the easy escape of the volatile oil. (Volatile is derived from the Latin volare – to fly.)
Distillation is still considered to be the most economical method of extracting essential oils from plant materials.4 Some plants have to be distilled immediately they are harvested, for example melissa; if left even a few hours, the essential oil is lost – the yield from melissa is, in any case, very low. Some plants are left a few days, e.g. lavender, so that surplus water in the plant can dry out – this, by the way, slightly affects the yield. Some, like black pepper seeds, clary (clary sage) and peppermint, can be totally dried before distilling without losing any essential oil. It can be seen from these few examples that there is an art to distillation and that, especially for low-yield plants, much skill is needed. The role of the distiller is to achieve an oil as close as possible to the oil as it exists in the plant.
We distil water every day each time we boil a pan or kettle – the heat lifts molecules of water from the surface and they evaporate into the air, or condense as distilled water on the pan lid.
During distillation, only very tiny molecules can evaporate, so they are the only ones which leave the plant. These extremely small molecules make up an essential oil. Oils containing more of the smallest and therefore most volatile of these tiny molecules are termed ‘top notes’ in the perfumery world; those containing more of the heaviest and least volatile of the tiny molecules are called ‘base notes’. Those in between are known as middle or sometimes ‘heart’ notes.
FIGURE 2.1: Steam distillation
When plants are heated by steam in a still (alambic in France), the essential oils present in the plant material are freed, evaporating into the steam. These tiny molecules are carried along a pipe together with the steam and as they get further away from the heat source they begin to cool. To hasten this process, the pipe passes through a large vat of cold water (the important addition to distillation contributed by Avicenna around AD 1000) and condenses back into liquid form. As the density of essential oil differs from that of water, it either floats on the top or sinks to the bottom (mostly the former), where it can be drawn off. The result is a pure, genuine, whole and natural essential oil – an aromatherapist’s dream! This is the oil used in any reference or research carried out before the 19th century, when there were no synthetics to adulterate or ‘ennoble’ nature’s gifts.
Distillation is more complex than I have made it sound (books have been written on this subject alone) but the underlying principle is simple to understand and remains unchanged.
Aromatic Waters
These are a by-product of distillation and contain some of the properties of the essential oil, even though it may be thought that because essential oils float on water they are not water-soluble. Some essential oil components do dissolve in water, and these, together with larger molecules from the plant (too large to vaporize, but soluble in water), form the aromatic water. Because of the presence of these other molecules, genuine waters have a different aroma from the essential oil of the same name.
The water from plants with a high yield of essential oil is normally discarded – directed into the nearby stream (large stills are always located beside a stream or river). However, with low-yield oils like melissa, rose and neroli, producers cannot afford to lose a single drop of the precious essential oil, so a special method called ‘cohobation’ is used, requiring a highly technical still and an experienced distiller. The basic process is as described above, except that, instead of using fresh water for each new plant load, the same water is piped back into the system, and used over and over again. Eventually, this water becomes saturated with the water-soluble elements from the plant (and water-soluble essential oil components). At this stage, every particle of volatile oil condenses and is collected at the end of the process to make a complete oil.
This saturated water is very concentrated and this strength is good for transport, as it saves on freight costs: it needs to be diluted with pure water to be comparable in strength with other plant waters. Lavender, clary and other waters from normal distillation are not as cheap as one would think (considering they are thrown away unless specifically ordered in advance), because of the cost of packaging and transport.
Before Avicenna’s improvement to distillation and before cohobation was thought of, rose and neroli flowers were distilled simply for the water – the amount of essential oil obtained was negligible. In Tunisia, our friend Manoubi’s mother, like many Arab women today, has her own tiny still, in which she makes orange flower water for her own medicinal and culinary use.
Unfortunately, unless one has a good connection in the country of origin (which, fortunately, we do), it is as difficult to buy untampered-with aromatic waters as it is to buy untampered-with essential oils (almost all rose water available in pharmacies is made with synthetic substitutes).
Aromatic waters can be made from plants which have no essential oil, by using diffusion.
Carbon Dioxide Extraction
This is a fairly new method of extracting essential oils, introduced at the beginning of the 1980s, utilizing compressed carbon dioxide. The technology calls for very expensive, complicated equipment (initially three or four