by S. Pociecha
One of the questions people exploring aromatherapy unfortunately have to ask is:
"I understood that essential oils were the pure steam-distilled product of herbage. Now it seems there are lots of things sold as essential oils that are not pure at all. What's the story?"
I'd like to try to explain some of the terminology of the exciting field of eo adulteration - or eo engineering, as it's known among people who want it done. (Thank you Dr Robert Pappas of formerly of Applied Essential Oil Research, in 2013 of Essential Oil University for this useful term!)
I should clarify two things before we start:
1) In the US (at least), the term "pure" has no legal meaning and is often applied to just about anything;
2) None of the processes or products described below is inherently dishonest. There are whole industries that want engineered oils - that's why they exist. The ethical question - which is different from the legal question - is whether the oils are properly labelled so that end buyers know what they're getting.
"Extended oils" are eo's (or absolutes) diluted in carrier oil or a synthetic "filler". Some suppliers sell oils (especially the expensive ones) pre-diluted in a carrier like jojoba under the title "aromatherapy oils", so if you see that term on a label or in a catalog, be sure to ask what it means.
There are also some oils that are "normally" sold in a diluted form to make them pourable. Benzoin resinoid is the most common example of this: it isn't liquid in its pure form, so most suppliers dilute it so that you can get it out of the bottle. What it's diluted with, to what percentage, varies from supplier to supplier and you need to ask.
What is a co-distillation? I've found at least two processes called by this name:
1) Putting two different plants or plant parts in the still and steaming them together to produce one oil;
2) Adding an essential oil to plant material and distilling them together, again producing one oil.
Michel Vanhove adds:
"The main reason why codistillation is done is the fact that some plants, when steam distilled, contain only a very small amount of essential oil, for instance: Robinia pseudacacia (Acacia), Crataegus oxyacantha (Hawthorn), Tilia sylvestris (Linden or Lime tree), Melissa officinalis (Melissa). The price of these oils would be prohibitive to most consumers, so they're often extracted with solvents, to provide a higher yield - but this rules them out for medical use. So some distillers produce these oils by codistillation.
Two methods are possible: the distillation of two botanically different plants, or adding essential oils together with the plant during distillation. The product obtained will have similar medical actions to the pure essential oil. Here the experience and knowledge of the distiller is very important: the choice of synergy is not an easy one. It is normal that the essential oils obtained by this method should receive adequate labelling, indicating the production method."
What is bulking? This term refers to two different processes:
What is bulking? This term refers to two different processes:
1) The post-distillation combining of oils from one or more species. The most common reasons for this type of bulking (aka blending) are to make the product cheaper and/or to make it conform to some standard which may be desirable from the viewpoint of the fragrance or flavouring industries.
2) Piling plants from different harvests into the still together - one species, I mean, but grown in totally different parts of the globe under totally different conditions; sometimes dried plant material from different years may be bulked together this way. Again, the most frequent reasons for this are to make the product cheaper, or to make it conform to standards that some industry deems desirable.
This should not be mistaken for what is commonly known as "pre-distillation communelling", that is, the combining of several small harvests of the same species, from the same area, and during the same season, as a necessity that springs from the lifestyle of the wild plant. Butch Owen, an eo broker who works directly with distillers in Turkey, explains:
"In Turkey, it is the responsibility and privilege of certain families from certain villages to gather the local "wild grown" plants like rosemary, myrtle, bay and oregano from specified areas. This privilege of area exclusivity is unwritten, somewhat ancient and enforced in one way or another. One does not go into an area that has traditionally been harvested by another group.
Accordingly, when those peasants bring in the bags containing their harvest of wild plants (normally 60 kg bags) they are coming from many directions within an area perhaps 2 or 3 miles from their village. They are picking from the hills, the valleys, the edge of the forest and where ever they find the wild plant - as long as it is within their traditional area of harvest. All of this harvest is necessarily combined by the distiller and prepared during one distillation.
Keep in mind that some of these distillers are "cooking" upwards to 500 kg of raw material at a time - and even then, the amount of oil is not that great. Much of the oregano, for example, yields as little as 16 - 18 kg of oil per metric ton. Imagine the time that would be involved, and the resultant cost if the distiller were to cook the oils separately as the peasants brought in the materials - 60 or 100 kg at a time.
These materials are, of course, sorted according to species and as the sellers of the raw materials want to maintain goodwill with the buyers, there will be no case where a peasant would consider mixing Beyaz oregano with Sivre or Yayla or Isparta or Anamur oregano, etc.
The oils obtained from these "wild harvests" are pure, unadulterated and, I might add, quickly sold as they are in high demand. Accordingly, there is also no reason for the distiller to mix raw materials. It's not a matter of ethics - it's simply a matter of economics driven by supply and demand."
There are also rectified oils: oils that have had natural components removed from them: terpeneless oils, for example, and furocoumarin-free oils. Another term for rectification is redistillation.
Folded oils are oils (usually citrus) that have been redistilled a number of times to remove more of the (usually) monoterpenes to make the oil more desirable for the flavouring industry.
There are also oils that have had natural or synthetic chemical components added to them after distillation. These may be called reconstituted oils.
There are also blends (aka synergies), which I generally understand to mean something someone creates from various selected eo's and (if that someone is a vendor) sells with pride.
Again: All of the products described above can be sold with pride, as long as they're sold under their right names to people who have a use for them.
Which - if any - of them has any place in aromatherapy is another question, and it probably has as many answers as there are aromatherapists.
Copyright © 1997. S. Pociecha
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