Aromatherapy: A New Journey
The Different Methods of Extraction
and their effects
by Hank Friedman
Since I started exploring and collecting aromatic oils, I've learned a lot.
There are several different methods of extracting the essences of plants, and each gives a very different product.
Steam distillation and hydro-distillation boil water (sometimes at reduced pressure in order to lower the boiling point), to distill off the volatile components of a plant. The hydro-distillation places the plant material in the water before heating it, and the steam distillation places the plant material in a flask above the boiling water, so only the steam touches the plant.
These are the main methods of extracting essential oils. They are a very effective methods of separating the volatile essential oil from the plant matter. (The heat -- in some uncommon cases as mentioned below -- can alter the constituents, and there are many large molecular weight substances that remain behind.)
Solvent Extraction. To make what are called Absolutes, plants are soaked in solvents (usually hexane) to extract their volatile components. Only the oil-soluble constituents dissolve in chemical solvents. When hexane is used, however, it is impossible to remove all of it from the end product, and hexane is toxic in parts-per-billion, and so absolutes can only be used in perfumery and for external applications.
Because no heat is involved, absolutes have more complex and rich scents than most steam-distilled oils, especially because the best components (which are the most volatile) are captured by the solvent, not lost as they usually are during steam distillation.
Only of few companies offer hexane-free absolutes, which can be used both externally and internally.
Enfleurage, on the other hand, is the gentlest of processes. Used only for extracting the fragrances from flowers, the procedure involves placing thousands of flowers into palm oil until they release their fragrance into the oil, removing the flowers, and repeating this process until the oil is saturated. Then the fragrance is extracted from the palm oil with alcohol.
The result is a very ethereal "top-note" oil that really smells like the fresh flowers. [However, the scents of enfleurage oils are less dimensional and less well-rounded than by other methods because middle notes and lower notes are not present.]
I got an exquisite Jasmine enfleurage here that is one of the most refined fragrances of jasmine I've ever smelled (and I have a whole collection of jasmine extracts). However, while the scent of enfleurages are exquisite and ethereal, they are too subtle to use in cooking, e.g. in my famous jasmine truffle recipe.
The Florasol/Phytol extraction method is little used currently, but produces a result remarkably similar to enfleurage. The method extracts the essences from plants at room temperature using an inert fluorocarbon under mild pressure, and then evaporates the fluorocarbon (and recycles it), leaving only the pure oil behind. It is a very cost-effective (low energy consumption) method and I purchased a jasmine florasol recently and it was quite lovely.
There are two different Carbon Dioxide extraction methods, called Select and Total. Both methods use much lower temperatures than steam distillation, and therefore capture the most precious (most volatile) fractions of the oils. Because CO2 is also able to extract both non-polar (oil soluble) and polar (water soluble) components, the extracts have more of the properties and the scent of the whole -- and fresh -- plant.
The select method, often abbreviated SE, produces oils much like those of steam distillation in consistency, by soaking the plant matter in CO2 that is minimally compressed into a liquid state, and then letting the CO2 evaporate. If you want a flowing liquid of great purity, that has all of the liquid constituents of the plant, this is an excellent choice.
The CO2 total method, which is more commonly used, uses much higher pressures, and results in a thicker, more waxy product that contains virtually all of the soluble material in the plant. Often CO2 total extracts are almost solid, and need to be diluted with a carrier oil (e.g. Jojoba or Fractionated Coconut Oil/MCT) in order to be usable. Nevertheless, total CO2 extracts represent the content of each plant more completely than any other method.
P.s. Since CO2 extraction methods pull most of the constituents out of the plant material, if they are to be used internally (with expert guidance) they need to be extracted from organic or wildcrafted plants because otherwise pesticides can be present in a concentrated form in the extract.
Molecular Distillation (aka Fractional Distillation) is a new method I've stumbled across. This method uses a high vacuum to distill oils at much lower temperatures, enabling the distiller to capture the most volatile (and best) fractions of the oil, remove impurities, and extract one component of the oil at a time, and reassemble it after distillation.
However, I've discovered that this method is often used to "shape" the scent by eliminating specific fractions/components, and as such does not always represent the fragrance of the actual natural oil.
White Lotus Aromatics -- see the next segment of this blog -- offers several oils distilled by this method, and they are exceptionally pure, well-rounded, and lovely.
As I mentioned in Part Three, Dr. Kurt Schnaubelt taught me that the aromatic oils in plants are their voices, and the other non-volatile substances in their tissues represent their bodily fluids.
The voices were meant to be heard, and to communicate with other organisms, while their bodily fluids, in many cases were not.
All of the methods besides the CO2 extractions only get the volatile "voices" of the plants, while the CO2 extractions get both.
In general, it is better to use oils obtained via CO2 extraction if the plant is one that is an herb or spice, i.e. meant to be eaten or infused as a tea. That's why ginger, turmeric, black pepper, chamomile, lavender and many other oils are best when created by CO2 extraction.
On the other hand, I've found that flower oils, like tuberose, jasmine, honeysuckle, and gardenia, are much better when they are not obtained by the CO2 method, because extracting the extra components (via CO2) makes the fragrance off, hampered, if you will, by the components never meant to be in an essence.
Even the exceptions prove the rule. I've purchased three lavender CO2 extracts. Their scents are clearly quite different from, and not as fine as, the best lavender oils I own. And yet, because they have significantly more and different components than all of my steam-distilled lavender oils, they smell more like fresh lavender, and their effects on consciousness are much more profound, and I would expect their effects for other purposes would also be superior to other lavender oils. [Note: remember that lavender is an herb that is ingested.]
In the case of Agarwood/Oud, the CO2 agarwood oils that I have are very thick, pungent, full of earth scents, and not perfumey or refined, but their potency is profound, they are less expensive than the fancier high-end Ouds, and they are quite transformative.
So I've come to have great respect for the CO2 extracts, especially for their effects and not necessarily for their fragrance. And I recently read that in a few cases, they are clearly the best for therapeutic purposes. E.g. German Chamomile has a constituent called Matricine that is converted by steam distillation into another substance, thereby losing 90% of its anti-inflammatory properties, so one should always use CO2 extracted German Chamomile if possible.
The journey of scents continues to be incredibly fascinating and educational to me, and I hope that my chronicle proves useful to you.
End of Part Four
(Note: Unlike many websites that "review" essential oils but are actually making a profit by selling oils via affiliations, I have no financial relationship with any aromatherapy company.)
Aromatherapy: A New Journey
Finding the best essential oils
The Essential Oil Company
I didn't want to love
How to evaluate essential oils
A Phenomenally Great Essential Oil Company
Essential Oil Shootouts
and also, my blog on:
The Magical oil called Oud
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