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The |Home Herbal Preparations: Essential Oil Extraction Episode
Listen Essential Oils are the volatile chemical compounds contained within plants. Volatile because they are contained within sometimes delicate structure and oils which have very low boiling points. If not sealed either within the plant or in a bottle volatile the oils will escape into the environment. Essential oils are generally used externally for a multitude of therapeutic treatments. Although in strictly speaking, the term essential oil is in reference to the aromatic value of the oils alone. But given that the oil is a product of often the whole plant and even if just a single part, it would still contain many more chemical compounds besides just the aromatic ones. Second only to Tinctures for me is the wonderfully alchemical processes required to make your own essential oils at home. Though I must admit for the most part it really is easier to just buy them from your local pharmacy etc. to be assured of the quality of the essential oil. Large scale modern industrial methods of essential oil extraction are far more efficient and generally result in a superior product to anything that one can make at home in quantity and quality. Not that this deterred me nor should it you, to at least try out a couple of methods and see what you can achieve if you need or want to. There are four main preparations used to extract essential oils, they are generally used only by commercial industry due to their complexity, equipment and amount of raw material needed. The first is Steam Distillation and perhaps is the most used preparation of essential oils today in commercial industry. The raw plant is placed into a sealed alembic and sits above water. The water is boiled and the steam passes through the raw plant above and takes the essential oils with it. The steam is then directed through a condenser which is cooled to a specific temperature. The steam condenses on the cooler surface forms a liquid herbal distillate or hydrasol and runs out of the condenser to be collected in a sealed container. The essentials oils naturally rise to the surface of the hydrasol in the container and are removed. Given the right equipment steam distillation can be performed at home, but I would recommend a good amount of research etc before embarking on this venture. The second Solvent Extraction is far more complex but can result in very pure essential oils or Absolute Essential Oil and is really good for the large scale extraction of the more delicate chemical compounds because of its non-destructive (cold) preparation qualities. The initial preparation uses a chemical solvent such as hexane, a by product of crude oil distillation, or super critical carbon dioxide (SCCD). The latter is interesting because as we know when you drop carbon dioxide below its freezing point it becomes Dry Ice, raise the temp and it becomes a gas with no discernible liquid. But if you can pressurise carbon dioxide and raise the temperature to its critical temperature 31,1 °C it expands to fill its container like a gas but, and this is where it gets strange, as it will now have the density and properties of a liquid. Carbon dioxide in this state acts as a powerful solvent equal if not better to that of hexane, but as it is just good old CO2, it has no petrochemical residues and is far more gentle. The addition of SCCD or hexane results in the extraction of essential oils along with waxes, and resins and other compounds to form a Concrete or sold mass of all of them combined. The essential oils in the concrete are then extracted either using an alcohol solvent such as ethyl alcohol. Which would then undergoes a second distillation to separate the pure essential oils from the resulting solution. Or undergo further SCCD extraction lowering to specific temperatures which will separate the waxes etc from the essential oil. It is this second SCCD process which allows the extraction of very delicate chemical compounds that would otherwise be destroyed by other preparation processes. Also when the pressure and ambient temperature is restored the carbon dioxide returns to a gas leaving no residue. So by in large the SCCD process is the best process for essential oil extraction known today. Paradoxically considering its complexity within solvent extraction preparation is perhaps the most and easiest used home method to make your own essential oils. Home solvent extraction is similar to making tinctures but with a few differences and added processes. Using a glass or at least non-metal tightly sealable container place as much of the raw plant part used inside as you can, and fill with at the least 80 Proof or 40% ABV undenatured ethyl alcohol. Tightly seal and let sit for around 3 weeks, give it the occasional shake to mix things around and ensure exposure to the alcohol solvent. After the three weeks pour out the alcohol, remove the old raw plant and replace with new fresh raw plant, pour the alcohol back inside and top it up to the brim if necessary with more clean alcohol. Repeat this whole process 4-8 times. On the last time take the now fairly potent alcohol mix and place it into the freezer. The essential oils will solidify on the top, whilst the alcohol will remain a liquid. This solid mass should be quickly placed into appropriate tightly sealing contain, and as soon as it warms up again it will return to liquid oil. Though it does work and work well the end result is quite variable and not a guaranteed quality pure essential oil, but very useful nonetheless and considering what could be a large price difference between buying it straight of the shelf or growing it yourself or buying the fresh plant. The third essential oil extraction is Expression, which is the plant part is simply cold squeezed or pressed until the oils drip out. This is still a common method especially when the oil content is very high such as in Olives, Jatropha or Citrus. In the case of citrus the peel is simply gathered and then pressed. Though this method is aimed at wholesale large scale oil extraction and is unsuitable for plants which have comparatively tiny amounts of oil such as Rose. The last is an ancient perhaps oldest preparation still in use today called Enfleurage, which is strictly speaking a solvent extraction preparation. Enfleurage was until recently the only way to extract delicate chemical compounds such as those found in flowers favoured by the long standing perfume industry like Jasmine. Try reading Patrick Suskind’s Perfume for an in-depth look at enfleurage, perfume and one man’s obsession with the world of smell. Enfleurage can be divided into hot and cold preparations the latter being as non-destructive as possible until the advent of the SCCD preparation. In cold enfleurage large horizontal plates of thick framed glass are smothered with purified animal fat to the thickness of the frame and allowed to settle. The whole flowers, petals or leaves are placed onto the fat surface and sealed into the fat with a light smear. They are left to infuse the surrounding fat for 2-4 days after which they are removed and new plant material takes their place. This process is then repeated until the fat has the required essential oil concentration, in some cases that would be many months. The plates are then scraped clean into a container and mixed with very pure undenatured ethyl alcohol. This causes the essential oils to be removed from the fat and into the alcohol. The mix is then settled and separated into the solid fat and liquid alcohol, which is then allowed to evaporate leaving behind only the essential oil. With hot enfleurage only the first part of the preparation is different. Instead of using cold fat and glass plates, the purified animal fat is heated in a container and the raw plant is stirred into the hot liquid fat. This is done with measured amounts of the raw plant being stirred in, allowed time to render their compounds to the fat and then lifted out with a strainer and new raw plant added. This is repeated until the fat is at the required concentration and then cooled to room temperature and moved forward to the ethyl alcohol process. Though from the heat of the process much is lost of the essential oils and generally only the tougher more copious chemical compounds survive the process. Both cold and hot enfleurage preparations can be performed at home and with diligence and easy access to the required raw plant yield good results. Though as with all of these essential oil preparations that you may embark on, as I said in the beginning it is certainly easier to just buy them in their final bottled form. But if you’re like me then you will try them out anyway just to experience it and be able to do it again if necessary to. Plus it is really a whole lot of alchemical fun and I highly recommend to anyone willing to do the research and experimentation, you will be rewarded by the experience.This article was written By Ivor W. Hartmann at The IWH Inquirer.In this Series . Infusions . Decoctions . Tinctures . Essential Oil Extractions . Macerations .
[ Wed, 29 Oct 2008 07:44:58 PDT ]
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