Lesson 2: Distillation


Required Reading

Foundational Aromatherapy 1st and 2nd edition pages 3-5

Where Do Essential Oils Come From?

Essential oils are derived from many different plants and many different parts of plants. Some plants carry their precious oils within their leaves or flowers, while others may carry the beneficial oils within their rinds, seeds, or other parts. Certain plants cannot produce enough essential oils to justify the commercial cost of oil extraction. Also, some plants may produce essential oils that have no known beneficial value or can even be harmful.
Lavender and chamomile come from a plant’s flowers, cedar wood comes from a wood, vetiver comes from tiny roots, orange and lime come from a tree fruit rind, and peppermint comes from plant leaves. Some essential oils can be extracted from multiple parts of a plant; for example, cinnamon can be derived from the bark or leaves of the cinnamon tree. There are many possibilities to all oils, and special care must be exerted to extract each essential oil appropriately.
Aromatic plants come from all around the world. Plants naturally grow in areas where the conditions are best for them. These conditions include climate, altitude, and soil conditions. Lavender is an oil that can be found on many continents and is used by many people. One fun thing I like to do is learn about the country where an essential oil originates. Then, each time I use that oil, it’s like taking a vacation to a faraway land.

Essential Oil Production and Quality

Knowing is appreciating. What do you appreciate most in your life?
Knowing about production and quality in the making of essential oils is important. It helps you to realize and appreciate the vast amount of work involved in order to obtain genuine, high-quality essential oils. Most of the work is still done by hand in small batches by families who have been doing it for generations, like the making of fine wine. Learning this brings deeper appreciation and higher value for our little bottles filled with precious essential oils.

Essential Oil Extraction

Essential oils are extracted by four basic methods, each of them very different, yet necessary, depending on the plants. Extraction means getting the oil out of the plant-from its flowers, roots, stems etc.—and into that little bottle for you to use and enjoy.

Steam Distillation

First, the most common extraction method is steam distillation. This method reminds me of bootleggers making moonshine during prohibition. A large metal container, made of either stainless steel or copper, is filled with a rather large amount of plant material. You can expect only a tiny amount of oil from such a quantity. For example, one drop chamomile is the equivalent of 30 tea bags of chamomile tea. After the plant material is put in the container, steam from boiling water is then funneled to flow through the plant material, causing the little oil-containing sacs on the plant to open or burst and release their tiny amounts of oil into the steam. Sometimes the water is directly under the plant material, like when you use a steamer basket to steam vegetables. In other cases, the material is covered completely in the water, like when you boil potatoes.

Currently, the most common steam distillation method is for the steam to be funneled through a tube into the plant material. Steam distillers can be taken right into the fields where the plants are harvested, and water heated using a wood fire. Alternately, plants can be processed in a high-tech facility where distillers operate using a heating element like a hot water heater. Next (this is where it reminds me of bootlegging), the steam then rises and winds its way through a coiled tube where it is cooled, usually in another container with cold water in it, and the steam turns back into a liquid. Oil and water naturally separate, so when the oil rises to the top of the water, it is removed. (Clove oil is the exception—it sinks.) Some distillers have two pipes—one for the water and one for the oil, making separation easier.

It is important to note here that essential oils are not really oils in the same way we think of traditional vegetable oils, like olive oil or grapeseed oil. But we call them oils because during the distilling process they rise to the top and float on the water like vegetable oils do. A better name for essential oils that is more descriptive and is now coming into use is plant essence. We may soon refer to essential oils as plant essences.

Cold-Press Extraction

The second most common extraction method is cold pressing. It is used to get oils from the rinds or peelings of citrus fruits, such as bergamot, lemon, orange, and grapefruit. It is not always desirable to distill fruit rinds because their chemical constituents are very delicate and the high temperatures used in steam distillation might damage or destroy them—with one exception—lime rind is better distilled.

To cold press, the peelings of the fruit are simply ground up and pressed at about 120° F, then the mass is filtered and spun in a centrifuge to remove the oil. The process sort of reminds me about being in elementary school, playing on the merry-go-round, spinning and spinning—if you did not hold on tight, you went flying off. The same thing happens in a centrifuge. The oil flies off into a container, nice and safe—safer than kids thrown off a merry-go-round who are left scraped up and bleeding, needing some oils!
The cold-press citrus oil that is spun out is the same as if you squirted yourself in the eye while peeling an orange for breakfast. The next time you have a citrus fruit in hand, smell it with the peeling uncut; then cut it and take a whiff of the peeling—pretty wonderful, yes! Citrus oils have a wonderfully light, fresh, and uplifting scent like that of the fresh ripe fruit. Citrus oils have a shorter shelf life than other oils. Citrus oils also are photo-toxic, which means when you put them on your skin and go out in the sun, they intensify the effect of the sun’s rays—which can cause a sunburn or even a permanent, weird, blotchy tan. Ask me how I know—well, let’s just say it’s not a good idea to use them on your neck as a perfume!

Solvent Extraction

The third method is solvent extraction. This is a very complicated process compared to the previous two. It is used for plants that are too delicate to steam distill, usually flowers such as jasmine. This process is very popular in the high-end perfume industry as it leaves an aroma very similar to that of the actual flower before extraction. It first requires a hydrocarbon extraction of the plant material that leaves a semi-solid blob of 50 percent wax and 50 percent essential oil. This blob is called a “concrete,” which is then mixed with ethyl alcohol—the same alcohol found in wines and beer. The alcohol causes the wax to separate from the oil, while the oil stays with the alcohol. The alcohol is then evaporated from the oil. The remaining oil is then called an absolute.

Neroli

Neroli

Rose

Rose

Rose and Neroli oils are unique because they can either be extracted as an absolute or can be distilled, a fact which is interesting to me. When they are distilled, it is done in boiling water, like potatoes, so the petals can float in the water and not clump up. This process leaves a very potent fragrance that can be overpowering. For this reason, these oils are usually combined with other oils in blends. There is some controversy in the aromatherapy world about whether solvent extracted oils are really true essential oils. Some hardcore Aromatherapists, especially medical ones, say no. In spite of all that, they do have a place in emotional based therapy and add a wonderfully complex aroma to essential oil blends.

CO2 Extraction

Fourth and last, there is a new method called CO2 extraction or super critical carbon dioxide extraction, to be more precise. For this method, the entire plant pretty much ends up in the final product. Carbon dioxide is put in a pressurized chamber with the plant matter at low temperatures around 35 degrees Fahrenheit. This low temperature and the fact that it is in a pressurized state turns it to liquid which “absorbs,” you might say, the aromatic qualities of the plant. The liquid is then pumped into another chamber where the carbon dioxide returns to a gas. What is left is a very pure extract of the plant. The resulting oil smells like the whole plant, and the flavors are excellent for cooking.
This last method is a very high-tech and expensive procedure. At present there are few facilities equipped for the process. Experts believe this method will become the wave of the future for aromatherapy because it’s low temperature which preserves many more constituents than traditional distillation, which uses steam and high heat. While the aromas of oils processed by this method are amazing, the process is expensive and still in its infancy. Time will tell.


Passport to Aromatherapy pages 16-17


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