Producing essential oils involves
complex and elaborate equipment, and
is beyond the scope of anything
you can do in the home.
Most pure essential oils are extracted from plants through steam distillation. Freshly picked plants are suspended over boiling water, and the steam pulls the oils out of the plant. The steam rises, is captured in a vessel, and is pushed along tubing. Then the steam is rapidly cooled, causing it to condense back into water. Since water and essential oils do not mix, the two separate, and the essential oil is collected.
A byproduct of this distillation is the remaining water. Some plants contain aromatic compounds that are so water soluble, they remain in the water that is left over after distillation. Such waters are very fragrant and are prized by aromatherapists, who refer to them as hydrosols. In aromatherapy, hydrosols are used mostly in cosmetics to moisturize skin.
The most direct method of producing essential oils is pressing them from the plant's flesh, seeds, and skins -- a process similar to that used to obtain olive oil. This technique is used mostly with citrus peels, such as orange, lemon, lime, or grapefruit, because the oil in their peels is easily pressed out.
This very old method is rarely used today except in France. It is a long and complicated process that has become very expensive. Blossoms are set on sheets of warm fat that absorb the oil from the flowers. Originally animal fat or lard was used, but now vegetable fats are more common. Once the essential oil has been incorporated into the fat, the "exhausted" flowers are removed and replaced with fresh ones. The process is repeated several times until the fat is infused with fragrance. Then the fat is separated out with solvents, leaving just the essential oil.
Aromatherapists tend to shy away from oils obtained through chemical solvents, worrying that slight traces of the solvent may remain even though they are supposed to be completely removed. First, the plant is dissolved in a solvent such as benzene, hexane, or chlorure of methylene. The solvent, which has a low boiling point, is then evaporated off, sometimes with the help of a machine that uses vacuum or centrifugal force to help pull it away from the essential oil.
The resulting oils are called "absolutes." A similar method uses paraffin waxes as the solvent, but does not evaporate them off. Instead, the remaining paraffins cause the final product to be solid, and thus it is called "concrete."
Even though the evaporated solvent is recaptured and cooled back into liquid so that it can be reused, this process is still expensive. As a result, it is reserved for costly oils that cannot be distilled, such as jasmine and vanilla, or for rose essential oil, which is slightly less expensive when obtained through this process rather than through distillation.
New methods of obtaining essential oils are currently being introduced. One of the most interesting processes, although extremely expensive, extracts the oil with carbon dioxide. The delightful result is an essential oil scent that is very close to that of the plant itself.
Depending on the way the essential oil is produced the quality and concentration can be greatly affected.
Essential Oil QualitySince they are products of nature, the quality of essential oils is affected by growing conditions, the particular species of plant, extraction techniques, and storage, among other factors. Even the type of soil, temperature, and cloud cover affect some oils.
To determine the quality of an essential oil, you'll need to be concerned with three crucial characteristics -- purity, grade, and integrity. The information below and lots of experience will guide you.
Purity is an important concern to anyone purchasing essential oils. They can be adulterated, cut, or entirely replaced with a cheaper substitute or extended or diluted with vegetable oils, alcohol, or solvents. These substitutes and extenders might not be derived from a plant at all. But even if they are, the oil will not be as potent as it should be, nor will it function as expected. Unfortunately, a label claiming a product is a pure essential oil is no guarantee that it is the real thing. An oil labelled rose or vanilla may have been produced in a laboratory out of synthetic chemicals, but it can still be labeled an essential oil.
Inexpensive oils such as orange, cedar, or peppermint are seldom altered. However, alteration is common with expensive oils that are in great demand, such as rose, melissa, and jasmine.
Dilution with vegetable oil is usually easy to detect. Dilution with alcohol may be a bit more difficult to determine, but these oils do have a slight alcohol odor. Oils adulterated with a clear, non-oily solvent are the most difficult to recognize. This is a potential health hazard as well, since such solvents are readily absorbed into the body when rubbed on the skin or inhaled through the lungs.
Many essential oils are sold to distributors in different grades. Their prices often reflect this: The better grades command up to double the cost of the lesser grades. For example, lavender is commonly available in at least a dozen different grades and lemon in four. The lesser grades are often still pure essential oil, but they contain less of the most important aromatic principles.
Different processing methods can produce different grades. For example, redistillation produces oil that is stronger in some compounds than others. This is typically done with peppermint oil so the chewing gum and candy it flavors has a lighter, fresher taste and smell.
Once your nose has had a little experience with essential oils, you'll find that higher grades generally are more intense and carry a richer bouquet of fragrance. Lower quality oils usually smell less complicated or weak because they do not contain a full range of aromatic compounds.
When two bottles of the same kind of oil smell differently, it does not necessarily mean that one is better than the other. The best quality oils are similar to fine wine in that even experts don't agree on their favorites. For example, one geranium essential oil might carry a distinctly stronger hint of citrus while another smells more like rose. Which is better? Most people will prefer the rose, but that doesn't make it better.
By integrity we mean that the oil is pure and natural and comes from a single species of plant (and probably even from the same region and harvest). An oil with integrity is not whipped up in a laboratory or composed of cheaper essential oils. But inexpensive lemongrass or citronella essential oils sometimes masquerade as the very expensive melissa (lemon balm) oil. To make an artificial rose oil in the laboratory, rose geranium may be used as a starting point, then chemically altered to mimic, although never completely accurately, a rose scent.
The problem here is that although the end product still contains only pure, natural essential oils, it will not have the properties you want and expect. Asking for an oil by its Latin name may help, but it doesn't guarantee that you will get what you want.
How to Buy Essential OilsAt first, it may seem a formidable task to detect the difference between good and poor grades of oil or to spot a synthetic. But you'll be pleasantly surprised at how easy it becomes, after only a little practice, to sniff out good essential oils.
Until your nose knows, you'll have to trust your source. Each essential oil company decides the quality it will offer. Some companies consistently sell the poorer, cheaper grades while others prefer to sell the higher grades. They will rarely offer you, as a retail consumer, a choice in grades. As a result, some lines tend to be more expensive than others. But do not use price alone to judge an oil's quality, since lower grades of oil may be sold for far more than they are worth. Remember, too, that store clerks do not always know much about aromatherapy and may naively think that anything labeled an essential oil comes from the plant named.
Cheaper essential oils may actually end up costing you more
money in the end because they are weaker and you might have
to use more to achieve the same effect.
Sophisticated advertising and fancy packaging may also be misleading. And, because not everyone cares about the healing effects, a few companies have filled the growing demand for scents with the cheapest means at their disposal. The most unscrupulous will sell low quality oils for the price of better ones.
This being said, you will find oils and related supplies at natural food stores, herb stores, specialty mail-order catalogs, and of course, at aromatherapy and skin care outlets. Some stores also have retail sites on the Internet.
Some essential oil mail-order companies are run by aromatherapists who stake their reputation on supplying high quality oils, so they may be the best way for you to get what you want. However, you need to know exactly what you want since you will not have the opportunity to sniff before purchase.
There is great variation in the price of essential oils because some are more expensive to produce. In Bulgaria, schoolgirls labor in the misty morning, picking delicate rose petals just before the hot rays of the sun can release the fragrant oils into the air. Bulgaria produces the world's finest rose oil, but it takes about 600 pounds of petals to make a single ounce of oil! Rose oil also is expensive because the flowers must be carefully cultivated, pruned, and hand-picked.
Jasmine oil is expensive for similar reasons. Producing an ounce of pure jasmine requires 20 days labor for an experienced picker, followed by costly methods of extraction. As a result, rose and jasmine demand top dollar. On the other hand, peppermint is much less costly because the plant contains more essential oil, is relatively easy to grow and tend, and is harvested with machinery. The price of essential oils varies from $5 to an incredible $800 an ounce or more, reflecting the difficulty involved in their production.
Many other factors, such as difficult growing conditions, the rarity of the plant, or where the plant is grown, affect essential oil prices. Essential oils produced in the United States automatically demand a higher price to cover the greater costs of labor.
Surprisingly, cheaper oils will probably end up costing you more in the long run. Lesser quality oils are often weaker than high quality ones, and you will have to use more of them to achieve the same effect as a smaller amount of the high quality oil. Depending on how much more you have to use, you may end up spending more than if you'd simply purchased the better quality oil to begin with.
How to Store Essential OilsOnce you've purchased quality essential oils, you certainly will want to keep them that way. Store them in glass containers. Some essential oils can actually dissolve plastic, and storing them even temporarily in it may contaminate the oil. Don't store essential oils in dropper bottles either, as it doesn't take long for the rubber seals and squeeze bulbs to melt into a gooey mess.
The color of the bottle doesn't really matter. Just be sure to keep all essential oils out of direct sunlight and away from heat so they don't lose their potency.
Essential oils are natural preservatives and will help preserve your carrier oils. Their scent will change and fade over time, however, and eventually lose its quality. Properly stored, most oils will keep for at least several years. The citrus oils, such as orange and lemon, are most vulnerable to losing their smell, but even they will keep for a couple of years if refrigerated.
A few essential oils, including patchouli, clary sage, benzoin, vetiver, and sandalwood, actually help fix the scent of other aromas combined with them. And they get better with age. The same is true for thick resins such as myrrh. Patchouli that has been stored for many years smells so rich, few people recognize it -- even those who otherwise dislike it! Essential oils such as these become yet more valuable with age.