It’s a well-known fact that most corporations look only for profit. So they tend to use the cheapest essential oils extraction methods. But that doesn’t mean we have to accept any type of product we find in our way just because it’s cheaper.
In this article we will explore a bit this side of making essential oils. Also, see which essential oils extraction methods give the best oils for our health and well-being. Why and what methods companies prefer to use for the extraction of essential oils will also shed some light on how to choose your products.
Technically speaking, there is only one method to get pure essential oils called distillation. And there’s another one to make carrier oils called expression. But with the help of technology, other extraction methods, such as CO2 or hydro diffusion have been developed.
Some methods are able to give really high quality essential oils. They are called “absolutes” and of course their price is also high. That’s why they’re hard to find on the essential oils market.
But let’s see what these essential oils extraction methods are. I believe they’re important to know so you can complete the chapter of essential oils safety.
There are 3 main extraction categories: Distillation, Solvent Extraction and Expression.
The First Category of Essential Oils Extraction Methods is Distillation
Distillation is the process of turning a liquid into vapors through condensation. Condensation is the droplets resulted from the contact of hot steam with a cold surface. At the same time it purifies the resulting liquid as well.
The following factors can influence the quality of an essential oil:
- Harvesting the plant when it’s mature enough.
- Using just the right temperature and pressure.
- Using enough time for all oils and compounds to be extracted.
Water distillation is the simplest of the essential oils extraction methods. It is most often used to extract the essential oils from flowers. Thus, the flowers are immersed into the water. The water keeps them from clumping and help better extract the oils.
The water is heated and the plant material becomes soft. This way the oil molecules are being released more easily.
The steam containing the oil vapors rises and travels till the condenser where it gets cooled off. The steam becomes water and the vapors become oil. This is where they get separated into 2 different products:
- The water becomes hydrosol (hydrolate).
- And the oil goes into its own recipient of essential oil.
Water distillation is a great essential oil extraction method for powdered materials like cinnamon bark. The bark is full of mucilage, and through the use of other methods it would clump. Clumping would make it impossible for the oil to be made.
Water distillation is inexpensive and easy to set up. But it doesn’t completely extract all the oil vapors. Some plants and herbs are difficult to process by their own nature. That’s when this method is most useful to extract their essential oils.
Combination of Water and Steam Distillation
This is the next step after the water distillation. The same tools and recipients are used and it doesn’t cost a lot more than a water distillation. The only difference is that the plants are now placed above the boiling water. And that they’re placed on a perforated metal plate.
This essential oil extraction method is able to make quality oils even though the still is stuffed with plants. The process consists of inserting live steam into the water full of immersed plants.
Sometimes, during the distillation process, the water inside the still may run out. When that happens, producers will manually introduce in the still a cohobation tube. Its role will be to refill the water to finish the distillation process.
This is one of the essential oils extraction methods that refer only to herbs and their leaves.
The Cohobation Method
This essential oil extraction method is used to aid the water and steam distillation processes. Some plant compounds get separated from the oil, especially when they use one of the above mentioned essential oils extraction methods.
They dissolve into the resulting water and in order not to waste them; the water must be distilled again. The purpose is to add the remaining compounds back where they belong. That is back into the essential oil that has just been extracted.
The only condition for this method to work is to keep the temperature below 100° C. The plants don’t have to go into direct contact with the fire to make sure the oils are not ruined.
The downside of this method is that the steam soaks the plants. That makes it harder for the distillation process to start again. Plants need to be dried to keep condensing into the still.
This is another essential oils extraction method that uses steam generated in a separate recipient called a boiler. The plants are held above the steam inlet and distilled. The quantity of steam is controlled from outside. So the oils are safe from being ruined by high temperatures.
To get good quality essential oils a producer needs a temperature below 100° C and little pressure.
Time also plays an important role in the quality of essential oils. If a certain plant needs, for example 48 hours to be drained completely and gets only 40 hours, then the essential oil is incomplete. Thus, its properties and benefits are altered.
This extraction method is superior to the water and water & steam distillation methods. In the industry and business of producing essential oils, fragrances and flavors this method is widely used.
But it is also expensive. The necessary equipment to extract essential oils through this technique costs a lot. And the prices of EOs are not high enough to cover the producers’ expenses. That’s why some choose to use less expensive essential oils extraction methods and sell low quality essential oils.
The hydro distillation method is used to extract the essential oils from resins. Example: Frankincense and Myrrh.
The resins and any other plant materials are immersed into the water brought to a boil. Steam is then introduced in the boiling chamber. The mixture of vapors contains water and oils and resinous gases.
This mixture is then condensed when it gets in contact with cool water. From the condenser, the oil separates immediately from the condensed water.
Hydro diffusion is also known as percolation (the process of going through a filter). And it is almost the same as the steam distillation. The only difference is the way the steam is introduced in the boiling chamber. And the fact that through hydro diffusion the diffusion goes through the plant membranes.
In a steam distillation, the steam is introduced from the bottom. But in a hydro diffusion, the steam is introduced from the top, right through the plants and herbs.
The mixture of steam and oil is found below the grill that holds the plants in one place.
- Uses less steam.
- Takes less time to extract the essential oils (from powdered plants)*
- Gives a better oil yield.
*Whole plants take longer to process with this method.
This extraction method is used to distill petroleum and derivatives. It can also be used to purify the essential oils. The purification happens when the oils get separated in different batches (fractions), at different boiling points. That means the oil is no longer collected in a continuous manner.
This is one of the essential oils extraction methods used to make Ylang Ylang essential oil.
Rectification of the EO extraction
To rectify means to correct, so we could say this is a correction method. It is used to purify and distillate again certain essential oils that have too many impurities.
This purification can be done either through steam distillation or through a vacuum.
The Second Category of Essential Oils Extraction Methods is the Solvent Extraction
This method uses petroleum ether, di-methylene-chloride, ethanol, methanol, hexane and acetone. They’re solvents soluble in oils, meaning they don’t mix with water. They’re used to separate the essential oils from the plants, herbs, flowers etc.
Solvent = a liquid substance in which another substance has been dissolved to form a solution.
The solvent extraction method is useful in extracting the oils from fragile plants. These fragile plants can’t go through the steam distillation and its heat, because they would be ruined. Ex.: Jasmine, Mimosa, Violet, Narcissus, etc.
There is a risk of finding residues of the solvents in the essential oils. And that’s why some specialists don’t encourage their use in Aromatherapy. But the amount of residue (10 parts per million) found after using hexane is too small to really count.
Plants that undergo a solvent treatment produce what we now call concrete. It’s a very aromatic and waxy compound. It becomes an absolute after being treated with another solvent called ethyl alcohol.
Essential oils extracted with solvents are highly concentrated and have a strong smell. It is close to the real plant’s smell.
Hypercritical CO2 Extraction
CO2 (Carbon Dioxide) becomes hypercritical at 33° C. That means it goes into a state where it is not gas and not liquid either. This substance is not toxic and it doesn’t interact with the extracted essential oils.
All these features make the CO2 one of the best essential oils extraction methods. The CO2 solvent can be removed once the pressure is removed as well. The low temperature doesn’t spoil the oils, so the results will be high quality.
This method can produce great Aromatherapy essential oils. But it is too expensive to produce CO2 extracts on a large scale. To get the hypercritical pressure needed, one would need fancy and expensive equipment.
If you find essential oils that state this extraction method and have a low price, you should be careful. Producers need to sell their products at very high prices to cover their production expenses.
This is one of the latest discoveries of extracting pure essential oils. It uses Florasol, the replacer of the Freon – a refrigerant. This refrigerant is friendly to the environment. And it only needs the room temperature to successfully extract essential oils.
But unfortunately, it uses fluoro-hydrocarbons that can harm the body. They’re too reactive and toxic.
Yet, this essential oils extraction method produces pure essential oils. It keeps their natural properties as close as possible to the plant. It is used in food products and sold to people who don’t use products that have alcohol.
The Third Category of Essential Oils Extraction Methods is the Expression
This method of making essential oils is also known as the cold pressed method. And it’s among the best essential oils extraction methods to get carrier oils and some essential oils too. Carrier oils are not essential oils but they have many therapeutic properties.
They’re used to dilute the essential oils and they’re not toxic. They’re not toxic because of this cold pressed method.
Essential oils evaporate in the atmosphere (they’re volatile). And some of these volatile essential oils must be decomposed first to get a good distillation.
Some essential oils are hard to distill with the usual means. Those are extracted through expression. Or through different other mechanical methods (fruits mostly).
Citrus essential oils (Lemon, Bergamot, Grapefruit, Orange etc.) are best obtained through the expression method.
The fruit rinds are mechanically squeezed by compression. Both the juice and the essential oil from the fruit are washed away toward the centrifuge of the device. There, they both get separated and only one becomes essential oil.
A major concern in producing these essential oils is the amount of pesticides used in the growing of the fruits. Their concentration can increase inside the oils.
Cold pressed or expressed essential oils are the safest. They are also very close to pure oils so use with confidence.
Écuelle à Piquer
A word-by-word translation of this phrase would be “pricking in a deep plate that has no rim”.
In France this method uses some sharp needles to puncture the oil glands of the fruit’s peel. Then they add pressure to squeeze the oils out of the peels. After that, a strong but fine water jet is sprayed on the fruit to collect all the oil. At the same time, all the juice from the squeezing is collected separately.
Then the water gets separated from the oil through a centrifugation process. Much like the one the washing machine is using for the laundry.
The écuelle à piquer method is not a labor intensive job. But it is a very good extraction method for carrier oils.
Simple essential oils extraction methods or more complicated and expensive ones, it doesn’t matter. Companies experiment and use them all to reach their clients and offer them what they need.
The market is full of cheap products. But there are also really good quality Aromatherapy grade essential oils. There are many methods through which they can be obtained and that makes life easier for us. Depending on what you’re looking to achieve, you have a wide variety of essential oils to choose from.
Do you usually take into consideration the extraction method when you’re looking for an essential oil? I used to neglect this aspect when I first started showing an interest in essential oils, but not anymore. Now reading the label of an essential oil is the first thing I do.