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Top 5 Ways to Extract Essential Oils – You Must Know

Today, I will introduce the extraction methods of essential oils:

Cold Pressing

A while ago, in order to drink lemonade, I only needed to use half a lemon. I didn’t want to use the juicer. I squeezed the lemon juice directly with my hand. When I squeezed it with my hand, the essential oil from the lemon peel came to me at the same time as the lemon juice flowed down. After spraying, I immediately remembered the cold pressing method in the aromatherapy book. This is a purely manual cold-pressing method. I also thought of this fresh lemon, there are so many essential oils!

The cold pressing method, as its name implies, is to press directly on the peel to squeeze out the essential oil in the peel.

Usually on the peel of citrus genus Rutaceae, such as sweet orange, lemon, grapefruit, tangerine (tangerine), bergamot, etc., are rich in essential oils, and commercial mass-produced peel essential oils are usually produced at the same time. A lot of juice, so the citrus peels essential oil extracted by cold pressing is cheaper than other essential oils.

Distillation

Distillation extraction is the most commonly heard method, and it is easy to find information in major books.

Distillation can be subdivided into water distillation, and steam distillation.

Water distillation

After crushing the plant material, it is boiled with water. In the closed distillation cylinder, the aromatic substances in the plant evaporate along with the water vapor and flow into the cooling tank with the pipeline. After cooling, it is reduced to liquid and flows into the collecting barrel.

This distillation method is more suitable for plants that are boiled with water and will not be boiled (it can be imagined as boiling soup to boil the essence of plants), such as woody and rhizome plants

Steam distillation

As the name implies, it uses hot water vapor to steam the plant material on the water (think of steamed buns with an electric pot). The volatile components in the plant will be taken away by the water vapor and flow into the pipeline through the pipeline The cooling tank, after cooling, is reduced to liquid and flows into the collection barrel.

This distillation method is suitable for more fragile herbs such as mint and leaf extracts.

After the liquid from the above two distillation methods flows into the collection barrel, the essential oil will float on the water due to its low density, and the lower layer will be pure dew. These two products have now become the products often used in aromatherapy.

Essential oils and hydrosols are distilled by the distillation method because, after heating extraction, the smell of essential oils and hydrosols is sometimes different from the original plants. For example, German chamomile flowers smell of sweet apples and chrysanthemums. After distillation, The essential oil that turns blue smells like a thick herb with a touch of moist air so doesn’t be too surprised to smell the essential oil that is different from the original plant!

Liposuction

This is an ancient and traditional extraction method, which is complicated and labor-intensive. At present, only Grasse, the perfume capital of France, uses this technology to produce perfumes and balms.

Extraction step

Prepare a long glass wooden frame (grease suction frame) and coat it with a layer of grease (usually solid, non-contaminated animal or vegetable oil)
Arrange the fresh flowers one by one on the grease
When the oil has absorbed the aroma of the flowers, replace with a new batch of flowers, if repeated, until the oil has absorbed the aroma of the flowers (this oil is called “Pomade”)
Then, the essential oil in the balsam is extracted with alcohol, and the alcohol is evaporated by low-pressure distillation to obtain “enfleurage absolute”
This method reminds me of the current soaking oil, and the concept is also a bit similar. Soak the plant in vegetable oil, soak it directly, or heat it at a low temperature for extraction, and use the oil to dissolve the essence of the plant, because it has recently entered the pit of handmade soap. , and also started soaking herbal vegetable oil by myself, very fun too!

Because of its high price, liposuction was gradually replaced by the solvent extraction method to be introduced next.

Solvent extraction

In the past, it was very popular to use 95% alcohol to soak the grapefruit peel (other citrus peels can also be used), and the alcohol solution after soaking was used to make dishwashing liquid. I have also tried it 😆, and now that I have learned aromatherapy, I don’t think it is so troublesome, also peeled and soaked, adding lemon essential oil is a time-saving and labor-saving method!

Later, after studying aromatherapy, I learned that the alcohol solution obtained in this way is called “tincture”. Maintenance and drinking; traditionally, sorghum wine is also used to soak traditional Chinese medicine, also known as “medicine wine”, and it is also a kind of tincture.

Solvent extraction is a gentle and meticulous extraction method, because it has a relatively low degree of damage to essential oils, and is usually used on aromatic plants that cannot be distilled, such as:

  • Unheatable Plant, ex Moroccan Rose
  • Plants with low oil content, ex Chiba roses
  • Contains resinous plant, ex benzoin
  • The essential oils obtained by solvent extraction have a strong aroma, and even non-volatile substances (such as vegetable waxes and vegetable pigments) are also extracted with the essential oils.

Extraction step

Place aromatic plants in airtight containers with organic solvents (such as ether, hexane, toluene, formaldehyde, acetaldehyde, alcohol, etc.)
The solvent dissolves plant matter including essential oils, plant waxes, resins, plant pigments
Then place the aromatic solvent in a vacuum steamer to evaporate the solvent to obtain a waxy “concrete”
Use alcohol to extract the essential oil components in the condensed body, remove the wax, and then volatilize the alcohol to get the “absolute”
The aroma of the original essence is very close to the aroma of the original plant, but no matter how the solvent is evaporated, there will still be a little organic solvent left in the original essence. Please pay attention to low-dose use, as it may cause skin irritation.

Supercritical carbon dioxide extraction

CO2 extraction machine
CO2 extraction machine

At medium temperature and high pressure, carbon dioxide will reach a critical point, appear in the state of liquid and gaseous supercritical fluid, and become a medium with high solubility, so it can extract plant essential oils and other components.

Extraction step

Put the plants in a closed high-pressure reaction tank

Carbon dioxide supercritical fluid passes through plants, bringing out the aromatic molecules and essence of plants
Reduce the pressure, let the carbon dioxide change back to a gas, and get pure CO2 essential oil
This extraction method has several advantages:

  • The aromatic molecules are complete, and not damaged by high temperatures, and it is easy to obtain the complete components of the plant
  • Short extraction time and high oil extraction
  • Carbon dioxide does not easily react chemically with the aromatic molecules of essential oils
  • The smell of essential oils is close to the original plant smell.

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