Western countries have long been committed to the extraction of aromatic plant essential oils. According to records, as early as in ancient Rome, the extraction of essential oils began by soaking; around 1000 AD, the Arabs began to distill the rose essential oil with steam, which became the perfume center of the world at that time. To date, many methods have been developed for extracting essential oils.

Steam distillation

The steaming method is one of the earliest methods of refining. With the changes of the times, the instruments used have been significantly improved, but the principle is basically the same: the aromatic plants are placed in a distillation vessel, and high-temperature steam is introduced into them. Or put the spices and water together to boil), at this time, the essential oil containing the aromatic components in the plant will diffuse into the water vapor to form an azeotrope of oil and water; thereafter, the azeotrope is cooled, because the oil is insoluble The water, which separates from the water, forms the essential oil we need.

The distillation method is very convenient and does not require the use of chemical solvents, so the current application is still very common. Roses, lavender, rosemary, geranium, etc. are mostly used in this way.

Pressing method (extrusion method)

By cutting, pulverizing, and extruding, the water of the plant and the essential oil containing the aromatic component are separated from the raw material to obtain a mixture of water and oil, and then the oil and water are separated by centrifugation, filtration, etc., and an essential oil is obtained.

In the past, this traditional method of extracting essential oils in the general household is not only simple and convenient, but also ensures that the natural components of the essential oils are not destroyed during the extraction process.

Plants such as citrus, lemon, bergamot, and lime will become odorous in the high temperature of water vapor, and it is not suitable to use steam distillation, so most of them are used.

Fat absorption method (fat cold suction method)

The general method is: put a layer of lukewarm fat (used with butter or lard) in several flat-bottomed glass pots (or ceramic pots), spread the fresh petals on the fat; Spread the fat; then pour the layers of the glass, so that the petals are pressed between the two layers of fat, and the oil can be absorbed by the fat. So change the petals every one or two days. Until the fat reaches saturation. Finally, the fat is separated and the essential oil is obtained.

This method is commonly used to extract essential oils such as jasmine, rose, and orange blossom.

The suction method is a very old method for extracting aromatic essential oils in southern France. It is also the most expensive method because it takes a lot of manpower and time.

Soaking method (oil temperature immersion method)

This method is similar to the lipid absorption method, but it is easier to operate by changing to liquid fat:

The plant material (petal or resin, etc.) is placed in a liquid fat, heated and maintained at a temperature of 60 to 70 degrees, and the aromatic component of the raw material is released into the liquid fat. The liquid grease is then separated by filtration to obtain an essential oil. .

This method can be used for frankincense, myrrh, sandalwood, and the like.

Extraction method (dissolution method)

The liquid solvent such as alcohol or petroleum ether is thoroughly mixed with the plant material, and the aromatic components in the raw material, as well as the vegetable wax and the pigment, are dissolved and released into the solvent; and then the solvent is separated from the liquid mixture to obtain a fragrance. An extract of ingredients, plant waxes, pigments, etc.; finally, the extract is purified to obtain an essential oil.

This method is commonly used to extract essential oils from plants such as cinnamon, sage, and benzoin.

"supercritical carbon dioxide" extraction

The principle is that the density of carbon dioxide under high pressure or low temperature is close to liquid, while retaining some properties of ordinary gas, which is called "supercritical fluid", which has strong solvency. When the spice plants come into contact with it, the aromatic components of the plant dissolve in the fluid. The aromatic component can then be finally separated by means of reduced pressure or elevated temperature.

This is a new method that has emerged internationally in recent years. The method can make the extraction of the essential oil can be carried out under normal temperature conditions, and does not need to use a solvent harmful to the human body, can better protect the natural activity of the product, and is a relatively advanced "green separation technology". (Traditional steam distillation, pressing, leaching and other separation methods have some shortcomings in the process, such as the natural active ingredients are vulnerable to damage, and the organic products that may be harmful to the human body may be left in the final product.) However, the current cost of this method is still high and has not been widely applied.

Source: Tuzen Culture