Methods of Extraction and Production of Essential Oils
How are Essential Oils Produced - How To Extract Lavender Oil?Essential Oils may be produced by several different methods. The primary methods of extraction of the volatile oil are steam distillation, expression and maceration. There is also solvent extraction methods. Each of these methods will be looked at below.
What is the Steam Distillation Process?
The Steam Distillation process of extracting essential oils involves placing quantities of plant materials in a large container of water. This water and plant mixture is then brought to a boil and steam is produced. Distilling Lavender oil is the preferred method for Lavender oil extraction.
In Lavender oil distillation the essential volatile plant oils are carried by the steam through a cooler (the coil) where it condenses. This liquid made up of plant oils and water is collected. The essential oils are floating on top of the water in a thin film and must be separated.
Not all of the produced essential oils can be captured from the liquid. The water and oil that remains after the process is finished is known as a hydrosol. Do not confuse it with a floral water. True hydrosols are the resultant byproduct that comes from the steam distillation process.
This method is used for distilling Lavender as well as many other plants. Learn more about making Lavender essential oil at home using this distillation process for Lavender oil production.
The Expression Method
Essential Oils can be produced or extracted using the Expression method. This method is used for those plant materials that contain essential oils in larger oil sacs. The plant oils are squeezed from the plant materials and collected for use and filtered. Citrus fruit essential oils such as orange, lemon, lime are examples of the types of plant materials where the expression method is used as a means of extraction.
What is Maceration?Maceration is used as a means of extraction of plant essences. This method does not produce pure essential oils but rather 'carrier oils' which "carry" the plant essential oils along with them wherever they are applied.
In the maceration method of extraction quantities of plant materials are collected and chopped. This plant material is placed into a a container of another oil such as olive or sunflower oil. This mixture is then allowed to sit for a period of time and agitated and mixed periodically.
After some time has passed the macerated plant material is removed and the oil is filtered and strained of any remaining plant particles. The resulting oil is now infused with and contains the plant's essential oil molecules.
Have you ever made rosemary or basil flavored olive oil by placing leaves into a bottle of oil? This is the maceration method only on a much smaller scale. Learn how to make Lavender oil at home with this simple recipe.
Examples of plants using the maceration method of extraction are Calendula, Carrot, and Hypericum (St. John's Wort.)
Solvent Extraction Methods Explained
Some plants have much smaller oil sacs which means collection and extraction of the plant oil is much more difficult. Some of these flowers and plants are also more fragile and delicate and their fragrances are easily damaged by using the steam distillation method.
These fragile plants that have volatile oil in smaller quantities where it is much harder to extract their fragrance use the solvent extraction method for producing fragrance oil.
In the solvent method the Lavender flowers or other plant material is collected and placed into a rotating drum container along with a chemical solvent. The drum is rotated allowing the mixing and penetration into the materials. The Lavender plant material sits in this solvent (Hexane) and the plant essence, color and plant wax is released. The solvent is allowed to evaporate and leaves a substance which is called concrete. This concrete is made up of the residual plant materials, pigment and fragrant essence.
Alcohol is used to filter away the plant waxes from the oils. To do this the alcohol is distilled away and recycled leaving what is known as an Absolute. The word 'Absolute' will be seen on the bottle of the oils produced using this type of chemical extraction method.
The resulting Lavender essence is not a pure essential oil because there is a 2 - 3% solvent residue in the bottled oil. The absolute is a much more concentrated fragrance than those produced using other methods.
Examples of plants whose oil is extracted using this solvent method of extraction are Rose and Jasmine. This type of extraction may be used for other herbs and plants as well because of the higher concentration of fragrance it is able to capture.