Essential Oil and its Extraction Methods
Essential oils contain the life essence of plants. These oils are the highly concentrated aromatic essences of trees, shrubs, herbs, resins, and flowers. They contain all the benefits that protect and maintain the plant, and we can use them to help support the health and well-being of our bodies.
It’s important to know that Essential Oils are extracted from plant materials through various processes and removal methods suited to the specific plant part that contains the oil, and not synthetically manufactured in the labs.
While there are many different safe and effective methods of extracting essential oils, in this blog we will focus on those that commonly used today, which are:
Distillation, Expression, Solvent Extraction, and CO2 Extraction
DISTILLATION PROCESS
This is the oldest, simplest, and the most common method of extracting oils from plant materials. Most essential oils are produced through steam distillation. Other distillation methods are water distillation, and steam and water distillation.
- Steam Distillation
This method was invented around 1000 AD by Avicenna, a Persian alchemist and healer. It has been in practice thousands of years since then, and is still one of the best ways to take freshly harvested plant materials to extract essential oils. Raw plant material, consisting of the flowers, leaves, wood, bark, roots, seeds, or peel are often distilled. Most common essential oils that are results of steam distillation are lavender, peppermint, tea tree oil, patchouli, and eucalyptus. This happens when the steam vaporizes the plant material’s aromatic molecules, which eventually go through a condensation and collection process.
2. Water Distillation
Delicate flowers such as roses and orange blossoms would clump up when introduced to steam distillation, so the most effective method of extraction in this situation is to use Water Distillation. This is where the plant material is submerged in a pure boiling water. The vapor then condenses into oil and water. It is then separated to collect the essential oils. The remaining liquid becomes what we call Hydrosol.
EXPRESSION PROCESS
The expression method is commonly used when we are extracting essential oils from citrus fruits. This method is also known as the "expeller-pressed" or "cold-pressed" method since no heat is needed to extract the essential oil. The modern process of expression involves the use of a device that punctures the citrus peels to effectively collect the oil from citrus rinds. The material is then squeezed or crushed under high mechanical pressure. During this stage, the resulting oil and juices will contain citrus rinds so it’s going to be centrifuged to separate the liquids from the solids. Due to the large quantities of oils extracted from citrus peels and the low cost needed in the production of these oils, most citrus fruit oils are cheaper than most essential oils.
SOLVENT EXTRACTION PROCESS
There are some plant materials that are difficult to extract, such as vanilla, or that are too delicate to survive the process of distillation, like rose petals and jasmine flowers. In these cases, we would use another method called Solvent Extraction. This method utilizes food-grade solvents like hexane and ethanol to separate the essential oils from plant material. Solvent extraction typically produces a finer fragrance than most other extraction methods. Technically, the remaining oil in this method is called an Absolute, not an essential oil. During this process, the plant materials are covered by a solvent and produce a waxy compound called Concrete. The concrete is mixed with alcohol resulting in the extract being evaporated so only the plant oil is left behind. The absolute is soluble in this solvent but the other lipid components are not. After another round of vacuum distillation to remove the solvent, a pure mixture of only absolute remains. Only 1–5 percent of the solvent will remain in the final product.
CO2 EXTRACTION PROCESS
This method is steadily growing in popularity as a more natural method to extract essential oils. This is because the essential oils produced using this method are rendered purer and safer to use. The CO2 Extraction method is done through pressurizing the CO2 until it liquifies. This liquified CO2 will be used as a solvent that will absorb all the essential oils from the plant material. The CO2 is then brought to regular pressure and evaporates back into its gaseous state, while what is left is the resulting oil. Plus, CO2 is colorless, odorless, flavorless, and non-toxic; it won’t impact the essential oil. This method produces great essential oils but these essential oils are also more expensive than the others.
Properly extracting oils from the raw ingredients produced by mother nature is an extremely delicate procedure requiring chemical knowledge, extensive experience of handling plant parts, and proper equipment. Essential oils often become adulterated during this process causing it to become impure, less effective, and possibly even unhealthy for our bodies.
The most important thing to put into consideration when purchasing essential oils is to buy from a trusted supplier. Make sure that they list the method of extraction for the essential oils they are selling and to test their oils if there are presence of adulterated additives.
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