Essential oils are the volatile oils that are extracted from leaves, roots, bark, flowers, heartwood, resin or fruits of a plant. There are several methods for creating essential oils, including:
- Enfleurage: In this labor-intensive method, fresh flower petals are placed in a odorless fat or oil to allow the scent essence to transfer to the oil over several days or weeks. The petals would be replaced several times until the correct scent is achieved. The flowers were removed and the remaining mixture, called ‘enfleurage pomade’ was mixed with alcohol to separate the essential oil from the fat. The final product is called “pomade.”
- Expression: For this method, plant material is crushed to separate the oils from the plant. This method is primarily used to extract the oils from the rinds of citrus fruits such as orange or lime.
- Maceration: Dried or fresh plant materials are ground or crushed and then steeped in a heated oil or fat to draw out the essential oils from the plant. The final product is considered to be a ‘carrier oil’ and not a true essential oil.
- Solvent Extraction: This method is primarily used to create essential oils from plants that have less volatile oils, which make it difficult extract with steam distillation. The plant material is placed in a rotating drum with a solvent, usually a petrochemical, to extract the oils. It is often used to create gums and resins.
- Steam Distillation: Fresh or dried plant materials are boiled in water. The resulting steam is captured by a coiled metal tube for cooling. The resulting mixture of essential oils and water are carefully separated. It is impossible to remove all of the essential oils. The resulting mixture is called ‘hydrosol.’