Introduction to Methods
Different types of essential oils can be obtained from various plants, but the process of extraction usually depends on numerous factors. The method should never be harmful as to minimize the beneficial properties of the oil itself.
Hydrodistillation is the oldest known method of extracting essential oils from plants. It is still used nowadays in some underdeveloped countries. The plants need to be submerged in water and then heated until the steam gets released. It is best when used on nuts, wood and roots and also when there is a need for powders.
Distillation is probably the most common method of extraction of essential oils. It is based on the principle that heated water produces steam which carries the most volatile chemicals and the required aromatic material. The steam gets chilled by a condenser and the oil can be separated easily as it floats on the hydrosol.
Steam distillation involves using an outside source of steam which is often piped into the distillation unit, using high pressure.
Water & steam distillation
This method is usually used for the distillation of leafy materials from the plants. It cannot be used for nuts, roots, woods and other tougher materials. The method involves placing the material in a basket, suspended over boiling water in order to expose it to the rising steam vapors.
This method is commonly used for certain types of aromatics which are too delicate to be treated with any process of distillation. The material needs to be placed on perforated trays and onto the extracting unit where they are repeatedly washed with a solvent. When the process is over the solution contains both the dissolvable plant material and the solvent used, so it needs to be filtered properly. The low pressure distillation is the method most commonly used for the filtering, so that the solvent can be recovered and used again in the future. When this step of the process is over the volatile oil is contained in a waxy mass referred to as concrete. Further processing removes the waxy mess in order to obtain the essential oil.
Carbon Dioxide Extraction
When exposed to high pressure, CO2 becomes liquid and it can be used as an excellent solvent. It does not involve any solvent residues because CO2 reverts back to its gaseous form at normal pressure. It is much better than steam distillation.
This process involves the machines which are designed to score the rind of various citrus fruits.
Florasols are benign gaseous solvents, and so are phytols. They are used for the extraction below ambient temperatures.