Extraction Of Essential Oils
There are five methods of extracting essential oils. They are:
- Distillation
- Maceration
- Solvent extraction
- Enfleurage
- Expression
Distillation:
In this method raw material and some water is put into large clay pot. The neck of the pot is covered with cotton. Heat is then applied and the steam that is formed pass through the layers of cotton before escaping. The essential oils are trapped in this material. Then they are squeezed out of them.
In modern methods, the plant is heated with water or with steam or both in a vessel called a still and channeling the vapour thus produced into a condenser. The heat from the steam causes globules of oil in the plant to burst.
The liquid produced consist of mixture of oil and water and the oil floating on water or heavier oil like clove oil sinking to the bottom. It is then easy to separate the oil from the water. Hence the essential oil is obtained.
Maceration:
This is a process employed for plants which do not generate essential oils after harvesting. The flowers are put into a container of hot fat which penetrates the cells and absorbs their essential oils.
The flowers are then removed by straining and more fresh flowers put back into the hot fat. This process is repeated 15 times and the resultant pomade is washed by alcohol.
Solvent extraction:
It is applied to the gums and resins and flowers. The material is placed in a vessel and is covered with the solvent. The mixture is then heated slowly, during which the solvent extracts the odorifereous principle of the material.
This is then filtered, which results in the production of a dark colored paste which is called ‘concrete’. This contains both natural wax and the odorifereous matter. The mixture is then washed several times in warm alcohol to produce the most concentrated form of natural perfume known as ‘absolute’.
Enfleurage:
This method is used for extracting essential oil from flowers like the jasmine which generate essential oils after they have been harvested.
A sheet of glass is mounted on a rectangular flame called ‘chassis’ and a thin layer of fat is spread on both sides of the glass. Fresh flower petals are spread on the fat and another chassis is placed on top of it so that the flowers are caught between the two chassis.
After a day the flowers will have given up all their oils to fat. The withered flowers are replaced by fresh ones every day until the right concentration is obtained. When the fat is completely saturated with perfume, the extract is obtained by the help of several washings of alcohol.
Expression:
This process is used to extract citrus essences like lemon, orange, grape fruit, etc. The oil is squeezed onto a sponge and when the sponge is saturated, oil is squeezed out. The fruits are rolled around in hollow containers which have spikes on their walls which puncture the fruits and liquid flows down in another container.