Essential oils are obtained by steam distillation of the aromatic compounds of the plant. The parts of the plant that secrete aromatic molecules (depending on the plant: flowers, leaves, bark, etc.) are placed in a copper or stainless steel tank or still. The steam produced by a boiler is injected into the still and will allow to drive the volatile aromatic molecules of the plant . On leaving the still, the water vapor charged with aromatic compounds in the gaseous state is condensed by cooling in a coil bathed in cold water. The liquid produced is collected in the essencier. This liquid iscomposed of 2 immiscible phases : the essential oil (above because its density is <1) and the distillation water (or hydrosol ). The essential oil is recovered simply by overflow. The hydrosol also has interesting properties and is therefore recovered separately.
The essential oil is a concentrate of aromatic molecules from a plant . An essential oil is said to be "complete" or "integral" when the distiller has collected all the distillation fractions , from the more volatile "head" to the final, heaviest fractions. The distillation time varies from one plant to another and the know-how of the distiller consists, among other things, in knowing how to optimize the various parameters (temperature, pressure, distillation time) to obtain the best quality of oil without denaturing the compounds. .
Likewise the yield of distillation , that is to say the quantity of essential oil that can be obtained with a given quantity of plants, varies enormously from one species to another and has a great influence on the price of the product. essential oil . Some examples: to obtain 1 kg of the corresponding essential oil, approximately :
- 6 to 7 kg of flower buds for the clove
- 50 kg of flowers for Lavandin
- 150 kg of flowers for true Lavender
- 150 to 300 kg of flowers for German Chamomile
- 50 to 500 kg of leaves for Peppermint
- 3500 to 4000 kg of petals for the Damask Rose
- 4000 to 12000 kg of grass for the lemon balm
|Material Safety Data Sheet: Essential oils and citrus essences|
|Aspect||Odour||Assets||Concentration in active ingredients||Solubility||Conservation|
|Liquid more or less fluid or viscous, even pasty, volatile and penetrating feel||Powerful, aromatic, characteristic of essential oil||Aromatic compounds, e.g. terpenes, terpenols, phenols, esters, ketones, aldehydes ...||++++||
Not soluble in water Soluble in oil Soluble in alcohol