The Extraction of Essential Oils
This is the most common process of extraction and method which was used in ancient times. The method uses hot water or steam. The plants are contained in a large tank or vat. Steam is sent through the plants from the bottom of the vat, the steam breaks open the cell walls and evaporate the essence or essential oils. The steam, containing the evaporated essences is passed through a pipe or coil which is cooled with running water and the steam is condensed. The mixture of condensed water and essential oils separates naturally and the essential oil are then bottled. The remaining “floral” water is often used as an ingredient for cosmetics.
This is an extraction by fats. This is the method used for delicate petal flowers as Rose and Jasmine. Sheets of glass are coated with fat, usually purified lard or an oil-soaked fabric. Freshly picked petals are sprinkled over the fat. As the petals fade, they are removed and fresh ones are spread over the fat. This can take many days, sometimes up to three weeks until the fat is saturated with the essence.
The fat is collected and any debris such as stalks or petals are removed. It is now called a “pomade”. This is then diluted in alcohol and shaken vigorously to separate the fat from the essential oils. By further processing, the alcohol is removed.
This is mainly for the oils from citrus fruits such as oranges, lemons, tangerines, etc. The natural peels of the fruit are pressed which releases essential oils.
This is a relatively modern technique. Plants are immersed in a solvent such as petrol ether or acetone and are separated either chemically or by distillation at a temperature that condenses the oil but not the solvents. Such oils usually contain some small amounts of solvents and are not suitable for Aromatherapy.