Essential oils are the quintessential part of a plant or fruit. They are the aromatic compound stored in each plant that gives the plant its unique characteristic. Essential oils can be extracted from almost any plant material – this includes grasses, leaves, flowers, twigs, peels, seeds, bark and roots. Essential oils are also unique in a sense that the same tree can produce different essential oils depending on the extraction location. Take the orange tree for example, Neroli essential oil is extracted from the flowers of the orange tree, while Petitgrain essential oil is extracted from the leaves of the same tree.
There are a many ways of extracting essential oils, some still extract essential oils traditionally by hand while others use machines to help with large scale extractions, but the most common three ways of extracting essential oils are: steam distillation, solvent extraction and expression.
This technique uses steam to collect essential oils from the plant. Raw plant material are placed in a large funnel, and steam is passed through the funnel causing the plant material to release their aromatic compounds. The aromatic compounds then vaporize and rise with water vapor into a cooling system above the steaming chamber. As the plant vapor cools and condenses, the vapor turns into liquid and travels into a separator. Water from the steam will be separated at the bottom while the oil will float above the water. This oil will be decanted off and become what we call: essential oil.
Solvent extraction is best suited for plant materials that yield low amounts of essential oils, namely, Rose and Jasmine. These essential oils are also largely resinous, and have a low tolerance to pressure and the distress of steam distillation. Through solvent extraction, plant material are treated in a solvent to extract and remove the wax and pigments. Once the plant material has been treated with the solvent, it produces a waxy concrete compound. To release the essential oils from this concrete compound, alcohol is mixed into the substance, causing the oil particles to be released. These oil particles are also known as absolutes.
Expression, or cold-pressing, usually applies to the extraction of essential oils from citrus fruits like grapefruit, lemon and orange. By using this method, the fruits are placed in a container with spikes that will puncture the peel while the spiked device rotates. This puncturing will cause the essential oil sacs on the underside of the rind to rupture. The fruits are then carried to the collection chamber where they are pressed further to juice out all the liquids and oils. At the last stage, the oil and juice are put into a machine that uses centrifugal force to separate the essential oil from the fruit juice.
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