Essential Oil Production Techniques

Essential oils are used in aromatherapy, perfumes, oil and creams and for many other purposes where a nice smell is needed. A number of methods are used in order to extract the essential oils from plant material and flowers. Flowers contain only a small amount of essential oil as a result a considerable number of flowers are needed to make a small quantity of oil. Over 100 pounds might be required to produce an ounce of oil. A number of flowers are also much too delicate to use the straight forward techniques and labor intensive and time consuming techniques must used. Essential oils are usually expensive but they are very strong. Many recipes only use a very small amount so a small bottle may last for a many months or years.

Extraction by Steam Distillation

This method is the usual method for most of the essential oil production. Steam that is under pressure is passed through flowers or other plant material spread on mesh screens in a still. The oils enter the steam which is then passed into a different chamber where it is allowed to cool. On condensing the essential oil floats to the top of the water where it is removed by skimming. The water left behind is referred to as floral water and can also be used as it contains tiny amounts of the essential oil. It can be used for toners and facial mists. Floral water may be used by people who are sensitive to essential oils since it is much less intense.

Solvent Extraction

For plant material or flowers that are too delicate to use steam extraction, solvent extraction is often used. In this method a solvent is repeatedly passed over the flowers on mesh trays. The esential oils, together with some other soluble materials, dissolve in the solvent which is then filtered and then distilled under low pressure to remove the solvent. The resulting material is called concrete which is a waxy solid containing the essential oils and waxes and pigments from the plants. Some more processing is undertaken to extract the waxes and oils from the concrete. The concrete itself can also be used in perfumes and the waxes are used in candle making and in creams and lotions.

Enfleurage

For plants and flowers with extremely low percentages of essential oils, such as jasmine, a different technique needs to be employed. Flowers are soaked in vegetable oil and left for a few days and then replaced by fresh flowers. This process is repeated until the oil becomes saturated with the oils from the plant material. The essential oils are extracted with alcohol from the vegetable oil. On evaporation of the alcohol the pure essential oil is left. This procedure takes a long time and uses a large amount of plant material resulting in very expensive essential oil.

Cold Pressing

Some oils such as citrus, which entail extracting the oil from fruit not plant material, use a system known as cold pressing. In this method the fruit is rolled between spikes which penetrate the skin and then squeeze the fruit to extract the juices which contain the oil. Centrifuging is then used to separate and collect the oil.

Extraction using Carbon Dioxide

In this process carbon dioxide is used to extract the oil. A high pressure is achieved by pumping the gas into a compartment that contains the flowers or plant material. When the pressure is increased the carbon dioxide becomes liquid and acts as a solvent. The carbon dioxide is then allowed into into another chamber and the pressure lowered. The carbon dioxide then vaporises leaving behind the essential oil.

Because no impurities are left behind the essential oil is very pure and has a lovely, fresh aroma. As the temperature used is much lower than that used for steam distillation, essential oil can be obtained from delicate plants and flowers that are ruined by steam distillation.

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