How Essential Oils Are Extracted
According to the International Organisation for Standardisation, an essential oil is a ‘product obtained from natural raw material, either by distillation with water and steam, or from citrus fruits by mechanical processing, or by dry distillation. The essential oil is subsequently separated from the aqueous phase by physical means.’
From the point of view of Aromatherapy, it should be added that essential oils must be truly natural, because only genuine oils convey a whole, complex, and complete information from the plant.
The distillation of essential oils and floral waters from plants is one of the oldest skills of humanity. The oldest distillation apparatus from Afghanistan dates back to the year 3000 B.C. The distillation technique was brought to Europe between the 11th and 13th centuries through the intellectual centres founded in Toledo, Spain, and the school of Salerno during the Crusades.
From there the distillation became known in France, in the region of Montpelier. Until the Middle Ages, distillation was performed for the preparation of aromatic waters, the oily layer floating on top of the distillates were often discarded as a by-product!
First distillation of a true essential oil was performed by a Catalonian physician, Arnold de Villanova (1235-1311). Paracelsus, a doctor from the 15th century, called essential oils the ‘quinta essenzia’ of the plant. Between 1500 and 1507, Brunschwig, a physician from Strasbourg, France, published his two famous volumes on distillation entitled ‘Liber de Arte Destillandi’. Since that time, the origin of essential oils from the plant metabolism, and their production by steam distillation process has been described in detail in the literature.
Over the years, the quality criteria have virtually become the standard in areas such as holistic and therapeutic aromatherapy. During all stages of producing a genuine and authentic oil the final goal should be to produce the best possible essential oil. The distillation is carried out as slowly and carefully as possible. Distilling genuine and authentic oils from wild plants additionally requires knowledge to be able to gather only the plants from the one species to be distilled.
Genuine and authentic essential oils should be distilled slowly and at reduced pressure and temperature. A lower distillation temperature protects the essences from being oxidised, and fragile molecules from being destroyed by excessive temperature.
Genuine means absolutely unaltered. This means the addition of even natural substances is not permitted. Genuine essential oil should be:
Authentic means that the oil should reflect the composition of the plant specified on the label. Essential oils should be distilled from plants or their parts that belong only to one clearly identified species.
Analysis shows that the chemical composition of an essential oil is genuinely quite constant within a botanical species. Conditions of climate or harvest effect nuances of its composition, but not to such extent that it becomes an entirely different oil.
Here are the most significant methods used to extract pure essential oils from plants: steam distillation, expression, and extraction. The yield is small, requiring huge amounts of plants. To produce 1kg of lavender, rose and lemon oils requires some 200kg of fresh lavender flowers, between 2,000 and 3,000 kg of rose petals and 3,000 lemons.
Steam distillation involves placing the plant material on a grid inside a distillation vat and passing steam through it under pressure. The heat of the steam causes the cell walls of the plant parts to break open, releasing the essential oil as a vapour. This vapour is passed with the steam through cooling tanks, where it condenses. When the steam and oil vapour are cooled, the essential oil usually floats on the water in the collecting tanks as most of the essential oils are lighter than water. The essential oils then separated out.
Extraction is applied only to citrus oils. The peel of citrus fruits has oil glands containing globules of essential oils, which is pressed from the peel after the pulp has been separated. It is done by machine.
Solvent extraction is used mainly for the finest flowers such as jasmine, rose and neroli. The final products of extraction are called absolutes, concretes and resinoids. The process is an art. The oldest methods are maceration, soaking the plant materials in a vegetable oil, or enfleurage, placing flower petals on purified animal fats.
Solvent extraction is a complex process. Flower petals are placed in a sealed container and a liquid solvent is flowing over the flowers, covering them. The solvent slowly dissolves the essential oils from the petals. The solution is then collected, and the solvent gently distilled off.
Trust you have a better understanding now on how essential oils are made, if you do have any questions on how to extract essential oils please pop them in the comment box below and we’ll try to help out.