04 Feb Essential oils: How are they extracted?
The first thing you need to know about essential oils is they always come from plants. They are extracted from different parts of the plant – lowers, leaves, twigs and branches, seeds, fruit, cones, bark, wood, root, resin. They are highly volatile compounds that easily evaporate and infuse into the air with their characteristic scents. Essential oils are composed of a complex mixture of chemical families such as Esters, Ketones, Alcohols, Aldehydes, Phenols, Ethers Oxides, Lactones, Terpenes etc.
When extracted, essential oils are in concentrated forms and smell extremely strong. It is believed that essential oils act as protection to plants against harmful insects and diseases, but they also play an important role in the reproduction of those plants by attracting insects to pollinate them. These oils contain the ‘essence’ of the plant, hence the name!
Extraction of Essential Oils
This is the most common method of oil extraction. In Water distillation, the plant material is submerged in water, brought to a boil and the vapour liquified and collected using a water-cooled condenser. Oils like Neroli Oil are water distilled.
Steam distillation occurs when a jet of steam is passed through dry plant material and the vapours are cooled using the same water-cooled condenser method. Some oils that are extracted using steam distillation are Eucalyptus Oil, Tea Tree Oil and Lavender Oil.
This method uses volatile solvents to dissolve the oils into, especially for more delicate raw materials that may be heat damaged by the distillation process. It is also a good way of creating a higher yield of oils such as Jasmine Oil and Rose Oil. Solvents used are hexane or alcohol
This is a form of cold pressing where heat is not required to extract the essential oil. The plant material is compressed to extract the oil from the plant. This is the most common method of extraction for citrus oils such as Sweet Orange Oil.
In this method, carbon dioxide is turned liquid under very high pressure and extremely low temperatures. The raw material, when passed through this, acts as a solvent and the essential oil dissolves into it. When the temperature and pressure return to normal, the liquid CO2 reverts back to gas and leaves the oil extract behind.
These extracts have a larger amount of plant materials including volatile or aromatic material, fatty acids, Phytosterols, and other important plant extracts. The advantage of this method is that there is no contamination, no heat degradation and has the highest yield that the plant can give. It is, however, an expensive process as the machines are large and very expensive. This process is mostly used for high-value oils such as Coffee Oil