- Essential Oil Extraction
Essential oils are the concentrated essence of the plant. They are extracted from varied parts of the plant such as the root, seed, trunk, leaf, fruit or flower. Each essential oil has a unique chemical composition consisting of botanical vitamins, hormones and antiseptics. Escents has leaned about the properties of the many available essential oils to make them available to treat a wide range of conditions, from headaches and muscular pains to depression, insomnia and stress. The method used to extract each essential oil varies based on the part of the plant from which its derived, and is intended to maximize the potency and benefits found in each drop of oil. The following are the basic extraction methods used to produce therapeutic grade essential oils:
True essential oils are those that are extracted through steam distillation. This is where the plant material is placed on a grid with hot water underneath. The steam draws out the essential oils from the plant material. These tiny molecules evaporate with the water and then go through a cooling system where they end up back in liquid form. Here the essential oils are either floating on top of the water or settled on the bottom depending on the density of the oil. Then the essential oils are separated from the water, leaving the floral waters, called hydrosols, which still retain some of the therapeutic properties. This form of extraction is the most common method for most essential oils.
Citrus oils are extracted through expression or cold pressing. Here, the rind of the fruit is pressed between two blocks of wood with one side having a sponge. The little sacs are squeezed so that the essential oils saturate the sponge. The essential oil or essence is then squeezed out of the sponge. Often rind particles find their way into the essential oils and it is not uncommon to see floating bits or sediment. When this process is used, the proper name for the resulting liquid is an "essence"; however, most people simply refer to the liquid as essential oils.
Solvent Extraction - Resinoids
Resins are the solid or semi-solid substances exuded from the bark of trees or bushes when wounded. The gum-like substance produced does not exist in the tree beforehand but is produced pathologically, solely as a result of the incision, and hardens on exposure to air. Various solvents can be used to extract the aromatic molecules from the resins; the most frequently used being hydrocarbons (e.g. benzene, hexane) or alcohols, with each solvent type extracting different molecules. The solvents are filtered off and afterwards removed by distillation to leave either resinoids (from hydrocarbon solvents) or absolute resins (from alcohol solvents).
Solvent Extraction Concretes
The extraction of concretes is similar to that of resinoids; hydrocarbons are used as solvents. For concretes however, plant material (leaves, flowers, roots, etc.) is used instead of resin this is the main difference. Most concretes are solid wax-like substances and are often used in food flavourings.
Solvent Extraction Absolutes
An absolute is prepared from a concrete, by adding an alcohol to extract the aromatic (alcohol-soluble) molecules. The alcohol is then evaporated off gently under a vacuum, leaving the absolute, which is a thick, coloured liquid. The absolute method is typically used for are and very delicate flower petals because steam distillation is too harsh, and no essential oils can usually be derived from such delicate petals. Absolutes of jasmine, tuberose and vanilla are achieved using this process
Absolutes and resins are much used in the perfumery world, and although they can be useful in some applications of aromatherapy, it must be appreciated that they always retain a small percentage of the solvents used in their production. Luckily, very small quantities of the absolute are used for each aromatherapy application so the risk is negligible.
CO2 extractions are made using high technology equipment where carbon dioxide gas, high pressure and low temperatures are used to extract the essences. This process produces oil that retains greater amounts of aromatic components than by steam distillation. The scent is therefore more identical to that of the original plant. This process makes it possible to have scents not attainable by usual extraction methods (like papaya, mango and black current). The CO2 is used in a gaseous form and naturally evaporates or dissipates, leaving behind no residue.