Essential Oil Extraction Processes - Solvent Extraction

Some plant material cannot tolerate the heated forms of extraction such as steam distillation. High heat damages these plants and once damaged, their essential oils too are damaged and are no longer able to be extracted. For these plants, as well as others, solvents such as ether, ethanol, methanol, hexane, alcohol and petroleum are used instead. The problem with using solvents to extract essential oils is that most of the time, residual solvents or impurities remain in the end product. Because they're impure, those true to aromatherapy refuse to use them. 

As mentioned above, there are times when solvent extraction makes sense. This process involves a lot of chemistry and is somewhat confusing to understand but in general it is as follows.

Plant material is first washed in a bath of hydrocarbon solvents. This process dissolves the necessary plant materials including the aromatic molecules, waxy matter and pigment and the dissolved matter mixes in with the solvent. The solvent mixture is then filtered and distilled using low pressure. After distillation and further processing, either a resin or a concentrated concrete remain. Additional processing using alcohol helps extract the essential oils.

This is a very fast and cost-effective method of essential oil extraction, but there is a downside. With solvent extraction, residual solvents remain and their presence can cause problems if used by individuals with allergies or sensitive skin. That's another reason why essential oils extracted using solvents are used in the manufacturing of perfumes and fragrances, not in aromatherapy or skin care products.

Super Critical Carbon Dioxide (CO2) Extraction

The end result of super critical carbon dioxide (CO2)