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Thursday, August 6, 2009

The Extraction of Essential Oils by Hydro-Diffusion (Percolation) and Carbon Dioxide Extraction


Photo of a Simple Homemade Still


As discussed in the post The Extraction of Essential Oils by Distillation and Expression, there are now new methods of extracting some essential oils. Both hydro-diffusion and carbon dioxide extraction are new methods, and there are some essential essential oils for sale which will be described as, for example, 'CO 2 extracted'. Although distillation of essential oils remains the most popular and most frequently used method of extracting essential oils, it is worth mentioning the two newer methods of hydro-diffusion and carbon dioxide.



- Hydro-Diffusion Extraction (also known as percolation) - is the newer of these two extraction methods for essential oils. It is quicker than distilling an essential oil and works much like the process of a coffee percolator (hence its alternative name of percolation). As it is a fairly new procedure for extracting essential oils, it is not known yet whether essential oils obtained through hydro-diffusion extraction is of the same quality as those obtained through distillation. Additionally, not all essential oils, are suitable for hydro-diffusion.



- Carbon Dioxide Extraction - as the name suggests, carbon dioxide extraction uses carbon dioxide to extract essential oils. It is an expensive method of extracting essential oils, using both high pressure and low temperature to extract the essential oil from the plant material. It is said that carbon dioxide extraction produces an essential oil which is closer to the essential oil present in the plant (remember that the 'essential oil' obtained through distillation is not the same as the essential oil present in the plant; chemical components are 'altered' through the extraction process). Carbon dioxide extraction does not leave a trace of carbon dioxide in the resulting essential oil and essential oil suppliers are marketing these essential oils as 'pure'; however, the essential oils obtained through carbon dioxide extraction are usually more expensive.



Personally, I have traditionally used distilled or expressed essential oils for pure aromatherapy use - until now. If research continues into the newer methods of hydro-diffusion and carbon dioxide extraction and I am convinced these essential oils are also pure, and can be bought at a reasonable price, I may consider using them in the future...

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