Supercritical carbon dioxide (CO2) fluid extraction is a relatively new, environmentally friendly and highly efficient extraction technology. It produces superior herbal extracts widely used in the food, natural flavoring, fragrance and herbal medicine industries.
CO2 extraction can be selective – it can be employed to isolate and remove an undesired compound as in decaffeination, or to concentrate an exciting array of aromatic molecules in volatile form.
Many but not all CO2 extracts can be used in the same way as steam distilled essential oils for aromatherapy and natural perfumery.
Some CO2 extracts are solid or semi-solid at room temperature and are therefore not recommended for use in a diffuser.
The main distinction between CO2 extraction and steam distillation is that CO2 is used as the solvent instead of superheated water or steam. The extraction process begins by pumping pressurized CO2 into a chamber filled with raw plant material. When CO2 is subjected to pressure it becomes ‘supercritical’ and has liquid properties while remaining in a gaseous state.
Because of the liquid properties of the gas, the CO2 functions as a solvent, pulling the volatiles and other substances such as pigments, waxes and resins from the plant matter.
CO2 is the “supercritical solvent of choice in the extraction of flavor and fragrance compounds, since it is an odorless, colorless, highly pure, safe, cost effective, nontoxic, nonflammable and recyclable gas allowing supercritical operation at relatively low pressures and near room temperature.”
The temperature involved in CO2 extraction is between 95 to 100F degrees compared to 140 to 212F degrees in steam distillation. It is likely that steam distillation has been considered the best method to obtain essential oils because CO2 extracts were not available in the early 1990s, when aromatherapy was gaining popularity and being written about.
However, steam distillation produces variation in oil quality depending on the temperature, pressure and time parameters set for distillation.
The CO2 supercritical extraction process will, in some cases, produce a superior oil that has not been altered by the high heat associated with steam distillation. In this way, CO2 extracts more closely resemble the plant’s original chemical makeup, and contain a broader spectrum of constituents than is found in their corresponding essential oils.
When examined, we find that heat is a great potentiator of chemical reactions. In steam distillation of essential oils, the temperature involved in the process changes the molecular composition of the essential oil.
One excellent case in point is that of German (Blue) Chamomile (Matricaria recutita) where, during distillation, the matricin component of the oil changes to chamazulene upon exposure to high temperatures during steam distillation. At the end of distillation of German Chamomile, the matricin has been lost and chamazulene has been formed. The blue color of German Chamomile oil is evidence of this chemical change, as chamazulene is a rich, dark blue.
However, when German Chamomile flowers are extracted using CO2 technology, the resulting extract is green. The chemical reaction due to exposure to heat does not occur, thus the extract is more similar in chemical composition to the original flowers than the distilled essential oils.
We recognize the many considerations involved in the selection of essential oils and extracts; while we consider some CO2 extracts to be superior to steam distilled essential oils aromatically, we do not believe this is always the case.
For example, when extracted with CO2 technology, spice oils such as Cinnamon, Cardamom and Clove are, in general, aromatically incomparable to typical steam distilled spice oils – the CO2 extracts are generally more complex, vibrant and alive. This is not necessarily the case with all essential oils and their corresponding CO2 extracts.
Steam distilled Patchouli essential oils and Patchouli CO2 extracts are significantly different, with very distinct aromatic profiles. In these cases, some people will prefer the more earthy and musky steam distilled Patchoulis to the fresher, greener, more refined aroma of Patchouli CO2 extracts.
Ultimately, in the case of any oil or extract, it comes down to personal preference, and it is not accurate to say that one is better than the other.
Eden Botanicals was one of the first essential oils companies in the US to embrace the use of CO2 extracts in aromatherapy and natural perfumery. In order to provide the widest variety of superior quality aromatics, we offer many of these specialty CO2 extracts in addition to our exceptional collection of traditional, steam distilled essential oils. In some cases, we offer only the CO2 extract of a botanical due to its extraordinary features.
In summary, the supercritical CO2 extraction process for aromatic herbs yields a wider range of compounds while reducing heat degradation. This method eliminates the need for solvents like hexane, used in the manufacture of absolutes, while providing pure aromatic oils via a kinder, earth-friendly process.
Eden Botanicals carries a full range of CO2 extracts. Please click here to view a complete list of our CO2 aromatic extracts, and here for the CO2-extracted carrier oils that we offer, including certified organic CO2 extracts.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6270407/ https://academicjournals.org/journal/AJPP/article-full-text-pdf/32F09D233288 https://en.wikipedia.org/wiki/Supercritical_carbon_dioxide https://en.wikipedia.org/wiki/Matricin