The CO2 (CO2) extraction method of essential oils is often referred to as CO2 extraction or supercritical abbreviation. In short, CO2 extraction is performed by pressurizing carbon dioxide until it becomes a critical point for liquid extraction. The liquid carbon dioxide then acts as a solvent to obtain the natural plant matter and volatile oil content, dissolved in the liquid carbon dioxide. The CO2 is then brought back to natural pressure, the carbon dioxide evaporates back to its gaseous state and the rest is the resulting oil.
This set of "high-pressure, low-temperature" extraction methods began in the 1980s, and its instruments and equipment are very complex and expensive. Its essential oil is labeled "CO2 Extraction." This extraction method is carried out in a closed reaction tank all the time, the time required is very short, just a few minutes (distillation method takes at least 1 hour).
Compared with the solvent extraction method, this extraction method does not have any solvent residue.
Carbon dioxide extracts are usually thicker than distilled essential oils and often smell closer to natural grasses. Carbon dioxide extracts have been said to contain additional components extracted by steam distillation from the same plant. This seems plausible because carbon dioxide extracts are usually thicker oils and often seem to have a more comprehensive aroma.
This method is a highly specialized extraction method. Because the solvent evaporates, the essential oil contains no solvent impurities and the separation is thorough. The extracted molecule may be larger than the distillation class. Here is a case that needs to be explained that the distillation method brings out aromatic molecules through steam, but larger molecules cannot be extracted, such as the diterpene molecule in Clary Sage, which is already the limit, that is 20 Distillation extraction of terpenes of carbon atoms has rarely been seen.
Of course, some people also doubt that carbon dioxide is an acid gas, so this extraction method will destroy the chemical structure of the essential oil more or less.
Although the essential oil extracted from this method will be very similar to the original aromatic composition in the plant, it is a fairly perfect extraction method. However, the equipment used for this extraction method is not only large in quantity but also very expensive. Taking it to extract essential oils often takes several years to balance costs. Until today, the price of essential oil extracted with supercritical carbon dioxide is still very expensive.
Surprisingly, this is not necessarily close to nature. Taking ginger as an example, ginger essential oil extracted with supercritical carbon dioxide naturally outperforms distilled ginger essential oil, but it is also easy to stimulate sensitive skin. In addition to the high price, the essential oil of supercritical carbon dioxide extraction has a drawback, that is, few manufacturers are willing to provide, and it is not easy to buy.