What are CO2 Supercritical Extracts?
CO2 Supercritical Extracts are also referred to as CO2 Extracts and sometimes simply as CO2s.
CO2 Extracts are produced by using a method known as supercritical carbon dioxide extraction.
In its normal state, carbon dioxide is a gas that we breathe continually.
Using specialized CO2 supercritical extraction equipment, however, carbon dioxide can be pressurized until it achieves a fascinating state where it's simultaneously a liquid and a gas. This is known as its supercritical state. Carbon dioxide that has reached the supercritical state is able to act as a solvent that can dissolve the natural components present in the botanical material that is exposed to the supercritical CO2 inside the specialized equipment used for this purpose.
Afterwards, the CO2 is brought back to natural pressurization, and the CO2 returns to its normal gaseous state. What remains is the resulting natural CO2 Extract.
How do CO2 Supercritical Extracts Compare With Absolutes?
Absolutes are typically solvent extracted using hexane as the solvent. Trace amounts of the hexane may remain in the final absolute. However, with CO2 supercritical extraction, CO2 is used as the solvent, and all of the CO2 returns to its normal gaseous state after the extraction is completed. CO2 supercritical extraction eliminates the risk of trace amounts of chemical solvents remaining in the finished extract.
How do CO2 Supercritical Extracts Compare With Essential Oils?
The production of essential oils requires heat in order to distill the plant material. Even for cold pressed citrus oils, some heat can be involved due to the friction involved. CO2 Extracts possess an advantage over essential oils because the botanical material and CO2 supercritical extraction process requires much less heat.
Can CO2 Supercritical Extraction Be Used to Produce Carrier Oils and Other Products?
CO2 supercritical extraction isn't limited to just the production of aromatic extracts. CO2 extraction can also be used to produce superior lipids (carrier oils) that contain more of the beneficial unsaponifiable materials of the plant that cold pressing isn't able to extract.
Even though cold pressed carrier oils are supposed to be pressed at very low temperatures, the friction that occurs can still generate heat during the process. Additionally, not all producers genuinely take the temperature during carrier oil production and still claim the carrier is "cold pressed."
CO2 Extracts are becoming increasingly available through retailers and wholesalers that supply essential oils. Like with essential oils, CO2 Extracts are typically sold in glass bottles. However, some CO2 Extracts are very thick and are sometimes instead sold in small jars. For information on working with thick essential oils and CO2 Extracts, see Using and Blending Thick Aromatic Oils.
What is the Difference Between CO2 Select Extracts and CO2 Total Extracts?
When you shop for CO2 Supercritical Extracts, you should come across extracts that are described as being either a CO2 Select Extract or a CO2 Total Extract. The difference between Select and Total CO2 Supercritical Extracts can be important.
CO2 Select Extracts
To create a CO2 Select Extract, low pressure is used during the extraction process. CO2 Select Extracts generally contain the volatile (aromatic) components of the botanical that are soluble in liquefied CO2. Aromatic molecules each have their own molecular weight. Some aromatic molecules are too heavy to be present in a steam distilled essential oil. However, some of the heavier aromatic molecules are present in CO2 Select Extracts. Therefore, CO2 Select Extracts often smell closer to the aroma of the natural herb than do some steam distilled essential oils.
CO2 Total Extracts
To create a CO2 Total Extract, much greater pressure is used. CO2 Total Extracts contain all (or most all) of the molecules that are soluble in supercritical CO2. CO2 Total Extracts tend to be much thicker than CO2 Select Extracts as they typically contain both the volatile aromatic CO2 soluble constituents, and they also contain the natural lipids, waxes, and other CO2 soluble molecules present in the botanical. For information on working with thick essential oils and CO2 Extracts, see Using and Blending Thick Aromatic Oils.
CO2 Supercritical Extract Book Recommendation
For much more information and to view profiles for over 50 CO2 Supercritical Extracts, I recommend the book CO2 Extracts in Aromatherapy written by Madeleine Kerkhof. Madeleine has been working professionally with CO2 Extracts for over a decade and has a very strong clinical aromatherapy background.