So what is the buzz about CO2 extracts in aromatherapy? Let’s take a look.
What are subcritical CO2 extracts?
The name sounds a bit scientific and technical, but it is not scary and CO2s are very cool. CO2-extraction, aka Supercritical CO2 extraction, is a relatively modern technology for production of lipophilic plant extracts. Lipophilic means the ability of a chemical compound to dissolve in fats, oils, lipids, and some solvents such as hexane or toluene. The word comes from the Greek λίπος meaning “fat” and φίλος meaning “friendly.”)
What is so good about it?
The thing that is great about CO2 extraction is it is extremely gentle and there is absolutely no residue left in the extract (like with absolutes like jasmine absolute), and many more constituents are present than in steamed distilled/hydro- distilled essential oils (many components are lost due to the high heat). One of the best things about these extracts is that they are sterile and need no preservation.
What were CO2 extracts developed for in the first place?
So this method was initially developed for the foods and flavorings industry (e.g. spices, hops, tea, vegetable oils), it now is being used for aromatic extracts in the perfumery and aromatherapy industry. It’s a HUGE HIT!
Great! So how exactly do they make CO2 extracts?
CO2 (Carbon dioxide) gas is pumped into a chamber that is filled with the botanicals that are to be extracted. This is the cool part! The carbon dioxide gas has liquid properties while remaining in its gaseous state. Is that not awesome? This happens because the CO2 is held at or above its critical temperature and critical pressure.
How do we end up with the extract?
The CO2 in its subcritical state acts as a solvent and becomes saturated with aromatic constituents. It is then pumped into a chamber with a different temperature and pressure and voilà – the CO2 reverts back into its normal state, leaving behind the aromatic extract. The CO2 is then recycled.
Anything else that I should know about CO2 extracts?
Actually, yes. There are two types of CO2 extracts: Select and Total
CO2-se (select) extracts have been produced at a lower pressure (80–140 bar). CO2 Select extracts are similar to essential oils but usually are much thicker in viscosity. They are like steam/hydro distilled essential oils in application and composition but they contain way more volatile components than steam distilled extracts.
CO2-to (total) extracts are produced under high pressures (up to 550 bar) and contain all CO2-soluble lipophilic plant constituents, e.g., essential and fatty oils, carotenoids, lipophilic antioxidants, sterols, tocopherols, other bioactive constituents, resinoids and waxes. This makes the extract very similar to the plant itself. CO2 Totals are generally thick and pasty or even solid.
Think of it like this. Essential oils and absolutes are like a cheese pizza.
CO2 Selects are like a cheese pizza with pepperoni. CO2 Totals are like a cheese pizza with all the toppings.
They are both awesome!