CO2 Distillation Explained
CO2 Distillation Explained
Carbon Dioxide and 'Supercritical' Carbon Dioxide extraction are the latest technologies in distilling essential oils at low temperatures. Both methods involve the use of carbon dioxide as the 'solvent' which carries the essential oil away from the raw plant material. The lower pressure CO2 extraction involves chilling carbon dioxide to between 35 and 55 degrees F, and pumping it through the plant material at 1000 psi. The carbon dioxide in this condition is condensed to a liquid. Supercritical CO2 extraction (SCO2) involves carbon dioxide heated to 87 degrees F and pumped through the plant material at around 8,000 psi – under these conditions, the carbon dioxide is likened to a 'dense fog' or vapor. With release of the pressure, the carbon dioxide escapes in its natural gaseous form, leaving the pure essential oil behind. Supercritical distillation has become the more common of the CO2 methods, though these oils are stilled labeled CO2-distiled or CO2 extracted.
These carbon dioxide methods have a couple of advantages: Like steam distillation, there are no solvent residues left behind, and the resultant product is perfectly pure. Like cold pressing, there is no heat applied to the plant material or essential oil to alter it in any way. The oil produced is very accurate with respect to the original state of the plant. CO2 distillation produces the most therapeutic essential oil for some plants, yet not others. It is highly beneficial for resins such as Frankincense and Myrrh, as more of the larger molecules - considered to have important healing properties - are brought into the essential oil. In fact, it was Frankincense CO2 that was the first of the CO2 oils to be accepted into the practice of aromatherapy by the 'hard core' aromatherapy practitioners when it first arrived on the scene.
Many 'spice' oils seem to have a fuller aroma, with more middle and lower tones when CO2 distilled. Yet the therapeutic values may be different -- while Cinnamon CO2 and steam distilled varities are very similar, Ginger, for example, is quite different depending on the distillation technique. Its benefit to the digestive system is best received from the steam distilled variety, whereas the CO2 oil is best for its anti-inflammatory properties.
It's important to note, there is no 'better' distillation method - each process simply produces a different oil. You'll be hard-pressed to find a CO2 lemongrass, lavender or rose otto. The best thing about the CO2 process is that it has drastically expanded the toolkit of the aromatherapy practitioner.