Curious About CO2's?
Updated: Oct 9, 2020
The use of aromatic plant extracts and essential oils has been embraced by civilizations for thousands of years. Through crude extraction methods, ancient cultures derived aromatic oils from seeds, roots, bark, leaves, wood, flowers and resins and used them in religious ceremony, perfumery, funerary services and many other aspects of life. In the early Orient, Greece and Rome, the oils were obtained by placing plant material into a fatty oil, leaving them to warm in the sun and finally separating the out the aromatic oil. Throughout the early Middle Ages and beyond, a form of distillation was used to prepare floral and aromatic waters.
Today, steam distillation is the most widely used process for extraction on a large scale and is the standard method for producing essential oils. Steam distillations cause sacs in plant material to open up and release their oils, but this process can’t extract heavier compounds, and some constituents can be damaged due to the high heat. Solvent extraction methods produce absolutes, which are different from essential oils because they can contain both aromatic and non-aromatic chemical constituents. The disadvantage is there can be trace amounts of the solvent, typically hexane, heptane or ethanol, in the finished product.
A relatively new and highly efficient process is CO2 extraction. CO2 extracts are oils similar to distilled essential oils and can be tremendously beneficial when used in aromatherapy. The process consists of pumping pressurized carbon dioxide into a chamber filled with plant matter. When carbon dioxide is subjected to pressure, it has liquid properties while remaining in a gaseous state. Because of these liquid properties, the carbon dioxide functions as a solvent, pulling the oils and other substances, such as pigment and resin, from the plant material.
The difference between CO2 extraction and traditional steam distillation is that CO2 is used as a solvent instead of heated water or steam. Let’s compare the differences in the two methods:
Involves temperatures of around 140 to 212 degrees F.
High heat changes molecular composition of the plant.
Temperatures of about 95 to 100 degrees F.
Superior in many cases due to lower heat exposure of plant matter.
Extracts contain more plant constituents.
More full-bodied aroma, closely resembling the herb it is derived from.
As this newer method of extraction becomes established in aromatherapy, more choices are emerging. Here is a look at several commonly CO2 extracted oils and their uses:
Calendula (Calendula officinalis) – Most recognized for its ability to help wound healing, ulcers and abrasions, a CO2 extract contains, not only all the essential oils of the plant, but also the plant waxes and heavier phytochemicals. This extract can be used in healing salves, lotions, creams for chapped, dry or damaged skin. Recommended use 1-5% in formulations.