In a previous blog, we discussed the methods and the benefits of plant extracts derived via CO2 extraction. This relatively new process offers an extract product that’s even broader in its aromatic profile and contains even more therapeutic compounds than extracts derived in other ways. Basically, CO2 essential-oil extraction seems like an all-around win–win. It’s a fantastic method for creating extracts useful in myriad contexts. We’re going to take another quick look at the CO2 extraction process before we turn, in this blog, to considering several questions:
- What advantages do these extracts offer?
- Which practitioners and industries use CO2 extracts? Why?
- Are there any drawbacks to CO2 extraction?
CO2 Extraction: A Quick Review
Recapping briefly, CO2 extraction takes advantage of the fact that, when pressurized, CO2 becomes a liquid. This liquid can be used as a solvent that pulls the aromatic compounds, as well as other compounds intrinsic to a plant, from the plant material and into the solvent. Once the CO2 is depressurized, it returns to gaseous form and evaporates out of the extracted liquid, leaving only the plant essences behind.
Two types of CO2 extract can be derived using this process, depending on the pressure used to disperse the CO2 through the plant material. A CO2 Select extract utilizes lower pressure to liquify the CO2, yielding a product that contains only the volatile aromatic compounds of the plant material (it will contain a broader array of aromatic compounds than essential oils derived via steam, since some aromatic molecules extracted by CO2 are too heavy to be pulled out by steam). A CO2 Total extract is the result of more highly pressurized CO2 passing through the plant. The resulting essential compound is thicker and may possess an even broader array of aromatic compounds than either a steam-extracted or a CO2 Select product. A CO2 Total extract may also contain lipids, waxes, and other soluble particles.
CO2 Extraction’s Benefits
CO2 extraction offers the benefits of purity and molecular stability. In contrast to other essential-oil extraction processes, CO2 extraction requires no chemical solvents, such as hexane. The CO2 itself is totally inert—meaning that the final product contains no residual traces of solvent chemicals that might hinder or negate an extract’s therapeutic benefits or scent profile. Plus, CO2 extraction doesn’t require that high heat be applied to the plant material, as is the case with steam distillation. The resulting extract therefore boasts the same molecular profile present in the original plant substance—no heat has affected the molecular (and therefore the scent or chemical) structure in the plant matter.
Who Uses CO2 Extracts, and Why?
So, given how molecularly intact and pure CO2 extracts are, who’s taking advantage of their unique properties? Essentially, any industry, healing profession, or craft that stands to benefit from an extract’s expanded aromatic or molecular profile.
The cannabis (i.e., marijuana) industry—which manufactures cannabis products for medical and recreational edible, inhalation, and extract use—is singing the praises of CO2 extraction, because the cannabis oil extract that results is extremely intact in both flavor and psychoactive effect. Delicate compounds like cannabinoids and terpenes remain whole because of the moderate temperature required for extraction, and no toxic petroleum-based solvent traces are left in the cannabis extract, as they would be if hexane or butane were used. Given the compromised immune systems of many of the persons using cannabis for medical purposes, purity is crucial.
Chefs and bakers can take advantage of the subtle yet potent flavor and aromatic profile of CO2 extracts. Because CO2 total and select extracts quite literally contain more of the parent plant, they offer layers of flavor and scent that can be dramatically more intense, deeper, and even qualitatively different from the flavor profile of steam-distilled oils. Some examples of excellent CO2 extracts for cooking are cardamom, basil, and cinnamon. You may want to try adding a drop or two of a chosen nontoxic CO2 extract to your next batch of spice cookies or pumpkin bread—give it a try and see what you think! N.B.: A little goes a long way—and always, always check to ensure that the extract you’re using is safe for internal use!
Aromatherapists and holistic healers in many traditions benefit from the more complete aromatic and plant-substance content of CO2 extracts. As we noted in our previous blogs, many CO2 extracts will have different colors, scents, and even subtly unique therapeutic properties relative to steam- or chemical-distilled essential oils. Some practitioners will prefer the CO2 extract form to the steam-distilled form of a plant for certain applications, and vice versa.
CO2 extracts are coming into their own in the perfume industry, as well—once, again, they are favored for their nuanced, deep aromatic profiles and the integrity of their molecular structures, which can be important in layering scent components.
Drawbacks and Caveats: A Potential Pitfall of CO2 Extraction
The biggest potential risk of CO2 extraction lies precisely in its thoroughness.
The CO2 extraction method very effectively concentrates the good stuff from source plant material—its aromatic particles, lipids, and waxes all are extracted undamaged in varying proportions, depending on whether a total or select extract is created.
CO2 extraction, however, also very effectively concentrates negative substances. That means that a CO2 extract is really, truly only as good as its source substance: CO2 extraction can concentrate pesticide residues present in source plant material by 700 to 5,300% (7 to 53 times). So be sure, please, that any CO2 extract you use is created from 100% organic, unsprayed plant source material.
There you have it—a brief rundown on pretty much the newest way to extract plant essence in its most complete form. Organically sourced CO2 extracts are becoming more and more available on the market, so give them a try. Enjoy!
 Guba, R. (2002). “The Modern Alchemy of Carbon Dioxide Extraction.” International Journal of Aromatherapy 12 (3), 120–126.