What are CO2 cannabis extracts and how are they made?

Whether you prefer vapor pens, salves, infused edibles or elixirs, chances are you've tasted a product produced using carbon dioxide (CO2) supercritical fluid extraction technology.

While this technology is fairly new in the processing of cannabis concentrates, it is not new to the plant extraction industry as a whole. Today, however, the use of CO2 for cannabis extraction is quickly positioning itself as one of the leading technologies for industrial cannabis oil production. While the reasons for this paradigm shift are certainly debatable, the versatility of the technology with improved sustainability and safety are strong indicators.

At the consumer level, retailers are now, more than ever, labeling their concentrates by extraction method, detailing whether and to what extent solvents were used. A popular dichotomy that exists in the cannabis extraction market is the difference between petroleum-based solvents such as butane or propane and more natural solvents such as carbon dioxide.


But what exactly is CO2 extraction and how does it come about?
What is supercritical CO2 extraction?

Supercritical fluid extraction (SFE) is a process in which components are separated from each other by using specific types of solvents. These types of solvents are called "supercritical" because when they are exposed to extreme temperatures and pressures, their structure fluctuates between intermediate states of solid, liquid and gas.

When in this state, supercritical fluids are able to break down the structure and then separate or fractionate it. Of the various supercritical solvents used in this process, the most common by far is carbon dioxide.

Supercritical (sc-CO2) extraction has been around for decades, first appearing in the 1980s and 1990s as a cleaner, more viable alternative to other separation and extraction methods. From decaffeination of coffee and tea to extraction of essential oils for perfumes, this process has become very common in many industries.
What are the benefits of using carbon dioxide?

Carbon dioxide is in the gaseous state at natural atmospheric temperature and pressure. Carbon dioxide must be frozen and compressed into a liquid, and then further compressed until it reaches its supercritical point. Under controlled conditions, supercritical carbon dioxide can be used to dissolve substances into "fractions" that can be removed.

Carbon dioxide is particularly useful in plant extraction for several reasons, namely for cannabis.

Carbon dioxide is a naturally occurring compound it's all around us and our bodies produce it.
Carbon dioxide is one of the safest solvents as far as non-polar solvents are concerned. In fact, the U.S. Food and Drug Administration (FDA) has labeled carbon dioxide as a safe solvent for industrial extraction, making it less controversial than petroleum-based hydrocarbons, such as butane or propane.
Conditions that allow carbon dioxide to change from a fluid state to a supercritical state can occur without exceeding temperatures above 90 degrees Fahrenheit, meaning there is less risk of damaging the naturally occurring volatile compounds in cannabis.
CO2 is unique in that its solubility varies with pressure, allowing for the fractionation of many different types of biomolecules found in cannabis strains.CO2 extraction can be used to extract various cannabinoids from the plant, such as THCA, CBD, CBG, THCV, as well as terpenes and other compounds.

The next stage of the sc-CO2 extraction process occurs when the compound-rich solvent enters another pressurized separation vessel, only this time the pressure and temperature fluctuate in order to fractionate off compounds such as cannabinoids and terpenoids.

The final role of the separation vessel in this process is to deliver the remaining CO2 to a condenser vessel where the temperature and pressure stabilize the liquid and turn it back into a gas. Most industrial-scale extractors will actually recover and reuse the CO2, a process often referred to as "closed-loop extraction".
CO2 products in the cannabis industry

Once a compound has been fractionated using sc-CO2, it can be further modified and refined based on the desired results. Refining procedures such as winterization and distillation are often used as a second process in order to create a shelf stable and desirable product for the market.
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Reintegration of terpenes may also occur, where the fractionated compounds are reintroduced into a refined THC solution in order to create a more intense and flavorful experience for those who prefer distillation. This process is not necessary if the end product is for culinary use, as terpenes may compromise the integrity of the odorless and tasteless product, which is the perfect food additive.