What Are CO2 Cannabis Extracts and How Are They Made?Patrick BennettJanuary 29, 2018
Although fairly new in cannabis concentrate processing, this technology is anything but new to the botanical extraction industry at large. However today, the use of CO2 for cannabis extraction is quickly positioning itself to be one of the leading technologies for industrial hash oil production. While the reason for this paradigm shift is certainly debatable, the technology’s versatility paired with improved sustainability and safety are strong indicators.
At the consumer level, retailers more than ever now are labelling their concentrates by extraction method, detailing whether or not solvents were used and to what extent. One popular dichotomy that exists in the cannabis extraction market is between petroleum-based solvents such as butane or propane and more natural solvents such as CO2.
But what exactly is a CO2 extract and how is it produced?
What Is Supercritical CO2 Extraction?
Supercritical fluid extraction (SFE) is the process of separating components from each other by use of a particular type of solvent. These types of solvents are labelled “supercritical” by virtue of the fact that when they are exposed to extreme temperatures and pressures, they display structures that fluctuate between intermediate states of solid, liquid, and gaseousness.
When in this state, supercritical fluids are capable of breaking down structures where they can then be separated, or fractioned. Among the variety of supercritical solvents used for this process, the most common by far is CO2.
Supercritical (sc-CO2) extraction has been around for decades, appearing first in the 1980s and 90s as a cleaner and more viable alternative to other methods of separation and extraction. From the decaffeination of coffee and tea to the extraction of essential oils for perfumes, this process has become commonplace in many industries.
What Are the Benefits of Using CO2?
Carbon dioxide within our natural atmospheric temperature and pressure rests in a gaseous state. CO2 must be frozen and compressed into a liquid and then further until it reaches its supercritical point. Under controlled circumstances, supercritical CO2 can be used to dissolve substances into “fractions” that can be removed.
There are several reasons why CO2 is particularly useful within botanical extractions, namely with cannabis:
- CO2 is a naturally occurring compound. It exists all around us and our bodies produce it.
- As far as non-polar solvents are concerned, CO2 is among the safest. In fact, the FDA has labelled CO2 safe for industrial extractions, making it a much less controversial solvent than petroleum based hydrocarbons such as butane or propane.
- The conditions that allow CO2 to change from a fluid state to a supercritical state can occur without having to exceed temperatures above 90°F, meaning there is less risk of compromising the natural volatile compounds found in cannabis.
- CO2 is also unique in that its solubility will change with pressure, allowing for fractioning of the many different types of biomolecules available in cannabis strains. CO2 extraction can be used to pull various cannabinoids from the plant such as THCA, CBD, CBG, THCV as well as terpenes and other compounds.
CO2 Extraction Equipment and Process
The equipment and processes used for SFE can vary greatly in cost and complexity depending on scaling requirements. Machines capable of producing and fractioning large quantities of product can cost hundreds of thousands of dollars, and these machines are recommended to be serviced by only highly trained professionals in a lab setting.
The first step in the SFE process is to take gaseous CO2 and run it through a chamber where it will be subjected to extremely low (-70°F) temperatures and enough pressure to cause the gas to change into a fluid. Within this state, CO2 exhibits special properties that when reheated and pressurized become supercritical.
At this state, the supercritical fluid passes through a chamber containing the raw cannabis material. Because of its unique properties, this supercritical fluid can pass through the raw cannabis very easily while gently dissolving the membrane of the trichomes to capture their many active compounds.
The next phase in the sc-CO2 extraction process occurs when the compound-enriched solvent passes into another pressurized separation vessel, only this time the pressures and temperatures will fluctuate in order to fraction the compounds such as cannabinoids and terpenes away.
The separation vessel’s final role in the process is to transport the remaining CO2 to a condenser vessel where the temperature and pressure allow the fluid to stabilize back into a gas. Most industrial scale extractors will actually recycle and reuse CO2, a process which is commonly referred to as “closed loop extraction.”
CO2 Products in the Cannabis Industry
Once a compound has been fractioned using sc-CO2, it can then be further modified and refined depending on the desired outcome. In order to create shelf stable and desirable products for the market, often refinement procedures such as winterization and distillation are incorporated as a secondary process.
Terpene reintegration may also occur where fractioned compounds are reintroduced to a refined THC solution to create a more robust and flavorful experience for those who prefer to vaporize. This process is unnecessary if the final product is intended for culinary uses as terpenes may compromise the integrity of an otherwise odorless and flavorless product that is perfect for a food additive.
What makes sc-CO2 so beneficial for the cannabis concentrate market is the customizability factor. By modifying pressure temperature and solvent ratios, various products can be created ranging from vaporizer-friendly oils to dabbing concentrates such as waxes, crumbles, and even shatters and saps. The range of CO2-based products can be much wider than other extraction methods when used to its fullest potential.
While not always cost-effective, SFE using CO2 has proved to be one of the most versatile and safest methods of producing cannabis concentrates. Today, CO2-based products have saturated almost every major market from consumables to pre-filled vaporizers to dabbing products and isolates. The world of cannabis extraction has benefited greatly from the adoption of this technology, and no doubt, the future of CO2 extraction technology will be positively impacted by its contributions to the cannabis community.