There are three ways CBD can be extracted from industrial hemp biomass, though some are more effective than others. The key to determining which method is best lay in determining what the finished product will be used for and the desired level or necessity of purity.
These three methods are Olive Oil Extraction, CO2 Extraction and Ethanol and Solvent Extraction .Decarboxylation is the process of separating natural phytochemicals, terpenes and and cannabinoids from the hemp. Heat must be used in the process in order to release these compounds.
The oldest and simplest of these of course is Olive Oil Extraction is the oldest and simplest method. It is still commonly used for at-home and small-scale operations and is inherently safe as there is no danger of explosion, which is always a positive. While other oils, including coconut and medium-chain triglycerides(MCT) oil, which is derived from coconut and easily absorbed into the body, as well as various nut oils, extra virgin olive oil is preferred as it is more successful at extracting hemp’s beneficial compounds. Further, olive oil has good flavor and provides its own high antioxidant levels.
Ethanol and Solvent Extraction is best used to create high-yield CBD isolate and distillate. It is not recommended in the creation of wax, full-spectrum or essential oil as the extraction process not only damages terpenes and phytochemicals, but trace residue of the solvent (commonly butane) will remain in the product. These quantities must remain under 0.5 percent or the end product will not be sellable. While ethanol is highly purified alcohol and dissipates, trace amounts of butane can remain and is known to impact lung function.
Regardless of whether ethanol or solvent is chosen, the process is the same. Solvent added to the biomass separates the phytochemicals, terpenes and cannabinoids from the hemp. This method does yield higher CBD content per pound of biomass over CO2 extraction and is also less expensive. This method also poses some danger as ethanol and solvents are flammable and combustible.
CO2 Extraction is often the preferred method. In its original gaseous form, when pressurized, CO2 converts to a natural liquid solvent that separates the desired properties from the source plant and leaves no residue as its high diffusion rates penetrates solids faster than liquid solvents.
While C02 Extraction is the primary process category, it is also divided into subcategories supercritical, subcritical and midcritical, which designates the temperatures and pressures required to pull CBD, CBG, flavinoids and terpenes from the plant matter.
CO2 is run through a chamber that increases pressure and reduces the temperature to as much as -70 degrees Fahrenheit (depending on the process), converting it to liquid. As this passes through the chamber holding the plant material, breaking down the trichomes’ membranes and capturing cannabinoids and terpenes.
While one would think supercritical is the best and is often touted by extraction services as such, this can in fact produce lesser results as temperatures can adversely effect the smaller molecule-comprised properties such as terpenes and other heat-sensitive chemicals.
Subcritical extraction uses the lowest temps and pressures, requires more time to process material, produces less yield but is better able to retain important oils and chemicals found in the plant. As the name implies, midcritical falls in the mid-range of super and subcritical, and is a gentler extraction method.
CO2 extraction has benefits for both extraction service companies and the consumer. Since CO2 can be reused, overhead costs are reduced. It is also a clean process, with very low environmental impacts. For consumers, this means no exposure to residual solvents that may be found in products derived from other extraction methods.