CBD products are created from pure, CBD-rich cannabidiol oil that is extracted from the cannabis or hemp plant. Once extracted, it is purified and added to different CBD products such as tinctures, gummies, capsules, and vaporizers. There are many ways to extract CBD oil, including:
As the market for CBD products grow into a multi-billion dollar industry, consumers are increasingly interested in the underlying extraction process and understanding which method is the safest and most effective.
CO2 extraction, also called Supercritical Fluid Extraction (SFE), occurs using a series of chambers and pumps and exposing CO2 to extremely low temperatures and high pressure. This same process is used to decaffeinate coffee and tea and extract essential oils for perfumes.
The first chamber contains pressurized CO2, which is pumped into a second pressurized chamber containing the cannabis or hemp plant. The “supercritical” phase occurs when CO2 is kept between a liquid and gas state so that it breaks down plant material and separates the CBD oil. The CO2 and oil mixture is then pumped into a third pressurized chamber where the gas rises, leaving CBD extract behind.
While this method requires expensive equipment and knowledge of chemical processes, research in the Journal of Supercritical Fluids found that CO2 extraction can yield high CBD concentrations at a 92 percent efficiency.
It is also very versatile. Leafly writes that by controlling the solvent and pressure ratios, CO2 extraction can create a range of concentrates that are customizable for specific CBD products, including vaporizer-friendly oils, CBD concentrates, and topical creams.
Steam distillation uses heat to separate CBD oil from the plant material. As the steam rises through the cannabis or hemp plant, it releases oil vapors that are collected in a mixture of water and essential oil, which is then distilled to extract pure CBD oil.
Steam distillation can be inefficient, however, and requires a lot of plant material. It is also less controlled. At certain temperatures and exposure levels, the steam can damage some of the oil extracts and change the chemical properties of the cannabinoids.
This method uses liquid solvents such naptha, petroleum, butane, or propane to strip cannabinoids from the plant matter, creating a mixture of solvents and cannabinoids. The solvent is then evaporated, leaving CBD extract.
Hydrocarbon solvents are relatively inexpensive and very efficient. The Cannabis Business Executive writes that petroleum solvents such as n-butane are one of the most common extraction methods, noting that the corn and canola oil industry has used this method for decades.
However, there are concerns regarding the potential harmful effects of solvent residue. Research published in the International Association for Cannabinoid Medicines Journal writes that hexane and benzene may be neurotoxic, and naptha and petroleum ether are considered “potential cancer hazards according to their respective Material Safety Data Sheets (MSDS) provided by manufacturers.” Additionally, studies have shown that the evaporation process does not always eliminate trace residuals. Chemical analysis of CBD oil extracted using naptha found solvent residue in the CBD oil despite following the evaporation steps.
Solvents such as oil, butter, extra virgin olive oil, and ethanol can be used to extract CBD oil much in the same way as hydrocarbon solvents. Research in the International Association for Cannabinoid Medicines Journal found that olive oil and ethanol extracted cannabinoids at a high efficiency while avoiding harmful residue.
However, the study found that ethanol also extracted chlorophyll from the cannabis plant, giving the oil extract an unpleasant taste. Additional research has shown that oil solvents cannot evaporate, leaving the CBD extract less concentrated than other extraction methods. Food grade solvents are also perishable, requiring more stringent storage and consumption guidelines.
Each CBD extraction method has its associated pros and cons, and, in the absence of federal guidelines, much of the quality control falls to third party testing and state regulatory agencies. For example, the PhytoScience Institute prepared a series of recommends for the Vermont Legislature regarding CBD extraction, testing, and labeling. The Institute recommends that any CBD product, regardless of extraction method, be tested for:
The Institute also recommends the following acceptable limits for hydrocarbon residual solvents. The lower the acceptable limits per gram, the more toxic the substance.
|Substance||Acceptable Limits per Gram (in PPM)|
|Total Xylenes (m, p, o-xylenes)||<1|
|Any solvent not permitted for use||0|
Source: PhytoScience Institute
There is no single “best method” for extracting CBD oil. Hydrocarbon solvents pose greater health risks due to the possibility of residual contaminants, but they are very efficient. While CO2 extraction does not use solvents, it is one of the more expensive extraction methods. Ethanol is efficient and inexpensive, but the flavor profiles are not always pleasing.
According to Hazekamp Herbal Consulting, the global nature of CBD production, where raw materials are “cultivated in one country, while extraction takes place in another, lab testing in a third, and sales take place in yet another country,” reinforces the need for “thorough analytical testing of final products by certified third-party labs.”
The safest and most effective extraction method is the one that is completed by a reputable chemist in an accredited laboratory that follows criteria set by the International Organization for Standardization (ISO) 17025. CBD products should also include the measurement of potency and the levels of contaminants at a 95 percent confidence level.
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