CBD is the therapeutic compound extracted from cannabis plants that has been making quite a buzz in the world markets. Its growing demand and popularity has led to the expansion of the range of CBD products, thereby offering convenient intake methods according to the preferences of the users.
Although cannabidiol is present in the plants, marijuana and hemp that belong to the cannabis species, the differing THC content in the plants led to the legalization of hemp derived CBD while marijuana derived CBD remains as a federal controlled substance in the US.
CBD is extracted from hemp plants using advanced extraction methods like CO2 extraction, ethanol extraction etc. CO2 extraction uses supercritical CO2 as the extracting agent while ethanol extraction uses isopropyl alcohol.
Extraction Methods Of CBD
Hemp plant contains multiple cannabinoids, terpenes, fats etc and the appropriate methods have to be employed to extract the beneficial compounds from the plant.
Supercritical CO2 extraction
CO2 extraction uses supercritical CO2 that is in a state between gas and liquid. The method offers high purity level even though the equipments are expensive when compared to that of other extraction methods. Supercritical CO2 extraction uses high temperature and pressure unlike the two other forms of CBD extraction, sub-critical and mid-critical extraction.
After CO2 in the solid or gaseous state is converted to liquid state, it has to be subjected to low temperature and high pressure to convert it to supercritical state that has properties midway between gas and liquid.
Industrial extraction of hemp CBD takes place inside closed-loop extractor that has three chambers. The first chamber holds pressurized dry ice (solid CO2); second chamber holds dried plant material.
In the initial step, CO2 is pumped from the fist chamber to the second and during the movement, CO2 is converted into supercritical state, which is then run through the plant material to extract the cannabinoids. The extract is finally pumped into the third chamber, where CO2 rises to the top. The final extract that is free of CO2 settles at the chamber bottom.
Solvent extraction uses solvents like butane, propane, ethanol etc to extract cannabinoids and other essential plant compounds from hemp. Solvent extraction is one of the cheapest extraction methods that guarantee appreciable purity levels but the highly inflammable nature of the solvents makes the process quite dangerous.
Along with the cannabinoids, solvent extraction process extracts chlorophyll too from the hemp plant, contributing the bitter taste of the extract. In the beginning of the extraction process, plant trimmings are put into a container after which the solvent is run through the plant material. The process strips off all the cannabinoids from the plant material and the final evaporation process removes the solvent and leaves behind concentrated hemp extract.
If the evaporation step fails to eliminate the solvents from the extract completely, it may contribute to the toxicity of the extract because solvents like butane and propane are toxic. Among the solvents used for extraction, ethanol is the best as it is non-toxic unlike the other solvents.
Purification Methods Of CBD
After CBD oil is extracted, it has to be distilled to isolate individual beneficial compounds.
Here are the steps involved in the isolation of individual from the hemp extract.
The intense nature of supercritical extraction pulls out all compounds from the hemp plant including materials that you do not require in the final product. The process of winterization removes undesirable elements like waxes, fats and lipids extracted from the plant. CBD oil extracted using CO2 extraction is crude oil that requires refining.
In the process of winterization, the extracted oil is mixed with 200 proof alcohol through vigorous stirring and kept in the freezer overnight. The mixture will have a cloudy look in the morning and the fats in the mixture are filtered out by passing it through a filter paper. After the undesirable elements are removed, the alcohol added for winterization too has to be removed using heat.
As the extract is heated to the boiling point of alcohol, it is devoid of alcohol content. The alcohol removed from the mixture can be used in the winterization of another batch of crude oil.
Short Path Distillation
The oil produced after the winterization step is further refined using short path distillation. The process is similar to winterization where the extract is heated to different temperatures to individually obtain the necessary compounds that have significantly different boiling points.
Not all compounds in the hemp plant would be required in the final CBD product because some doesn’t contribute to the overall therapeutic effect of the product while some can even dampen the product quality. Hence their removal is important to ensure that the potency level is maintained.