CBD can be sourced from all cannabis plants but the regulations that came into effect after the US Farm Bill, 2018 require hemp to be used as the source of CBD products sold in the market. Although marijuana-derived CBD products are also available, their sale and possession are handled in an entirely different way and are subject to the marijuana laws of the state.
In this article, we explore various methods of extracting CBD from hemp plants.
Supercritical CO2 Extraction
Reputed CBD manufacturers often use supercritical CO2 extraction, because of the high purity levels it offers. In the method, carbon dioxide is converted to its supercritical state by subjecting it to high pressure under low temperatures.
The compounds from hemp plant matter are extracted by passing supercritical CO2 through it. The method has up to 90% extraction efficiency.
The extraction method is based on an alcohol solvent, mostly ethanol. Ethanol has various applications in the food industry as a preservative and additive.
Being a polar solvent, ethanol mixes with water and dissolves water-soluble molecules in the hemp extract. As ethanol co-extracts chlorophyll with cannabis compounds, the crude cannabinoid-filled oil appears dark and has a greasy flavor.
Chlorophyll is undesirable in the final cannabinoid product and hence it is removed in the post-extraction filtering processes. However, some beneficial cannabinoids may be lost in the process.
The extraction method is based on light hydrocarbon solvents like butane, pentane, hexane, acetone, or isopropyl alcohol. All of them have low boiling points and can be easily used for extracting CBD oil from hemp.
The low associated cost of hydrocarbon extraction is an advantage but hydrocarbon extraction has several associated issues as well and this method of extraction is not much preferred. The oil extracted using this method mostly has a high concentration of THC while the percentages of CBD, terpenes and other cannabinoids are low.
The solvents used for hydrocarbon extraction are toxic and can affect the health of the users even if traces of solvent are left behind in the final hemp product. The residue, on entering the user’s system affects his/her immune function.
The purity of the extraction method has a lot to do with the quality of the final cannabinoid product. When it comes to purity, supercritical CO2 extraction is highly desirable but its high associated cost is a limiting factor. Ethanol extraction also promises appreciable extraction efficiency and purity and it isn’t as expensive as CO2 extraction.