Several common forms of cannabis extraction rely on a solvent, such as alcohol. The technique is relatively simple – cannabis soaks in alcohol, usually ethanol, the plant material is then removed, the liquid filtered, and the alcohol removed with some form of evaporation. One of the biggest challenges is the inherent polarity of solvents like ethanol—meaning it has a propensity to mix with water and dissolve water-soluble molecules like chlorophyll. Removing the chlorophyll from the extract is important as it produces an undesirable, bitter flavor.
This method can be performed at atmospheric pressure, but the temperature is carefully controlled, especially during evaporation. This process can also take time and must be done carefully to avoid danger as ethanol is highly inflammable. One of the biggest benefits of this form of extraction is that there is no risk of leaving toxic residual chemicals in the final cannabis extract and, it enables the co-extraction of all compounds of interest, chiefly cannabinoids and terpenoids.
Ethanol Extraction References