Many methods are used to extract various compounds from botanicals. Choosing the right extraction method for a given ingredient or product requires consideration of the characteristics of each available method. The most popular involve the use of solvents to diffuse the plant material and draw out plant compounds. The solvent is then removed from the final extract. The most common solvents are water and alcohol, but there are some limitations on the types of compounds they can extract, depending on temperature and other factors. More toxic organic chemicals are also used and can draw out certain compounds that elude water and alcohol, but these harsh chemicals can leave residues that are challenging to remove or minimize. Gentler methods such as steam distillation are limited in the types of compounds they can extract, but the growth of supercritical extraction offers solvent-free alternative that can pull out a full range of compounds from raw plant materials.
Deciding on the best extraction method for a given product involves many considerations, the first of which is the desired specifications for the final extract. This includes not just the types and concentrations of plant compounds, but it also depends on the desired marketing (e.g. “solvent-free"), target market (local regulations, such as California’s Propostition 65) and, as always, costs. Knowing the pros and cons of the various available extraction methods and utilizing key resources (e.g. USP, AHPA, ABC, etc.) will help narrow down the decision. In the end, the best ally may be the extraction partner, as any high-quality extract supplier should have extensive extraction knowledge and expertise.