Humans have cultivated cannabis for millennia, due to its variety of uses for food, textiles, smoking and medicine. With technology advancing, various forms of processing have made cannabis all the more valuable. Recently, Epidiolex an oral solution of plant-derived cannabidiol made news as it was approved by the U.S. Food and Drug Administration for treatment of seizures associated with epilepsy. Epidiolex is produced by extracting cannabidiol, or CBD, from the plant. It is the non-psychoactive counterpart of tetrahydrocannabinol, or THC. These two major components of cannabis are isolated by extraction.
Extraction is the process by which a desired substance is separated from a matrix. In this case, cannabis extracts, or terpenes, are separated from the plant. Cannabis comes in a variety of strains that can be distinguished from one another by the amount of terpenes they contain. In addition, such differences give each cannabis strain its unique scent and aroma.
The most common form of extraction is hydrocarbon extraction. This process involves the use of propane or butane as solvents to strip cannabinoids from the plant. Cannabis oils, shatter, rosin, hash and wax are among the many end products. When properly utilized, hydrocarbon is considered a clean method that leaves no residue. Hydrocarbons are nonpolar compounds made of hydrogen and carbon. Most are manufactured by-products of the petrochemical industry that are derived from natural gas, diesel fuel and gasoline. They are highly flammable but very efficient. All hydrocarbons have potential use in cannabinoid extraction. However, in practice, lower hydrocarbons are used, like propane and butane. These are extremely volatile and flammable, but they evaporate quickly, resulting in efficient recovery of dissolved cannabinoids.
The process of hydrocarbon extraction usually starts with packing cannabis plant material into a glass tube. It must be airtight, and a screen is attached to the bottom to prevent material from falling off. Next, the tube is placed in a glass container. Propane or butane is then introduced on the other end, ignited and allowed into the tube to heat up the plant material. Within minutes, the flower starts releasing oils, which drip out of the tube into another glass container. The container with oil is then placed into another container with hot water, which allows the solvents to evaporate quickly. Further purging is sometimes necessary to remove any leftover hydrocarbon to produce clean oil. Colored pigments and chlorophyll are left behind. The low heat evaporation of solvents such as propane and butane allows the oil being produced to form shatter and bubble hash. Hydrocarbon extraction is a dangerous process and thus requires strict adherence to safety measures. A single spark can result in an accidental explosion due to the substances being highly flammable.
Another form of extraction is non-hydrocarbon extraction, which does not involve solvents. One example of a by-product of this process is traditional hash, which is extracted through a process involving ice and water. A full plant is chopped and frozen and then broken into smaller and smaller parts over a wire screen. To a casual observer, the cannabis bud is just a part of the plant with no other unique feature. If you look more closely, however, fine hair-like growths can be seen all over the bud or flower. These are called “trichomes,” from the Greek word trichoma, meaning “growth of hair.” These hairs contain the oils and terpenes sought from herb.
Trichomes can also be separated via dry sieve. The process is as simple as rubbing leaves and buds through the surface of a fine wire mesh. Upper parts of the flowers and buds are typically selected, since they contain the greatest concentration of terpenes and cannabinoids. Some manufacturers use additional finer wire meshes for a purer result. The powder can be smoked or heated to further produce hash. Some are made into blocks. Rosin, which is a translucent substance with a sap-like consistency, has become popular as well. The extraction involves heat and pressure, which is similarly time-consuming as a solvent-based process. One benefit of this method is the absence of harmful solvents in the resulting product.
Over the years, growers and manufacturers have been developing methods to produce the best-quality cannabis by-products. With the industry growing steadily amidst many challenges, there is no doubt that the business of extraction will soon be another big segment. The demand for cannabis oils and terpenes, especially in the field of medicine, is a sign that thorough research is necessary to enhance technology used in extraction. Two major concerns are the safety and purity of the products available on the market. Manufacturers need to make sure their products have the best concentration, and not compete for the amount of production. At present, we are hopeful that with the growing interest in the legalization of the cannabis industry in many states, safer methods of production will also be developed.