As cannabis expands into medical and various recreational products, manufacturers apply a variety of methods to extract the essential components. Cannabinoids make up the key active components, and cannabis contains about 80 of them. The most well-known cannabinoids are cannabidiol (CBD) and tetrahydrocannabinol (THC). THC is the main psychoactive component, and CBD could be useful for a range of medicinal applications. To prepare the various products—from edibles and liquids to smokables and lotions—the crucial chemical components must first be obtained from the plants.
After being harvested, manufacturers can process the material using a number of cannabis extraction methods to create these marijuana concentrates. In many cases, manufacturers opt for solvent extraction or supercritical CO2 extraction. Typically, solvent extraction relies on solutions of water and alcohol, usually ethanol, as it is economical, but this solvent must later be removed. The supercritical CO2 method, which removes the active components with CO2, provides efficient extraction, but the start-up cost is higher and it takes some time to set the parameters of the technique. Several other steps—including concentrating the extraction mixture, separation steps and further concentrating—are usually performed (after extraction) to create the final product.
According to Leo Zhou, Business Development Manager for Chromatography at BUCHI, “Most groups are using solvent extraction—mainly soaking or stirring in ethanol with heat or at room temperature—and a few are using supercritical fluid extraction, SFE.”
In addition to being less expensive, solvent extraction is easy to set up and scale up. Nonetheless, Zhou points out some shortcomings of this technique. For example, he says, that “using a lot of solvent is expensive, but it can be recycled using distillation.” In addition, solvent extraction is not very efficient.
SFE, on the other hand, is very efficient and uses less solvent. Beyond the high start-up costs in equipment, Zhou also points out that it can be complicated to operate.
Scientists have used both techniques for a long time. “Even SFE has been used on natural products for many years,” Zhou says.
Upping the efficiency
Mountain High Suckers in Colorado uses ethanol extraction. Owner Chad Tribble says, “We get close to 200 proof.” This company soaks the cannabis in the alcohol mixture for a specific amount of time, then uses evaporative distillation to remove some alcohol and then performs an extraction that Tribble describes as “basically like a reduction.”
With this process, Tribble’s team typically runs batches of about 10 pounds. “It can be bigger,” he says, “but we make batches often, so we don’t need large size.”
Right now, Mountain High Suckers runs a semi-automatic process, which is about half hands on and half automated. “We can scale up this process based on the needs of the market,” Tribble explains.
Over time, companies fine tune the process. “In the years we’ve done this,” Tribble says, “we’ve become more efficient in run times and developed better flavor profiles.”
Today, most companies use stock instrumentation that was developed for other industries. Nonetheless, Tribble and his colleagues are working with a company, Eberbach, on what he describes as “the world’s first commercial ice-water extraction, where the solvent is water.” The cannabis is aggregated in ice water and then put through a sieve to obtain the product.
In the next few years, a variety of vendors will bring dedicated extraction platforms to the market and advances in methods and existing equipment will continue to drive efficiency and lower running costs. If that happens, the process could become more efficient and controllable than ever.