What are the different types of cannabis extraction?
As cannabis extracts fuel the growth of the cannabis market, we’re looking into the history and evolution of extraction methods. You can check out part 1 of our series focused on the origins of cannabis extracts here.
Precision by Agrify is pushing the evolution of cannabis extraction technologies through innovations in efficiency, throughput, and refinement. But how did these extraction methods develop? In part two of our four-part blog series, we’ll detail hydrocarbon and alcohol extraction methods today.
Cannabis Extraction Today
While no official moment delineates cannabis extraction’s past from its present, most in the industry suggest 2010 as the point when clandestine methods faded into the background and a more scientific approach took over. As large recreational markets came online, like Colorado in 2014, there was substantial investment in true extraction laboratories. Companies began to manufacture extraction equipment tailored to their needs and bring in skilled professionals with experience working in the chemical, pharmaceutical, and botanical extraction industries.
As a result, today’s extraction technologies are safer, more efficient, and more scalable than the open blasting or original bubble hash production developed only a few decades ago. With this new technology, operators can now produce a much wider variety of extracts than ever before. Today, the four main cannabis extraction methods are:1https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8290527/
- Hydrocarbon Extraction
- Alcohol Extraction
- CO2 Extraction
- Solventless Separation
In this post, we’ll focus on hydrocarbon and alcohol extraction methods with attention to the pros and cons of each.
Due to the volatile nature of hydrocarbons, hydrocarbon extraction is now performed in entirely closed-loop systems to solve the safety concerns of open blasting. These systems recapture and recirculate the hydrocarbon solvents used in the extraction process so that they are never released into the surrounding environment. While many technical iterations of the closed-loop hydrocarbon system exist, they all operate following the same basic principles.
All steps happen within the same closed, stainless-steel system whose construction and materials have gone through proper state and federal certifications. The system is houses in a C1D1-certified, “explosion proof” room or booth. These changes have transformed this formerly clandestine solvent extraction method into a regulated, well-controlled, and safe process.
The most commonly used hydrocarbons in the cannabis sector are butane (n-butane C4H10), propane (2-methylpropane C4H10), isobutane (2-Methylpropane 75-28-5 Propane, C4H10), or a combination of the three. Newer solvents include hexane and benzene, but these have yet to see widespread adoption. Hydrocarbon solvent extraction begins by slowly soaking the biomass (flower or secondary materials like leaves and trim) in the hydrocarbon solvent in a step called the wash. The hydrocarbon dissolves the trichomes, and the liquid is then discharged through a filtration system to separate it from the used biomass. Depending on the system, the solution may go through a secondary stage (dewaxing or winterization) to remove unwanted waxes and lipids. Finally, the solvent solution goes through the purge, which separates the desirable compounds from the propane and/or butane. The system brings the liquid mixture up to the hydrocarbon evaporation point so the hydrocarbon vaporizes. This vapor then travels into a collection tank to get condensed and recollected. With the hydrocarbon solvent removed from the remaining product, the closed-loop system ends and only pure cannabinoids and/or terpenes remain.
Due to the polarity of the molecules used, hydrocarbon extraction has the best cannabinoid and terpene retention. By manipulating temperature, pressure, and the unique molecular properties of both the solvent and the desired end extraction, producers can create a vast array of products. A few of the most common hydrocarbon extracts include shatter, badder, diamonds, and terpene sauce, with additional products possible through post-processing (distillation).
Hydrocarbon extraction has also led to the development of an entirely new category of cannabis extracts: live products or extracts from fresh-frozen cannabis flower instead of the traditional cured and dried flower. Live resin has become highly valuable as a consumer product because the process captures the strain’s biochemical profile at the peak of potency.2https://hightimes.com/grow/its-alive-the-origins-of-live-resin/
The drawback of hydrocarbon extraction is the high upfront investment required for facility infrastructure, including explosion-proof C1D1 rooms or booths, certifications, and the equipment itself.3https://mjbizmagazine.com/digital-issues/2018-10-Oct/56/ However, the array of possible SKUs hydrocarbon extraction can produce, paired with increased safety measures, are sure to maintain its place at the core of the cannabis extracts market.
Alcohol extraction is a relatively low-cost method that allows for incredibly high throughput potential. If you want to process an entire field of hemp as quickly as possible, look no further! The most common high-grade alcohol used is ethanol (ethyl alcohol, C2H6O), a colorless, flammable solvent with low toxicity.
The first step in the alcohol extraction process is to soak the plant material in the alcohol solvent to dissolve cannabinoids and terpenes. Next, the vessel will agitate or wash the mixture to encourage dissolution. Finally, this mixture, called mistella, gets discharged through a filtration system to remove any undesirable leftover plant matter.
There are two possible approaches to alcohol extraction: warm or cold. Warm extraction leads to a full-spectrum final product as it dissolves lipids, waxes, and other plant matter alongside the cannabinoids and terpenes. Cold extraction freezes these compounds, which are then more easily filtered out for a pure distillation. Warm extraction is relatively less complicated than cold, but the final product requires significantly more post-processing to reach a sellable product.
Whether a warm or cold initial extraction, the final step in alcohol extraction is separating the crude oil from the solvent. The mistella is pumped from the extractor, putting it through a spin dry cycle (typically in a large centrifuge) and then the solvent mixture goes through a recovery process to remove any remaining alcohol. Alcohol used in this process can be recaptured, mixed with fresh alcohol, and used again.
Of all the available extraction approaches used today, alcohol extraction has the highest throughput, as the technology can operate continuously, unlike hydrocarbon extraction, which works on a batch-by-batch basis. As such, alcohol is an industrial-sized approach to cannabis extraction. Like hydrocarbon systems, an explosion-proof room/booth is required in most jurisdictions due to the flammable nature of alcohol solvents.
While alcohol extraction has a high throughput and is one of the most scalable extraction technologies on the market today, it can only produce a limited number of SKUs. This is partially because alcohol extracts and retains terpenes poorly, yielding cannabis distillate as the primary output. This distillate can then be formulated into a variety of different SKUs and forms the base of vaporizer cartridges, edibles, and topicals found across cannabis markets today. Alcohol extraction is also the predominant extraction method used to extract and isolate CBD and other non-psychoactive cannabinoids from hemp. For these reasons, alcohol remains a very popular method of extraction in the modern cannabis marketplace.
Hydrocarbon and alcohol are not the only cannabis extraction methods. If you’re curious about CO2 & solventless extraction, stay tuned for part three in this series to learn more about the options available in cannabis extraction today!