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Here we explore various refinement methods for removal of plant waxes from cannabis extract.
As refinement methods grow in the world of cannabis extracts, here we explore various refinement methods for removal of plant waxes from cannabis extract.
More than 400 chemical compounds have been identified in the cannabis plant (Figure 1). Some of these compounds are targeted during extraction and others, such as waxes, are extracted alongside the targeted compounds. Plant waxes are composed of a variety of compounds, such as fatty acids, hydrocarbons, esters, lactones, and alcohols (1). Most plants, including cannabis, produce waxes that exist on the plant’s surface. The purpose of the plant’s wax layer is to modulate hydration and protect the plant’s exposed surface (2). The cannabis wax layer is easily soluble in many solvents that are used for cannabis extraction, such as supercritical CO2, ethanol, and hydrocarbon extraction. While waxes prove to be useful to plants, they are often an undesirable by-product of extraction methods. Waxes dramatically impact the viscosity as well as the complex chemical profile of cannabis extract.
The viscosity, clarity, and flavor of cannabis extracts are all distinct characteristics of the various concentrate products found in the cannabis marketplace. Currently, the primary wax fractionation process in the industry is called winterization.
Winterization is the process of removing fats and waxes from botanical oils to prevent crystallization of certain compounds in the oil.
Not only does the winterization process reduce the viscosity of an extract, it also increases the concentration of other desirable compounds such as cannabinoids and terpenes. The winterization process involves mixing crude extract with organic solvents like high-proof ethanol over heat to dissolve the extract (Figure 2). Once dissolved, the ethanol–extract solution is frozen to facilitate crystallization of the waxes. Once thoroughly frozen, the solution is processed through vacuum filtration to separate wax solids from the oil–ethanol solution.
As cannabis and hemp operations have begun to scale up, pressure has increased on advancements in winterization and filtration technology. Winterization continues to be a bottleneck in the refinement process. Extraction operators have continuously developed more selective extraction methods to fractionate the wide range of cannabis compounds. These methods are moving closer to selective separation of desirable from undesirable components. However, refinement processes of some fractions are still used to meet quality, consistency, and efficiency standards. For example, “wax fractions” would be winterized to extract any cannabinoids that may still be in the fraction to ensure all cannabinoids are captured in the process. The various desirable fractions would then be mixed together or used separately to create final products.
Ethanol extraction equipment manufacturers have innovated by significantly lowering extraction temperatures as well as sequentially linking extraction and post-processing steps into one unified system. Reducing extraction temperature has increased the extraction efficiency by selectively extracting cannabinoids and leaving behind undesirable compounds such as wax and chlorophyll. Full service processing equipment, which would sequentially complete extraction, winterization, filtration, and solvent evaporation in one piece of equipment, has continued to rise in popularity. This significantly reduces hands-on labor and has amplified efficiency from start to finish.
The aforementioned full service ethanol processing equipment model has not yet been successfully implemented in other extraction methods. However, I believe in the very near future supercritical CO2 extraction equipment manufacturers will have the technical capability to selectively filter wax from the raw CO2 cannabis extract within the supercritical CO2 system itself. This may be implemented via in-line filtration paired with improved selective fractionation capability, but all of this has yet to be seen.
Finally, centrifuge technology has continued to surface as an option for selective separation of waxes from cannabinoid and terpene fractions. Using centrifugal force, heavy waxes are pulled to the bottom of the vessel physically separating the chemical components. However, the cost of a centrifuge large enough for efficient operations is a significant investment. This technology requires massive up-front capital costs with a long return on investment (ROI) time line.
After reviewing the various methods of wax fractionation, it is clear that time, equipment costs, and operating costs play a significant factor in deciding which method to implement in daily operations at cannabis and hemp facilities. Due to the relatively minimal investment in standard vacuum filtration, it continues to be the primary wax fractionation method to date. I am eager to see the technology strive to improve wax fraction purity and overall process efficiency as this industry develops.
Lo Friesen is the founder, CEO, and Chief Extractor of Heylo. With a background in chemistry and clinical research, Lo was inspired to explore cannabis as a medicine and to enter the emerging industry. She joined Eden Labs, a leading CO2 extraction equipment manufacturer to support and expand a Research and Development department. There she managed the development of their latest and greatest CO2 extraction system. In 2017, after working with Eden Labs and another cannabis processor, Lo launched Heylo with a mission to help people get more out of life with cannabis.
L. Friesen, Cannabis Science and Technology 3(9), 12-14 (2020).