As our overview of cannabis drying methods touched on, freeze-dried cannabis is considered one of the best drying options because it preserves the volatile compounds and acidic forms of cannabinoids (Lazarjani et al., 2021). Essentially, freeze-dried cannabis maintains a large amount of the original plant’s terpene and cannabinoid makeup (Al Ubeed et al., 2022). This method transcends cannabis, as it has been used to preserve high-quality foods, pharmaceuticals, and other things since the 1950s (McHugh, 2018). It’s quick, as it can take less than 24 hours (Leafly, 2020), and while it has a high-operating cost, many cultivators are steering towards this drying method.
How Freeze Drying Cannabis Works:
In general, the freeze-drying process happens when the solvent (in this case, cannabis) is kept at a low temperature, where sublimation removes the mositure content (McHugh, 2018). This process has three crucial steps: deep freezing, sublimation, and final drying (Loeffler, 2021).
Deep Freeze: As is in the name, this phase brings cannabis buds to about -40 degrees Fahrenheit (Loeffler, 2021). This phase prevents large ice crystals from forming, which works well because large ice crystals would degrade the final product’s quality (McHugh, 2018).
Sublimation: This is the combination of low pressure and low temperature, which turns solid materials (i.e. ice crystals) into a gas state (i.e. water vapor) (Leafly, 2020). This process “accounts for about 45% of the total energy consumption for the process, while application of vacuum and condensation each represent about 25%” (McHugh, 2018).
Final Dry: This process vaporizes any remaining water molecules, without damaging the proteins and lipids (Al Ubeed et al., 2022), by raising the temperature higher than the primary drying phase (McHugh, 2018).
An Option: A Blast of CO2
Some growers have found that a blast of liquid CO2 helps separate cannabis leaves and other particles from the buds more efficiently than traditional trimming methods (Leafly, 2020). This method doesn’t initially utilize the same low temperatures as traditional freeze-drying (Leafly, 2020). Instead, it uses about the same temperature as one would for serving ice cream, which, as Leafly puts it, “allows the buds to retain their integrity and potency while leaves and other chaff fall into the Resinator’s collection chamber” (2020). This addition to freeze-drying is interesting, as it is still relatively new.
Rely on Steep Hill
Whatever your chosen drying method, Steep Hill is here for all your cannabis testing needs. We are located in Ottawa, Illinois, and are proud to help build Illinois on the backbone of reliable, accurate science. We offer potency and terpene testing and so much more. Contact us today to get started!
References:
Al Ubeed, H. M. S., Wills, R. B. H., & Chandrapala, J. (2022, March 6). Post-harvest operations to generate high-quality medicinal cannabis products: A systemic review. Molecules (Basel, Switzerland). Retrieved January 3, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8911901/
Leafly Staff. (2020, November 17). CO2 trimming and freeze drying: Crop to cure in 24 Hours. Leafly. Retrieved January 3, 2023, from https://www.leafly.com/news/industry/crop-cure-24-hours
Loeffler, B. (2021, July 12). Freeze-drying for cannabis preservation. North Slope Chillers. Retrieved December 29, 2022, from https://northslopechillers.com/blog/freeze-drying-for-cannabis-preservation/
Lazarjani, M. P., Young, O., Kebede, L., & Seyfoddin, A. (2021, July 19). Processing and extraction methods of medicinal cannabis: A narrative review - journal of cannabis research. BioMed Central. Retrieved December 22, 2022, from https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-021-00087-9
McHugh, T. (2018, February 1). Freeze-drying fundamentals. IFT.org. Retrieved December 29, 2022, from https://www.ift.org/news-and-publications/food-technology-magazine/issues/2018/february/columns/processing-freeze-drying-foods