The practice of cannabis drying has existed for as long as cannabis itself. The University of Sydney reports that cannabis usage can be traced back to 2800 BCE when it first appeared in Emperor Shen Nung’s pharmacopeia (n.d.). From there, we have found many ways to grow, cultivate, distribute, and consume cannabis. For drying specifically, there are many approaches to dry out the cannabis plant. The Industrial Crops and Products journal published Chang Chen et al.’s 2021 study discussing various cannabis drying methods and conditions. They found that:
“As the drying temperature increased from ambient to 90 degrees Celsius, drying time reduced from 1800 to 210min, cannabidiolic-acid conversion increased from 0.2%-14.1%, and total terpene retention decreased from 82.1%-29.9%. The total cannabidiol retention (ranging from 83.8%-98.6%) was affected by the drying methods and conditions" (Chen et al., 2021).
Essentially, drying cannabis is a vital part of cultivation. So, without further ado, here is everything you need to know about these four popular ways to dry cannabis.
Hot Air Drying / Hang Drying
This is one of the earliest drying methods (Al Ubeed et al., 2022). Typically, people using this method will remove the extra stems from cannabis plants and then place them to dry on racks or hang them on string lines, wire cages, or static wires (Al Ubeed et al., 2022). Hot air drying/hang drying can take up to 14 days to get the desired moisture levels, requires daily inspection and proper maintenance, and has a potential for mold growth because of its uncontrolled conditions (Al Ubeed et al., 2022).
Oven Drying
Oven drying is far faster than hot air/hang drying – it can happen in vacuum chambers, vacuum desiccators, or a drying oven (Al Ubeed et al., 2022). The oven temperature is vital, as a temperature past 37 degrees Celcius will cause acid buildup and decrease the total yield of cannabinoids in a bud (Al Ubeed et al., 2022). Even in perfect circumstances, oven drying can yield lower THC and CBD content while yielding higher CBN levels (Lazarjani et al., 2021).
Microwave-Assisted Hot Air Drying
Microwave-assisted cannabis drying uses microwaves and continuous flow methods to create dry buds (Radoiu et al., 2020). This type of drying functions between “the radio and infrared wavelengths on the electromagnetic spectrum… [And] is based on volumetric heating and creating a temperature gradient” (Al Ubeed et al., 2022). Compared to other methods, it processes higher volumes of cannabis in less time, has better efficiency, and produces more consistent and higher-quality cannabis (Radoiu et al., 2020). It also preserves cannabinoids and terpenes (Al Ubeed et al., 2022). However, because such high heat is used, it can cause an off taste (Al Ubeed et al., 2022).
Freeze-Drying
This method keeps cannabis plants at low temperatures to remove vaporized water content through a vacuum chamber (Lazarjani et al., 2021). This is typically done in two steps: the first step reduces the buds to approximately -40 degrees Celsius to prevent water foam formation, and the second removes leftover moisture in the bud without damaging lipids and proteins (Al Ubeed et al., 2022).
In general, Lazarjani et al. say that freeze drying is considered better than most other drying methods because it preserves the volatile compounds and acidic forms of cannabinoids (2021). This “inhibits microbial enzymatic activities, preserves the end product quality,” and maintains the aroma and flavor (Al Ubeed et al., 2022). However, freeze-drying cannabis does require costly machinery and high energy outputs (Lazarjani et al., 2021).
Trust in Steep Hill Illinois
Whatever drying method you use, you can always rely on Steep Hill Illinois to give you accurate, reliable results on everything we test. We are proud to be a part of a network of Steep Hill labs that have consistently used the backbone of science to help build a safe cannabis community. Email us today at info@steephillil.com 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 December 15, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8911901/#B77-molecules-27-01719
Chen, C., Wongso, I., Putnam, D., Khir, R., & Pan, Z. (2021, September 16). Effect of hot air and infrared drying on the retention of cannabidiol and terpenes in industrial hemp (cannabis sativa L.). Industrial Crops and Products. Retrieved December 15, 2022, from https://www.sciencedirect.com/science/article/abs/pii/S0926669021008165
History of cannabis. The University of Sydney. (n.d.). Retrieved December 15, 2022, from https://www.sydney.edu.au/lambert/medicinal-cannabis/history-of-cannabis.html
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
Radoiu, M., Kaur, H., Bakowska-Barczak, A., & Splinter, S. (2020, August 21). Microwave-assisted industrial scale cannabis extraction. MDPI. Retrieved December 19, 2022, from https://www.mdpi.com/2227-7080/8/3/45