When you peel an orange, you release its amazing scent—that juicy freshness. The peel keeps all the good stuff inside the orange. The fruit’s terpenes—its essential oils—are fully released when you peel the orange.
This is how it should be with cannabis flower. Her smell should only be released from a protected “shield” of humidity when you grind her. After drying and curing, terpenes need a humidity shield to protect the “good stuff” we expect from our flower. The shield should protect the terpenes and keep them inside, so you smell nothing until grinding. But that is not what happens with most flower.
Back to that peeled orange. Instead of consuming it immediately, let’s say you leave that orange out in the open. What happens? It quickly dries out. And a dried out orange, isn’t as enjoyable to consume as a freshly peeled juicy one, right?
Same with cannabis when she’s stored without proper humidity—even in a closed container. When terpenes are gone, all the good stuff goes with them. And that lessens your experience, your enjoyment.
HERE IS WHAT HAPPENS SCIENTIFICALLY
Terpenes are found in of the trichome on the cannabis plant. Trichomes look like mushrooms that are shiny and sticky. As the source of therapeutic, medicinal and recreational compounds, trichomes are valuable. Without proper attention to the holding environment, trichomes, and thus, terpenes can be lost forever. The efficacy of the plant will be significantly diminished and its dollar value likewise reduced.
Trichomes are damaged and terpenes are lost through:
- Evaporation Terpenes totally disappear from the plant, evaporating into the surrounding atmosphere and are lost for any future usefulness.
- Oxidation Trichomes containing the precious THC and THCA are shifted to CBN under the oxidation process and lose efficacy in this form.
- Breakage When flower is too dry, trichomes become brittle and snap off.
All three can be prevented—or at least minimized—with proper humidity control. Simply storing flower without this protection in an airtight container is not effective.
PREVENTING THE LOSS OF TERPENES
Research into this deterioration identified that a monolayer of moisture on the surface of the trichomes blocks these harmful end results from occurring.
The monolayer accumulates the water layer by layer. At this point, thick layers of water can block the oxidation process and terpene evaporation losses. The monolayer becomes a protective shield that slows down the losses. And when the relative humidity (RH) in the surrounding atmosphere is between 55-65%, flower achieves equilibration with the adjacent air, which dramatically slows evaporation.
Because the air in the headspace of the container now has sufficient water molecules, there’s little room for the terpenes. So those terpenes remain inside the trichome until they’re released by the consumer by grinding, smoking, breaking, etc.
RELATIVE HUMIDITY (RH)
The physical loss of trichomes dropping off buds can be caused by the condition of the atmosphere surrounding flower.
Maintaining a 55-65% relative humidity (RH) range minimizes this loss as flower is handled and moved through the latter stages of curing.
IF YOU SMELL THE TERPS BEFORE GRINDING, IT’S AN ISSUE
Often consumers judge the quality of cannabis by the presence or absence of a positive aroma.
If the aroma of flower is strong hours or days before it’s even ground, there’s an issue. Remember terpene aromatics are in the trichomes. So an intense aroma in unground flower means those trichomes have started to deteriorate and terpenes have evaporated.
When the majority of the terpenes have been preserved, you’ll notice a much more robust and positive aroma when you grind flower.
HUMIDITY CONTROL RECOMMENDATIONS
Many studies have shown that storing flower in the 55-65% RH range ensures ideal end results by preserving terpenes. There are a number of products available that tout their ability to maintain a given humidity level for flower. Issues arise when these products are required to either give off or absorb moisture during the holding stage. Only a saturated salt solution has the capacity to manage a variety of conditions that might emerge.
Other products that utilize a fiber pad do not contain the reserve capacity that is present with a saturated salt solution. While the glycerine can target a specific relative humidity, when it is required to absorb or give off moisture during this holding/maintaining period, it will quickly move off its starting humidity point labeled on the package.
To obtain the ideal end product, the saturated salt solution developed and patented by Boveda is proven to be the protection that can be depended upon under widely varying conditions.
Total terpene content in hemp and cannabis (broken out by terpene type) were reported by Hazekamp etal; Cannabis and Cannabinoid Research 2016, 1.1. http://online.liebertpub.com/doi/10.1089/can.2016.0017.
BOVEDA had ASPEN Laboratories (Aspen Research Laboratories report A52958, issued to Miles Knutson on 2/28/2019 and updated 4/3/2019) analyze hemp samples in sealed containers with and without humidity protection. The report clearly shows that increasing the headspace relative humidity dramatically reduces the terpenes evaporated to the headspace with the highest BOVEDA protected level RH level tested showing the least loss to headspace (see figure 1). Further, Aspen Laboratories (Aspen Research Laboratories report A52771 issued November 30, 2018) showed that of the reduced amount of terpenes in the headspace over cannabis, only a trace was transferred to the sachets. Conclusions drawn from this data are summarized in a report (Equilibrium Balances of Terpenes over Cannabis and Hemp, Jonathan W. DeVries, DeVries & Associates, dated June 8, 2019 and submitted to BOVEDA June 10, 2019).
Increasing RH resulted in less terpene oxidation. Going from 15% RH to 42% RH resulted in a 20-25% reduction in terpene oxidation https://www.diva-portal.org/smash/get/diva2:142965/FULLTEXT01.pdf Pommer, L., Oxidation of terpenes in indoor environments; A study of influencing factors, 2003, Printed in Sweden by VMC, KBC, Umeå University, Umeå . ISBN 91-7305-313-9.
Terpene changes: https://www.researchgate.net/publication/222615960 Calogirou, A, Richter Larson, B, Kotzias, D, Gas-phase terpene oxidation products: A review, 1999, Atmospheric Environment 33(9): 1423-1439, DOI: 10.1016/S1352-2310(98)00277-5.