More cannabis cultivators are turning to decontamination technologies in the wake of increasingly stringent testing regulations, including new stipulations on shelf life, microbial contamination, and kill-step method declaration on post-harvest product labels. 

For cultivators to pass these tests without sacrificing quality requires a process differentiation; using treatment technology capable of achieving high percent kill without sacrificing potency and quality. That’s where our WillowPure system comes in — leveraging ozone treatment to effectively clean your cannabis while preserving terpene and cannabinoid potency.

Key considerations around clean cannabis for cultivators

Increased competition, declining product prices, and quality challenges like pest control and microbial contamination already impact the profitability of cannabis businesses — and failed tests or recalls can result in additional financial losses or inferior products for sale. So, considerations like safety and quality are imperative for cannabis businesses to address in order for them to thrive in a competitive market. Potency degradation is regarded as one the most valuable opportunity costs when cannabis goes through the process of remediation, as terpene and cannabinoid potency loss affect both quality and the bottom line.

According to a Global Cannabis Market Industry Report (forecast period: 2020 to 2026), the most successful players in this space are manufacturers that provide solutions that allow cannabis products to surpass safety standards while maintaining product integrity. Ozone treatment offers a quality-driven approach to cleaner cannabis and addresses microbial contamination concerns that can ultimately help businesses maintain profitability and a positive reputation. 

Ozone treatment as a viable decontamination method

Ozone’s oxidizing effect disrupts cell membranes, leading to microbial death. WillowPure systems gently expose post-harvest material to gaseous ozone for a prescribed duration, reducing microbial contamination on cannabis products without compromising product quality.

It’s recommended to expose cannabis products for four to six hours to ensure a complete permeation of ozone throughout the entire bulk of the product. This is especially important if the initial contamination levels are unknown or if the product is already known to be contaminated. More exposure time is also recommended for a product that is wet, dense, old, or exposed to unclean environments and any other properties that would suggest that the product likely harbors more microorganisms than is typical.

You can evaluate the effectiveness of ozone treatments through a measurement called log reduction, which describes microbial population decreases with one “log reduction” equating to a tenfold decrease. Longer ozone exposure times will result in higher log reductions and percent kill rates. 

Understanding the effect of ozone on trichomes

Trichomes are found on the surface of female cannabis flowers and contain active compounds like terpenes and cannabinoids that characterize the flavor and psychoactive properties of the plant. Naturally, the most common objection to ozone treatment is the misconception that trichomes are damaged by ozone exposure. Cultivators mention organoleptic properties (taste, smell, look) and potency loss as their biggest concern when using remediation technologies. 

At first glance, it may seem intuitive since trichomes have membranes that are susceptible to oxidation. However, the results of this study and many other published studies across different scientific journals show that potency loss does not significantly occur, possibly due to the plant’s natural protective abilities. One study explains that trichomes have a function of protecting plants from oxidative stress that would otherwise be fatal to single-celled organisms such as bacteria, yeast, and mold.

Representative photos of a pre- and post-treatment (6-hour run) from a WillowPure 360 illustrate what happens after ozone exposure. In both samples, the number of trichomes present does not reduce, although the post-treated flower exhibit crystallization and elongation of trichomes. Ozone reacts with water to form hydroxyl radicals, which are powerful molecules that have even greater ability to kill microorganisms on contact. Some drying does occur as surface water reacts with ozone, which concentrates the terpene and cannabinoid content slightly, thus appearing whiter and more crystalized. Visually, the structures remain intact, including the number of trichome heads.

Stereo microscopy of pre- (Fig. 1, left) and post-treatment (Fig. 2, right) using WillowPure 360 (control vs. 4-hour exposure). Visually, trichome heads are preserved, and ozone exposure appears to have a slight crystallizing effect on the trichome, appearing more opaque.

Trichomes experience the most significant physical changes during curing and drying, which is why rapid drying is disadvantageous. The most terpene loss occurs when there is still water in the plant, as terpenes are light molecular compounds that co-evaporate with water. When the trichomes are no longer wet, further loss is unlikely to occur as the membrane becomes more solidified.

There are concerns from some cultivators regarding the perceived loss of smell of post-treated cannabis, but the loss is only from already evaporated compounds lingering in the air and not those that are still preserved in the flower. Although the initial smell may disappear when these free molecules react with ozone during treatment, over a short period of time, the fragrance will come back as some terpenes will naturally evaporate again — as is the nature of volatile organic compounds (VOCs) such as terpenes, which are very light molecules that readily escape into the environment. Those that have already escaped the flower have no practical use other than fragrance, which is why the actual terpene and cannabinoid content still intact within the flower is what matters, especially when it comes to the Certificate of Analysis (COAs) and what we strive to discuss further.

Ozone treatment study with WillowPure

To investigate universal assumptions regarding terpene and potency loss, we collected data from independent cannabis cultivators who regularly test for terpene content and cannabinoid potency, and sampled both pre- and post-treatment as a pair. We collected these paired samples at varying treatment exposure times according to their own processes and submitted these samples to 3rd party laboratories for potency analysis.

Statistical significance and p-value explained

These paired data were then collected and aggregated into a paired T-test statistical analysis to confirm that ozone is a viable method to remediate cannabis without compromising terpene and cannabinoid potency. Any statistical analysis where p-value is higher than 0.05 means that the difference between the two values being compared is statistically insignificant, or has a very small difference between them. If the p-value of the statistical analysis is less than 0.05 (typically written as ≤ 0.05) then it means that it is statistically significant because the confidence interval is 95% or greater. 

In terms of notation, the symbol ‘N’ signifies the total number of samples in the population. ‘M’ denotes mean, or the population average. Standard Deviation or ‘SD’ measures how much each of the data points are close to the mean. A small SD means that overall, each of the data points are more or less the same values, and a large SD (greater than 1) means each of the data points vary widely from each other and likely have a lot of variability. Data points that have a lot of variability from the mean are less reliable because they are less precise and harder to generalize.

THC potency results

In one study, we took an average of individual THC potency data points (N=60 paired sets) and concluded that in the cannabinoid data of untreated vs. treated, overall statistical results of the paired T-test indicated that there is a non-significant, very small difference between Control (M = 19.6, SD = 4.8) and Treated (M = 19.4, SD = 4.2), t(60) = 0.4, p = .665. P-value is higher than 0.05, therefore statistically insignificant difference.

These samples are from anonymized data sets of THC content averages comprised of WillowPure pre- and post-treatment runs (N=60 paired data points) from several participant cultivators and analyzed by 3rd party laboratories, showing negligible potency loss across a wide range of treatment time, and some gain of potency likely due to concentrating the THC content as ozone uses up water molecules.

Terpene content results

In another study, terpene data points were analyzed from terpene compounds that are typically listed in COAs. We collected 329 paired sets, pre-and post-treatment results from 2, 6, 16, and 24 treatment exposures.

We averaged individual terpene data points (N=329 paired sets) and concluded that in the terpenoid data of untreated vs. treated, overall statistical results of the paired-t test indicated that there is a non-significant very small difference between Control (M = 0.1 ,SD = 0.3) and Treated (M = 0.1 ,SD = 0.3), t(329) = 0.07, p = .948 (Fig. 2). P-value is higher than 0.05, therefore statistically insignificant difference.

Anonymized terpene content average comprised of WillowPure pre- and post-treatment runs (N=329 paired data points) from four participant cultivators and analyzed by 3rd party laboratories, showing negligible terpene losses at 2-hr run time, and no terpene losses from 6 hours and beyond.

Terpene composition results

This terpene data has a robust sample population, although we collected the most data points from cultivators who exposed their cannabis flower for 24 hours. Although this does not affect terpene profile, we advise against this unless absolutely necessary because some drying may occur, depending on the starting moisture content of the material.

In all cases, there are no drop-offs, or instances where an entire species of terpene compound disappears entirely from the post-treatment sample. This is an important observation because we can conclude that there is no significant conversion of terpenes into other VOCs and molecular compounds. This is an especially important aspect of quality assurance, as remediation technologies involving chemical reactions must be investigated for potential reactions happening on a molecular level.

We averaged an average of individual terpene data points (N=329 paired sets) and concluded that in the terpenoid data of untreated vs. treated, overall statistical results of the paired-t test indicated that there is a non-significant very small difference between Control (M = 0.1, SD = 0.3) and Treated (M = 0.1, SD = 0.3), t(329) = 0.07, p = .948 (Fig. 3). P-value is higher than 0.05, therefore statistically insignificant difference.

Individual terpene composition of this sample shows that there is no significant difference between the pre- and post-treatment percentage, suggesting that there is low likelihood of VOCs degrading into other compounds and other by-products. If there were degradation, it would show significant loss or complete absence of a terpene compound initially found in the pre-treatment group after ozone exposure.

Key findings of our ozone treatment study with WillowPure

Overall, this study concludes that ozone remediation does not affect terpene and cannabinoid profile of post-treated cannabis products, thereby preserving its medicinal properties, artisanal quality and bioavailability compared to its non-treated counterpart.

Both terpene and cannabinoid data suggest that any ozone exposure treatment times, ranging from 20 minutes to 24 hours, do not result in significant potency change. A slight positive change and increase in terpenoid and cannabinoid potency can be observed in longer ozone exposures, due to possible drying of the biomass, as ozone reacts with water in order to produce hydroxyl radicals, albeit still statistically insignificant. 

This brings up the point of diminishing return component of treatment time in general, as any remediation efforts should take into account the quality of the product both in lessening microbial counts as well as keeping the integrity of the medicinal and artisanal aspect of the plant.

Key data highlights:

  • Paired T-test statistical analysis on terpene potency data points (N=329 paired sets) of untreated vs. treated cannabis, indicate that the difference is not significant between untreated and treated cannabis, sample mean (M) = 0.1, standard deviation (SD) = 0.3, t(329) = 0.07, p = .948.
  • Averaged THC potency data points (N=60 paired sets) conclude that statistical results of the paired t-test show the difference is not significant between untreated (M = 19.6 ,SD = 4.8) and treated (M = 19.4 ,SD = 4.2), t(60) = 0.4, p = .665.
  • Data gathered from cultivators and verified by third-party labs show that ozone does not significantly change the terpene and cannabinoid potency of cannabis flower.
  • Statistical analyses show negligible differences in potency between untreated and treated cannabis.
  • THC and terpene potency remain stable across treatment durations varying from 20 minutes to 24 hours.

Potential implications of ozone treatment for cannabis cultivators

This study, comprised of robust and well-sampled data sets from several cannabis cultivators and processed in their own respective 3rd party laboratories for potency analysis, suggests there is no significant change in potency change due to all T-test statistical tests resulting in a P-value higher than 0.05 for all terpenoid and cannabinoid data sets. This should assure cultivators of choosing WillowPure ozone remediation as a viable choice in reducing microbial loads and passing quality assurance regulations without sacrificing the quality of their product!

Learn more about ozone treatment and our full suite of cannabis decontamination solutions

Think your cultivation space could benefit from ozone treatment? Have more questions about available options? Visit our product page to learn more about the advantages of WillowPure, or contact one of our experts today!