Cannabis Drying: What Appearance and Aroma Reveal

Comparing cannabis drying methods: What the study shows

Mallis and colleagues published their peer-reviewed paper on 14 October 2026 in the Journal of Cannabis Research as a preliminary publisher version. They compared freeze-drying, oven-drying and drying under controlled vapor pressure deficit, or VPD for short. Huckleberry flowers were examined, with three biological replicates for each treatment. 

Freeze-drying preserved the green color and the external trichome structure particularly well. At the same time, the yield of analytically extracted essential oil was lower. The profile of volatile compounds also shifted. The VPD variant produced the highest oil yield. With oven-drying, the team observed more pronounced changes in color and structure. 

The cannabinoids were comparatively stable, but not unchanged. The authors also report lower THCA values for freeze-dried material. A blanket statement that “THC remains the same” would therefore be inaccurate. 

Fewer aromatic compounds do not automatically mean less aroma

The study analyzed flower constituents and characteristics. It does not report a sensory comparison by an aroma or taste panel. A lower yield of extracted essential oil therefore does not automatically mean a correspondingly weaker aroma. A single cultivar does not permit a general conclusion about all freeze-dried cannabis flowers. 

This leads to an important distinction when assessing a batch. We can describe what a flower looks like. We can assess its aroma. We can also have it analyzed to determine which compounds a sample contains. Only when we clearly distinguish these observations can we meaningfully connect them.

Freeze-drying: What earlier research adds

A study by Spadafora and colleagues from 2024 also compared different drying and storage conditions. The team combined the analysis of volatile compounds with separate cannabinoid analysis. Under the conditions tested there, freeze-drying preserved the cannabinoid content well and limited the conversion of acidic cannabinoids. At the same time, volatile compounds that contribute to cannabis aroma were lost. 

This is a useful comparison, especially because the results are not identical in every detail. Preserving one group of compounds does not tell us how well another group is preserved. A method may perform well for one property under investigation and less well for another. 

That is why “gently processed” is too imprecise as a quality statement. Gentle with regard to which constituent? Demonstrated by which analysis? For which starting material? Such follow-up questions are justified when making a scientifically based quality claim. Naming the method does not replace an assessment of the finished product.

We cover how to store your flowers after drying in our article How to store cannabis properly.

Why terpenes do not explain cannabis aroma on their own

Even a detailed laboratory report cannot be read like an aroma description. In a study published in 2025, Isaacson and colleagues developed a vocabulary of 25 terms to describe cannabis aroma. A panel assessed 91 samples. Although the chemical terpene profiles formed groups, they alone were poor predictors of the perceived aroma character. 

This study examined the aroma of unburned flowers. It was not a taste test during consumption and did not assess medical effects. Its value lies in considering chemical composition and human perception together. Having a terpene profile therefore provides additional information. It does not make an actual aroma description of the sample unnecessary. 

There are also groups of compounds beyond terpenes. André and colleagues quantified four odor-active sulfur compounds in five hemp cultivars. Their work highlights the importance of such thiol compounds for the complex flower aroma. A list of selected terpenes does not automatically capture these compounds. However, this also does not mean that the entire aroma could be explained solely through sulfur compounds. 

For the way we talk about cannabis, this means that “terpene-rich,” “strong-smelling” and “pleasant” are different statements. In a measurement, we are interested in the quantity of compounds detected. In an aroma description, we are interested in the perceptible impression. Whether that impression is enjoyable is yet another separate question.

Read more about the diversity of this group of compounds and the limitations of a small number of laboratory values in our article about 227 terpenes in cannabis.

Assessing cannabis quality: Appearance, aroma and laboratory values

At CannaSelection®, we want to make verifiable statements about a specific sample. A beautiful image can document its visual condition. However, it should not make a statement about an aroma that no one can perceive in the image.

An aroma description becomes more valuable when it is specific. Which notes can be detected? How intense does the impression seem? Do several assessors agree? A simple “smells premium” is less useful to readers than an understandable description that also allows for differing impressions.

Laboratory data should make clear which batch they refer to and which compounds were actually analyzed. A selected value answers a selected question. Our editorial assessment should make this boundary visible and name complementary observations accordingly.

Conclusion: A beautiful image is a beginning

We do not need to downplay attractive appearance. It may be pleasing and it may be part of an assessment. The problem arises only when appearance silently becomes a complete quality promise.

The most interesting discussion therefore begins after the first glance. What do we actually perceive? What was measured? Where do expectations fill a gap? Asking these questions makes it possible to describe flowers more precisely and assess quality claims more effectively.

Have you ever had a flower whose aroma did not match its appearance at all? We would like to know what surprised you about it.

Sources and limitations of the studies

As of: 21 October 2026. Source 1 is available as a peer-reviewed preliminary version. The study was partially funded by HECAGEN. The authors declare no conflicts of interest. [1] The illustrations in this article are original editorial illustrations and are not figures from the studies.

1. Mallis et al. (2026): Post-harvest drying determines cannabinoid and volatile composition in pharmaceutical cannabis (Cannabis sativa). Journal of Cannabis Research. Peer-reviewed preliminary version dated 14 October 2026.
2. Spadafora et al. (2024): The influence of drying and storage conditions on the volatilome and cannabinoid content of Cannabis sativa L. inflorescences. Analytical and Bioanalytical Chemistry.
3. Isaacson et al. (2025): Beyond potency: A proposed lexicon for sensory differentiation of Cannabis sativa L. aroma. PLOS One.
4. André et al. (2026; online 2025): First Quantitation of Key Odor-Active Thiols in Flowers of Different Hemp Cultivars Using HPLC-MS/MS. Journal of Agricultural and Food Chemistry.