While many attribute cannabis’ skunky smell to compounds like terpene, its cause remained a mystery — until now. Photo credit: Rawpixel.
Cannabis plants and buds have a strong, skunk-like smell that some find enjoyable but others find revolting. Whether someone likes the aroma or not, it’s one of cannabis’ most distinguishing factors. Now, researchers think they’ve discovered just exactly what creates this scent.
While many attribute the plant’s odor to a variety of terpenes; the latest research on this topic has revealed a new class of volatile sulfur compounds (VSCs). These compounds give cannabis its distinctive skunky odor, according to a study published by ACS Omega. Researchers believe that this discovery opens lots of new possibilities for further exploration of the compounds’ therapeutic potential.
What Does the Study say?
Before, experts didn’t know which of the hundreds of metabolites found in cannabis gave the flower its skunky smell. According to the recent study, during which researchers analyzed 13 different cannabis strains, they found that a group of never before discovered VSCs — which closely resemble those found in garlic — caused the odor.
Graphic pulled from study in the ACS Omega journal.
Researchers tested and evaluated the numerous strong-smelling compounds they discovered in cannabis flowers as well as concentrated cannabis extract to determine the chemical origins of the smell.
In the process, scientists were especially exploring VSCs. These are also present in skunk spray and stinky vegetation like garlic and hops.
The analysis eventually uncovered a slew of new VSCs related to the signature cannabis scent. The compounds, identified as VSC3 through VSC7, all have an internal structure similar to garlic VSCs.
“The structural similarities between VSCs in cannabis and garlic thus warrant further investigation to determine if the former possess similar health benefits to those of the latter,” the authors of the study, headed by analytical chemist Iain Oswald, write.
There appears to be a substantial link between VSC3 concentrations and the skunk scent, according to the researchers. They detected other VSCs were at lesser amounts when the skunk scent was present, though the molecules differed between strains. Some were present in only one strain; however, they consistently associated VSC3 with the skunk smell throughout all.
Involvement of Other Chemicals in the Smell
This does not imply that VSC3 is the only one that generates the sulfurous fragrance. The involvement of these chemicals in a smell is complex and based on the presence of other VSCs.
For instance, VSC3 smelled skunky to the researchers at high concentrations. But when the top 10 VSCs were combined in a vial, they evaluated the fragrance as “mildly reminiscent of a [cannabis] flower,” with no “pungent, skunk-like aroma.” However, adding VSC3 at a low, 1% concentration, resulted in an instantaneous odor change, which researchers said “strongly emulated the scent of a [cannabis] flower.”
“Interestingly, although VSC3 evaluated independently had a sulfuric, skunk-like aroma, the combination of the formulation and VSC3 was described most closely to the characteristic scent of cannabis, indicating that the combination of VSCs and other major components combine synergistically to yield this scent,” the study reads.
Researchers also noted that “when the scintillation vial was left uncapped for even short periods of time (∼15 to 20 min), the scent associated with VSC3 was almost undetectable, indicating that this compound volatilizes quickly. These olfactory tests confirm that VSC3 is the primary source of the characteristic scent of cannabis, while the remaining compounds VSC4−VSC7 may further intensify or modulate this aroma.”
Besides that, researchers saw another fascinating observation occur. When they mixed high quantities of VSC3 with VSC5, typically in cannabis extracts, VSC5 tended to make VSC3’s skunky scent much more powerful. This might explain why cannabis extract can be really stinky even after a manufacturer turns the flower into oil.
Some Discoveries During Growing
Before the main stage of the research, scientists grew the future experimental cannabis strains in a greenhouse. During the cultivation process, they discovered that when the plant began to mature, VSCs increased dramatically. They especially noticed that when they cured and dried the flower, these chemicals were at their maximum amounts. VSC concentrations then began to fade after a week of storage.
“In particular, the drop in VSC3 concentration suggests rapid volatilization, which most likely contributes to the extremely diffuse and detectable aroma associated with cannabis,” the research reads.
Ultimately, findings show how complex the volatile compounds in cannabis are. Importantly, the reported VSCs establish the chemical provenance of cannabis’ smell and introduce a new group of metabolites that can be studied for biochemical processes and medicinal benefits.