What Makes Cannabis Smell Like… Well, Cannabis?

There’s a lot to say about the smell of cannabis. Its distinct smell, whether freshly ground or combusted nearby, is sure to elicit reactions and comments from those who catch a waft. The smell has been described as unique, dank, loud, and stinky, all of which are typically used to describe the aroma positively. There are common characteristic smells, such as skunk, gas, floral, etc., that people can’t resist the temptation to say “smells good” with a wink when they pass by. On the other hand, you might hear the occasional “Hey, that stinks!”.

There is a particular subjectivity when determining if you enjoy the smell of cannabis, and there is a certain objectivity when it comes to understanding the science of what causes cannabis to smell the way it does. Cannabis’ complex aromas result from the plant naturally producing a combination of compounds from within the plant’s anatomy. In the world of plants, expressing these aromatic compounds is typically the plant’s mechanism for attracting or deterring pollinators or predators, and cannabis plants are no different. Despite this evolutionary defense mechanism to keep predators away, the aromatic compounds in cannabis are what keeps us coming back.

Terpenes

Terpenes are found in all plants and often account for specific scents they emit. In cannabis, terpenes are the most abundant chemical compounds that contribute to a cultivar’s unique aroma. There are hundreds of known terpenes within cannabis, including ones like limonene, which smells like citrus, and myrcene, which gives spicy, earthy scents (Stone, 2022).

As the role of terpenes becomes more understood in the overall experience of cannabis consumption, we can expect that consumers will continue to seek out products that provide them with their desired characteristics. In many cases, terpenes play a significant role in a product’s desirability.

However, cannabis’ aromatic compounds do not end there. In fact, several other molecules contribute significantly to the overall aromatic profile of a cannabis plant. While research is relatively new regarding additional aromatic compounds in cannabis plants, it is something we are starting to see at the front stream of the industry. Cannabis testing labs are working with cultivators to understand the most desirable qualities of cannabis products, and this means looking at all the constituents of a product and determining which combinations lead to product desirability. Frontrunners for the next wave of interesting compounds include thiols, esters, and aldehydes, to name a few.

Thiols

Thiols are chemical compounds containing a sulfur atom instead of an oxygen atom. Their sulfur component is what scientists speculate to be a contributing factor to cannabis' skunk-like aroma, specifically the molecule 3MBT (Byers Scientific, 2022). Interestingly, the same odorous volatile chemical has been reported to produce a similar aroma in light-struck beer (Byers Scientific, 2022).

Esters

Likewise, Esters, known for their role in creating the specific scents of bananas and strawberries (Beekwilder et al., 2004) are also found in cannabis (J, 2016). However, it’s important to note that esters have low boiling points, so they volatilize quicker and high temperatures make them decompose into acrid flavors (J, 2016).

Aldehydes

Aldehydes play a large role in cannabis’ aroma, as shown by Rice and Koziel in their 2015 research article Characterizing the Smell of Marijuana by Odor Impact of Volatile Compounds: An Application of Simultaneous Chemical and Sensory Analysis. They found that aldehydes like acetic acid, a compound that is known for giving vinegar its sour taste and strong smell, and benzaldehyde, a compound that emits an almond-like odor, have large enough concentrations to overpower the impact of terpenes in cannabis’ scent (Oregon CBD, 2020). This also furthers the belief not all aromatic compounds “stink” the same, and that some compounds smell stronger than others. This means that concentrations of aromatic compounds alone do not paint the full picture when it comes to understanding the aromatic building blocks of cannabis (products).

Essentially…

As cultivators, processors, and distributors look to stay one step ahead when bringing new and desirable products to market; they will be forced to navigate and better understand the chemistry of their cannabis plants. This is so that they can ultimately create reliable, high-quality products and keep consumers and medical patients returning for more.

With locations across North America, Steep Hill labs are perfectly positioned to help with every cannabis testing need. We offer extensive terpene and potency testing and are happy to help you on your safe, consumer-friendly cannabis journey. Don’t hesitate to contact us today!

References:

Beekwilder, J., Alvarez-Huerta, M., Neef, E., Verstappen, F. W. A., Bouwmeester, H. J., & Aharoni, A. (2004, August). Functional characterization of enzymes forming volatile esters from strawberry and banana. Plant physiology. Retrieved November 9, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC520758/

Byers Scientific. (2022, May 23). The source of the "skunk-like" Odor in cannabis. Byers Scientific. Retrieved November 9, 2022, from https://byers-scientific.com/cannabis-emissions-and-the-source-of-the-skunk-like-odor/#:~:text=A%20Skunk%27s%20Spray%20Contains%20a%20Thiol%20Also%20Found%20in%20Cannabis&text=The%20human%20olfactory%20system%20has,odor%20detection%20threshold%20(ODT)

J, S. (2016, March 10). Esters: The secrets behind the sweet aromas of cannabis. High Times. Retrieved November 9, 2022, from https://hightimes.com/grow/esters-the-secrets-behind-the-sweet-aromas-of-cannabis/

Oregon CBD. (2020, June 24). Blog: Oregon CBD: The trusted source for feminized hemp seed. Oregon CBD. Retrieved November 9, 2022, from https://oregoncbdseeds.com/blog/?post=are-terpenes-the-sole-source-of-aroma-in-cannabis

Rice, S., & Koziel, J. (2015, December 10). Characterizing the Smell of Marijuana by Odor Impact of Volatile Compounds: An Application of Simultaneous Chemical and Sensory Analysis. BLOS One. Retrieved November 9, 2022, from https://drive.google.com/file/d/1g7TIROK625szw6oxpZosnwzQvyGz4q_3/view

Stone, E. (2022, September 20). What are cannabis terpenes and what do they do? Leafly. Retrieved October 13, 2022, from https://www.leafly.com/news/cannabis-101/terpenes-the-flavors-of-cannabis-aromatherapy