What gives weed its unique aroma?

The smell of cannabis is often attributed to its unique terpenes – the aromatic compounds produced by the plant – but they are not the whole story behind cannabis aromas. This becomes clear when you smell two different strains. For example, compare GMO to a cross between Grape Pie x Do-Si-Do: both have similar terpene profiles, but the actual aroma is completely different.

What else contributes to the complex aroma we smell from cannabis? A new paper published by Abstrax Tech helps answer this question.

Abstrax Tech’s research into what gives weed its aroma

Researchers at Abstrax Tech examined 31 strains of ice water hashish, a solvent-free extraction that separates the trichomes from the rest of the cannabis plant, and rated them from sweetest to savoriest smell. The samples, many of which were produced by 710 Labs, were divided into three categories: sweet-exotic, prototypical (average-smelling cannabis), and savory-exotic.

The strongest-smelling varieties were further studied to find out what compounds were produced that might be responsible for the more pungent aroma. The results showed that the different flavors are due to various unique compounds such as alcohols, esters, aldehydes and more, which produce aromatic profiles ranging from fruity to sweet, tropical or chemical.

Courtesy of Abstrax Tech

The sweet exotic cannabis strains that smelled most citrusy often contained a new class of tropical volatile sulfur compounds, or “tropicannasulfures.” These are varieties such as Papaya, Guava or Tangie, where this deep citrus scent is obvious.

Varieties that are considered more palatable, such as GMO and Chemdawg, contain a compound called “skatole.” Skatole occurs naturally in feces – particularly the feces of mammals and birds – and is partly responsible for that fecal smell. However, at the small amounts found in cannabis, it takes on a completely different savory, tingling and gassy aroma.

In both the sweet and savory cases, it is not just one molecule that imparts the bud’s unique aroma, but rather a complex interplay of dozens, if not hundreds, of aromatic compounds that create a unique scent.

Newly discovered aromatic compounds in cannabis

In addition to sweet and savory, there are also other cannabis flavors such as floral, fruity, creamy and chemical, whose smell is determined by unique compounds. These other compounds that contribute to aroma alongside terpenes and terpenoids are called “flavorants,” not to be confused with “flavonoids,” which give purple cannabis its color.

Flavors include esters as the main driver of the fruity smell, with some strains like Banana Scream having over 15 unique esters contributing to the aroma. Abstrax Tech’s research is the first time that these small molecules can be directly attributed to the smell of cannabis and creamy-sweet strains.

A flower’s terpene profile is often used to represent predicted smell and indicate the effects of a particular strain. However, it is clear from this current research that many other compounds besides terpenes contribute to the complex aroma of cannabis. Although these other aromatic compounds are not typically tested in the laboratory, your nose may be the best tool for detecting these smells, as the nose contains over 400 olfactory receptors that can detect an estimated one trillion scents.

It is thought that, similar to terpenes, these aroma compounds also produce some biological activity that may contribute to the unique effects of different strains. For example, the study authors identified indole and skatole as responsible for some of the savory and chemical smells of cannabis. These compounds are very similar to both the compounds our bodies make and other compounds in nature known for their anti-cancer properties and their effects on the cannabinoid 2 receptor.

Future research will begin to test the potential therapeutic benefits of these newly identified compounds in the plant.

5 insights from Abstrax Tech’s recent research

There is much more to the aroma and effects of cannabis than just its terpene content. Here are five key findings from Abstrax Tech’s research:

1. The smelly compounds that give cannabis its unique smell are called aromatics.

We usually attribute terpenes to giving different cannabis strains their unique smell. Terpenes are only part of the story, but additional aromatics such as aldehydes, esters and alcohols also contribute to the diverse and unique flavors.

2. Terpenes have no direct connection to the smell of exotic cannabis strains, but in combination with flavor compounds can be helpful in characterizing subclasses of cannabis.

Terpenes are still important and likely represent unique subclasses of flavors. For example, limonene-dominant strains with unique flavor compounds may have a similar flavor but differ greatly from caryophyllene-rich strains with similar flavor compounds.

3. A new class of compounds called “tropicannasulfure” is responsible for the sweet/citrus strains of cannabis, and skatole (the fecal molecule) gives savory strains their unique, funky smell in low concentrations.

Volatile sulfur compounds (VSCs) are key odor drivers and contribute to the smelly smell of many varieties. A new class of VSCs called tropical volatile sulfur compounds, or “tropicannasulfures,” contribute to the citrusy and sweet smell of many exotic cannabis strains. Skatole is responsible for the unique smell of feces, but in the very low concentrations found in cannabis, it can produce strange, earthy and chemical smells.

4. Limonene is one of the worst terpenes at predicting the taste and smell of a strain.

Limonene is perhaps one of the worst compounds to put on a label if you want to predict what a strain will taste or smell like. When it comes to limes, varieties with rich, savory flavors or light, lemony flavors often dominate. This terpene is not a reliable indicator to predict the effects of a strain. So rely on your nose for the best results.

5. Terpinolene-rich varieties are among the few varieties that can be reliably identified based on their terpenes alone.

Terpinolene-rich strains are known as typical “sativas”, such as Trainwreck, Jack and many Hazes. These terpene profiles are among the only ones that could be differentiated based on terpenes alone. While other strains with dominant terpenes like myrcene, caryophyllene, and limonene can produce very different flavors, terpinolene strains tend to be similar and more easily recognizable.