A wine connoisseur may be able to name the grape in their wine based on how “horse sweaty” it smells, while some coffee fanatics can sniff out a bean by the level of “cardboard” in its aroma, but how much can smell tell us about different cannabis strains? For instance, is it possible to determine the strength of a particular plant from its scent, and can individual cultivars be identified purely by their aroma?
The first thing to mention is that the pungency of a marijuana plant has nothing to do with its THC concentration, as cannabinoids are nonvolatile compounds, meaning they don’t readily vaporise in the air and are therefore odourless. Even sniffer dogs can’t smell THC, and are instead trained to identify cannabis by detecting a terpene called caryophyllene oxide.
Despite THC’s lack of smell, there are plenty of other compounds in cannabis that are highly fragrant. In general, the aroma of a plant is believed to depend on its terpene composition, although research has shown that other types of volatile compounds – some of which are present in tiny amounts – can often have a massive influence on the overall odour of a plant. One study found that the ingredient with the biggest impact on cannabis aroma is actually a benzene called benzaldehyde[i], which is much less abundant than many terpenes, and which, incidentally, is the principal ingredient in almond-flavoured extracts commonly used in baking.