Researchers believe they may have identified the chemical primarily responsible for complaints regarding the smell of some marijuana and hemp cultivation operations.

We recently mentioned complaints in connection with the smell of hemp farms – some of them anyway – are far from being uncommon. But it turns out what has been described as a “skunky-like” odor may have nothing to do with certain terpenes, the aromatic compounds found in many plants previously thought to be responsible.

A research team consisting of Byers Scientific, Iowa State University and Texas-based odor experts used a triangulation approach of analytical chemistry to potentially identify the primary culprit as being 3-methyl-2-butene-1-thiol (321 MBT). This compound is among seven contained in a skunk’s spray that give the critter its smelly reputation.

321 MBT is also the same chemical causing the skunk-type aroma and odd flavour in “light-struck” beer. This occurs when beer is exposed to strong light, which causes certain compounds in hops to degrade. Light-struck beer is also known as “skunked” beer and is one of the reasons beer is usually stored in brown rather than clear or green bottles, as brown glass transmits less visible light.

There’s a connection between hops and cannabis – they are in the same plant family (Cannabaceae).

But the 321 MBT discovery isn’t the end of the story – the researchers say identifying the chemical is only the first step in addressing the issue, and efforts are continuing to further evaluate the odor and the most appropriate manner of mitigation. The researchers note other compounds in cannabis’s gas-phase emissions and reactions in the atmosphere “may significantly affect the perception and measurement of 321 MBT.”

Additionally, it seems not all hemp farms stink – and this may be key in developing varieties that contain the required level of desired chemicals or other attributes and less of the undesirable such as 321 MBT.

Trivia: while the term “skunk” is sometimes used to describe the smell of cannabis, it can also refer to all high-THC strains of marijuana in some parts of the world.