Newly found sulfur compounds in cannabis flowers are responsible for the plant’s distinctive odor.
Scientists have now identified the chemicals responsible for marijuana’s pungent odor.
The pungent aroma that emanates from fresh cannabis is actually a mixture of hundreds of aromatic chemicals. Iain Oswald, an analytical chemist at Abstrax Tech, a private firm in Tustin, California, that creates terpenes for cannabis products, explains that the most noticeable floral, lemony, and piney overtones come from a class of chemicals known as terpenes. However, it’s been difficult to pinpoint the origin of that unique cannabis aroma.
Now, for the first time, a study has identified a set of sulfur compounds in cannabis that are responsible for the skunk-like odor, researchers write in ACS Omega on November 12.
Oswald and his coworkers had a suspicion that the offender would contain sulfur, a pungent ingredient prevalent in hops and skunk spray. On a scale from zero to ten, with ten being the most pungent, the researchers initially rated the skinniness of flowers taken from over a dozen different Cannabis sativa species. Using gas chromatography, mass spectrometry, and a sulfur chemiluminescence detector, the team then generated a “chemical fingerprint” of the airborne compounds that contributed to each cultivar’s distinct aroma.
As hypothesized, the researchers discovered trace levels of a number of aromatic sulfur compounds in the olfactory profiles of the most pungent cultivars. The most abundant chemical was prenylthiol, or 3-methyl-2-butene-1-thiol, which is responsible for the infamous flavor of “skunked beer” (SN: 11/27/05).
The sulfur compounds have been discovered in nature, but never in cannabis, according to Amber Wise, an analytical chemist with Medicine Creek Analytics in Fife, Washington, who was not involved in the research.
Oswald was startled to discover that prenylthiol and several other sulfurous suspicions in cannabis share structural similarities with garlic molecules. Similarly to these alliaceous analogs, a small amount goes a long way.
These molecules “may be present in extremely low amounts on the flower, but have a significant impact on the aroma,” according to Oswald. When cannabis flowers attain maturity and throughout the curing process, sulfur compounds are at their peak concentration.
Avery Gilbert, a smell psychologist at Headspace Sensory, a new company in Fort Collins, Colorado, that specializes in quantifying the numerous aromas of cannabis, is ecstatic about the addition of these compounds to marijuana’s chemical arsenal. “The range of cannabis odor is quite astounding,” he says. I believe it to be superior to wine.
Gilbert states that the finding of prenylthiol in marijuana is the first step in hiding its offensive odor or increasing its perversely delightful stench.
Prenylthiol has a “polarizing aroma,” according to Oswald. Some cannabis consumers will pay a premium for skunky grass, which they perceive to be an indicator of quality despite the fact that many people find it offensive.
