Volatile sulfur compounds are small aroma molecules containing sulfur, such as thiols, sulfides and thioesters. Oswald et al. (2021, ACS Omega) used two-dimensional gas chromatography with sulfur detection to identify a family of prenylated VSCs in cannabis. The most important, 3-methyl-2-butene-1-thiol (prenylthiol), was the main driver of the "skunk" aroma.
In practice
VSCs occur at trace concentrations, far below the 1-3% w/w total of the terpenes, but human odour thresholds for thiols are extremely low, so tiny amounts dominate the smell. That explains why two flowers with near-identical terpene panels can smell very different. The same group reported VSC levels rising late in flowering and into curing and falling during storagebeing reviewed. A follow-up (Oswald et al. 2023) found that minor non-terpenoid compounds drive many distinctive "exotic" aromas.
Don't confuse with
- Terpenes: the bulk aroma class, but not the source of skunk.
- Sulfur nutrition: feeding more sulfur has no demonstrated effect on VSC levels.
Myth check
"Extra sulfur feeding makes buds skunkier" has no controlled evidence. See sulfur and Mythbusters.
