Unveiling the Skunky Mystery: The Science Behind Cannabis’ Signature Aroma

Cannabis is a plant with many facets: it’s a source of medicinal benefits, a recreational staple, and, for many, an olfactory enigma. Anyone familiar with its pungent, skunk-like odor knows it can be as polarizing as it is unmistakable. Recent research published in ACS Omega by Iain Oswald and his team has shed light on the molecular culprits behind this characteristic scent: a new family of prenylated volatile sulfur compounds (VSCs).

The Odor Puzzle

Cannabis sativa L. boasts a complex aroma profile with over 200 known compounds. Historically, research has concentrated on terpenoids, which offer a spectrum of scents from woody to citrusy to floral. Despite their abundance, terpenoids weren’t pinpointed as the source of cannabis’ skunky smell. This led researchers to hypothesize that other molecules, akin to those used by skunks for defense, might be responsible.

Pure sulfur itself has no smell. The stink associated with the element comes from many of its compounds, according to Chemicool. For instance, sulfur compounds called mercaptans give skunks their defensive odor. Rotten eggs and stink bombs get their distinctive aroma from hydrogen sulfide. Similarly, the distinctive seaside smell is caused by dimethyl sulfide (DMS) released into the atmosphere by microalgae.

The Discovery Process

Oswald’s team employed a custom-built, comprehensive two-dimensional gas chromatography system, analyzing flowers from 13 cannabis cultivars with three different types of detectors. A panel of four individuals then ranked the pungency of these cultivars. Among them, Bacio Gelato emerged as the most pungent, housing the highest concentration of VSCs.

Seven VSCs were identified in total, five of which contained the prenyl functional group, notorious for their skunky or sulfuric aromas. The standout compound, 3-methyl-2-butene-1-thiol (VSC3), was most abundant in the cultivars deemed most pungent. Notably, VSC3 is also associated with the aroma of “skunked beer,” a familiar scent to anyone who has experienced beer exposed to UV light for too long.

Confirming the Skunky Culprit

To verify VSC3’s role, the researchers created a blend of VSC3 and ten other major cannabis aroma compounds, closely replicating the characteristic cannabis scent. Furthermore, VSC3 was detected in cannabis concentrates, such as those used for vaping. Greenhouse experiments revealed that the concentration of prenylated VSCs peaks towards the end of the flowering stage maximizes during curing, and diminishes significantly after 10 days of storage.

Beyond Aroma: Potential Medicinal Benefits

Interestingly, the molecular structures of these VSCs, known for their anti-cancer and cardioprotective properties, resemble those found in garlic. This resemblance opens new avenues for investigating the potential medicinal benefits of these prenylated odor molecules. While this research primarily focused on aroma, the implications for health and wellness are promising and warrant further exploration.

The Broader Context of Sulfur

Sulfur has played a vital role in Earth’s history and life itself. It was crucial in creating water on the early Earth by bonding with hydrogen, which later joined oxygen to form water. Sulfur chemistry supported anaerobic life during the Archean eon and was instrumental in oxygenating the atmosphere, contributing to the Great Oxygenation Event (GOE). This event, driven by photosynthesis from algae, cyanobacteria, and plants, enriched Earth’s atmosphere with oxygen, paving the way for more complex life forms.

The rise in atmospheric oxygen enabled higher metabolic rates and faster evolution of life, particularly during the Proterozoic era. Today, sulfur compounds continue to impact the environment, with dimethyl sulfide influencing cloud formation and atmospheric reflectivity.

The Molecular Histories of Smell

While writing this story for Skunk Magazine, I couldn’t help but reflect on my conversation with Swami at Meadowlands. He eloquently explained how there is no smell in the vacuum of space—mainly because it’s sulfur. Before the Great Oxidation Event, there weren’t really any smells on Earth either, as it was dominated by sulfur.

This reminded me of Harold McGee’s book Nose Dive: A Field Guide to the World’s Smells. McGee, a James Beard Award-winning author and leading expert on the science of food and cooking, takes readers on a sensory adventure through the smells of the universe—from the sulfurous nascent Earth to the fruit-filled Tian Shan mountain range, and even to the keyboard of your laptop. McGee’s work highlights how our sense of smell connects us to the molecules that trigger our perceptions, weaving a rich tapestry of the olfactory history of our world.

Like everything in the physical world, molecules have histories. Many of the molecules we smell every day existed long before any creature was around to smell them—before there was even a planet for those creatures to live on. Beginning with the origins of those molecules in interstellar space, McGee moves onward through the smells of our planet, the air and the oceans, the forest and the meadows and the city, all the way to the smells of incense, perfume, wine, and food.

Here is a story of the world, of every smell under our collective nose. A work of astounding scholarship and originality, Nose Dive distills the science behind the smells and translates it, as only McGee can, into an accessible and entertaining guide. Incorporating the latest insights of biology and chemistry and interweaving them with personal observations, he reveals how our sense of smell has the power to expose invisible, intangible details of our material world and trigger feelings that are the very essence of being alive.

Synergy in Nature and Beyond

There’s so much synergy in these discoveries. I recently watched an episode of Mayim Bialik’s podcast, Breakdown, featuring Deepak Chopra. He spoke about how our bodies exchange molecules with all sentient beings through eating, breathing, digestion, and metabolism. Chopra emphasized the idea of one mind, one body, and one consciousness—a deeper reality where love is not just sentiment but the ultimate truth of interconnectedness.

As a writer for Skunk Magazine, I believe in the synergy of knowledge and experience. The exploration of cannabis’ aroma, the history of sulfur on Earth, and the philosophical insights on interconnectedness all contribute to a richer understanding of our world. These stories remind us that every aspect of our existence, from the smell of a skunk to the formation of water on Earth, is intertwined in the vast tapestry of life.