Avery Gilbert and the Terpene Revolution

He's calling the terpene revolution "the nucleus of the brand new field of cannabis psychophysics" (First Nerve, Feb 2021) and I can't argue because he is the first, and when you're the first, you get to name things.

Here's a quick run-down of Avery Gilbert's work circa terpenes since 2018. (Note that he was the first person to get federal approval for olfactory research on pot.)

Consumer perceptions of strain differences in Cannabis aroma, Feb 2018

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0192247

The smell of marijuana (Cannabis sativa L.) is of interest to users, growers, plant breeders, law enforcement and, increasingly, to state-licensed retail businesses. The numerous varieties and strains of Cannabis produce strikingly different scents but to date there have been few, if any, attempts to quantify these olfactory profiles directly. Using standard sensory evaluation techniques with untrained consumers we have validated a preliminary olfactory lexicon for dried cannabis flower, and characterized the aroma profile of eleven strains sold in the legal recreational market in Colorado. We show that consumers perceive differences among strains, that the strains form distinct clusters based on odor similarity, and that strain aroma profiles are linked to perceptions of potency, price, and smoking interest.

Use of rating scales versus check-all-that-apply ballots in quantifying strain-specific Cannabis aroma, March 2019

https://onlinelibrary.wiley.com/doi/abs/10.1111/joss.12499

Previous research using a check-all-that-apply (CATA) method to describe the strain-specific aroma of dried Cannabis flower revealed two major clusters, one characterized as woody, earthy, herbal and the other as citrus, lemon, sweet, and pungent. In this study, participants rated 10 strains (including seven strains not previously tested) using numeric rating scales and a slightly smaller set of odor descriptors. The results confirm the two major scent clusters, and indicate a possible intermediate cluster differentiated by a skunk note. We observed systematic variation in the use of descriptors and rating scales: evaluators who used more odor descriptors tended to assign higher scale ratings. Nevertheless, the CATA and rating scale methods yielded similar results.

Human olfactory detection of packaged cannabis, March 2020

https://www.sciencedirect.com/science/article/abs/pii/S1355030619302047

Olfactory detection of cannabis aroma by police officers can be the basis for warrantless searches of motor vehicles in many jurisdictions in the United States. The odor source in these cases is often dried cannabis flower contained in various casual wrappings as well as in more elaborate packaging. Here we investigate whether packaging format alters the detectability of the cannabis. Two cannabis strains and five packaging formats were evaluated. Untrained observers were presented with two containers and asked to identify, based only on smell, the container that held a sample of packaged cannabis (the other container held identical, but empty, packaging material). The results showed that open and casually packaged cannabis was identified with high accuracy, while material packaged in doubly vacuum-sealed plastic was correctly identified at rates no different from chance. The results may help address issues involving the detectability of cannabis aroma in law enforcement and other scenarios.

At Your Fingertips

Condom-detecting fingerprint test 'set for court use'

Oct 2017, BBC

"[Your fingerprint] contains molecules from within your body but also molecules that you have just contaminated your fingertips with, so the amount of information there potentially to retrieve is huge."

-Dr Simona Francese of Sheffield Hallam University for the BBC

And this information is now set to be used in courtrooms.

It comes as a surprise to me that this technique is only being used now. We've known since the dawn of the microscope that the labyrinthine ridges of our fingertips are stuffed with bacteria and whatever else in the world we recently touched. We've also been using this mass spectrometer tool since the 1900's, which is also when fingerprinting itself came out.

I’m adding this to the archives here because the mass spectrometer, combined with the gas chromatograph, is the primary tool for detecting odorous molecules. It’s the closest thing to an artificial nose that we have, and it’s the only we to determine with certainty what’s in a smell.

I’ve added below a chart taken from Sigma Aldrich, a supplier of essential oils for the flavor and fragrance industry. It shows the fingerprint, if you will, of the smell of orange.

 

The smell of orange, as seen in gas chromatograph analysis, courtesy of Sigma Aldrich.

As you can see, the smell of orange has in it way more than just “orange.” In fact, there’s nothing called “orange” in there at all. Limonene and Citronellol might sound like they belong there, but the others are probably foreign to most.

image: Imperial College London site, where you can grow your own fingerprint bacteria on an agar plate