Research Paper Puts Sensory Evaluation in the Higher Ed Classroom

Armonía (Harmony) by Remedios Varo (1956)

A peer-reviewed paper I co-authored with collaborators at the University of Michigan is published in the current edition of the Journal of Statistics and Data Science in Education (JSDSE). The paper outlines a pilot educational module at the University of Michigan that integrates machine olfaction into an undergraduate deep learning course. By combining chemistry, machine learning, and sensory evaluation, the curriculum challenges students to work with subjective sensory data, demonstrating the feasibility of teaching multimodal data science.

The inclusion of sensory evaluation in a deep learning course is novel as far as papers accepted by JSDSE go. The good news is that our pedagogy-driven endeavor doesn't end with our paper. Dr. Ambuj Tewari received a second New Initiatives/New Instructions (NINI) grant from the University of Michigan that will allow us to take our findings to the next level (which is why I'll be busy teaching this summer). 

Curious? Read the paper and sniff out the facts in the sensory evaluation portion. Readers of Glass Petal Smoke who work in the flavor and fragrance industry will appreciate it. Perfume fans may also find it interesting, and don't have to worry about decoding a research paper. It's all about learning in small incremental steps. The more you do it, the better you get at it.

Citation: Han, Y., Kydd, M. K., Ward, J., & Tewari, A. (2026). Teaching Machine Olfaction in an Undergraduate Deep Learning Course: A Pilot Integrating Chemistry, Machine Learning, and Sensory Evaluation. Journal of Statistics and Data Science Education, 34(3), 372–380. https://doi.org/10.1080/26939169.2026.2665103

Notes & Curiosities

Teaching 100+ students in a large auditorium how to evaluate smells using fragrance blotters was and remains one of the most satisfying teaching experiences I've had at the University of Michigan to date. It proved what I've always known by experience; that sensory evaluation is a powerful multisensory teaching and learning tool when combined with other disciplines. The sense of smell is memory's sense; it doesn't get more pedagogical than that.

I have many students to thank with regard to the evolution of Smell & Tell lectures, especially those that were part of summer boot camps held by MSTEM Academies at the university. Thanks also go out to students who invited me to give a TEDxUofM talk in 2015 (a talk that resonated with a wider audience after the COVID-19 pandemic) and students who shared their anosmia and congenital anosmia stories with me after the event. 

BTW: One of the reasons why Dr. Tewari and I ended up collaborating was the presence of my TEDxUofM talk online; the rest, as they say, is history.

I would be remiss if I didn't thank the Ann Arbor District Library for saying yes to monthly "Smell & Tell" events in 2012, and every year afterward. There isn't a day that goes by that I don’t forget how much creative freedom the library gives me. Honestly, writing this post makes me feel like I'm dreaming with my eyes open.  

Stink, Stank, Smellmatize (Eau Ferula)!

Wheel of aromatic ferula resins or secret stink device?

Teaching people how to evaluate the smell of an unknown material on a perfume blotter requires trust and a sense of adventure. This is true for novices and experienced attendees at Smell & Tell in Ann Arbor, which was highly evident at a recent AI-themed program.

The sense of apprehension that’s experienced before blind smelling an odorant is a reminder of the underlying purpose of smell, which is to protect us from danger (and encourage behaviors that lead to survival like eating, and sniffing out desirable qualities in a mate).

Hemulen, a character in Tove Jansson's Moomins series, gave up stamp collecting for botany. You can smell his tabula rasa mindset. 

Blind smelling requires a tabula rasa mindset, so you can sense the character of a thing. It's not about whether you love or hate a smell. The smell exists irrespective of your opinion of it. Your job, in real life and at Smell & Tell, is to interpret what your brain is interpreting through your nose. 

The tendency to seek visual proof for non-visual sense objects gets in the way of being fully present for an experience. Smells that are polarizing are challenging to evaluate, but it's important to give smells a chance because what you notice at first sniff changes as it evaporates—and some smells transform in fascinating ways.

Once in a while, I throw a polarizing nose surprise into a Smell & Tell lecture that pushes a contextually relevant button. It’s not done for the sake of theater (a mixed chorus of "icks" and expletives that are the inevitable result of encountering something less than pleasant). 

"Green Wheat Fields, Auvers" by Vincent Van Gogh

When attendees experience a shapeshifting smell from start to finish, they're more than surprised; they're elated. This reaches beyond the fact that the fragrance blotter no longer smells unpleasant. It's proof that patience is worth the time it takes to understand the essence of a thing—because you might learn something new. 

Case in point. A two-year old asafoetida tincture was smelled at Smell & Tell: AI, Machine Learning & Smells last month. The material, which was the sixth and final material in the scent flight, had a nose wrinkling reputation with a twist. Attendees were in for a surprise after class.

The smell in Asafoetida that reminds humans of sulfur, garlic, and onions changes over time. This particular tincture possessed more than the balsamic vanilla drydown noted by Steffen Arctander. It smelled sweet, citrusy, floral-rosy, musky, powdery, orris-like, and citrusy (lemon).

This, dear reader, explains the wheel of ferula resins that accompanies this post. They are part of a tincturing project that informs a future Smell & Tell lecture on the ferula family of scents. I was inspired by an email I received from author Alex Kourvo who attended last month's event. The subject line read “What is this magic?” and continued with:

Smell and Tell was sooooo fun on Wednesday! All the smells were interesting and as always, I felt like my brain grew two sizes. I was amazed that the blotter that had asafoetida on it smelled so much better the second day! I almost threw it away instead of taking it home because it smelled so awful at first. But on day two, it was almost like a perfume. And on day three, it's still pleasant. How. How. How?

Alex's question is an important one that resonates with comments from other attendees who've attended Smell & Tell at the Ann Arbor District Library since it’s inception in 2012. Humans generally don't expect something beautiful from something that smells unpleasant, but it's possible. That's an experience worth holding onto.

Notes:

Asafoetida was used at Smell & Tell to make a point about avoiding cow pies regarding Artificial Intelligence (AI), human olfaction and neurology. The term “AI" is frequently substituted for "machine learning" by startups on the AI bandwagon. Don't believe the hype. 

Smelling tinctured resins comprises half of the method I use to evaluate scents (the way I was trained a la perfumery). I use a thermostatically controlled incense heater to experience smells that resins release into the air over time as this enjoins perfumery's predecessors; medicine and incense. 

Image of Die Wachauer Nase By Schurdl (CC). The sculpture, one of a series of nose sculptures in Austria, was organized by the Gelitin art collective.

Smell & Tell Event | AI, Machine Learning and Smells!

Spock smells "the spores" and sees the future.

Smell & Tell | AI, Machine Learning and Smells! 

Date: Wednesday, September 20, 2023 

Time: 5:30PM-7:30PM 

Location: Ann Arbor District Library (Downtown) 

Address: 343 S 5th Ave, Ann Arbor, MI 48104 

Phone: 734-327-4200

You really need to think like a Vulcan when it comes to prognostication and AI. The future is unknown and as such is subject to fantasy, ideology and cow pies. This is especially true of the intersection of smell, machine learning, and artificial intelligence. 

Machines that analyze smells aren't new. The pairing of Gas Chromatography with Mass Spectrometry (GC-MS) was demonstrated in 1955-56 by Dow scientists in Midland, Michigan. The technology, which is used to analyze individual components of complex mixtures in analytical chemistry labs, continues to evolve. 

We'll explore eclectic smell terrain and collectively follow our nose to get a better understanding of how humans evaluate smells against the capacity of machines that analyze complex mixtures and their components. 

The Smell and Tell series of art+science programming is led by Michelle Krell Kydd, a trained nose in flavors and fragrance who shares her passion for gastronomy, sensory evaluation and the perfume arts on Glass Petal Smoke. Smell & Tell builds community through interactions with flavor, fragrance and storytelling. 

Notes:

Nose-forward reading for this Smell & Tell program:

More than meets the AI: The possibilities and limits of machine learning in olfaction by Ann Sophie Barwich and Elizabeth A. Lloyd (2022)

Gas Chromatography - Mass Spectrometry via Dow, Inc. and the American Chemical Society.

Sensory Training: Making Friends with Devil's Dung

Opening a container of asafoetida (Ferula asafoetida) will clear out a room. The ground gum oleoresin, which is used as a spice, has a nose wrinkling smell that resembles mercaptan, the rotten cabbage-like odorant used to scent natural gas. Mercaptan and asafoetida contain sulfur compounds associated with decomposition, so why would anyone want to make friends with a spice that's earned the nickname "Devil's Dung"?

Asafoetida is an alliaceous substitute for onions and garlic in Jain cooking. It's also used as an umami flavor enhancer in Indian cuisine and acts as an antiflatulent, which is ironic when one considers how asafoetida smells before it mellows during the cooking process. 

There are aesthetically pleasant things one can study when training their sense of smell, but asafoetida is one of the best because it's a catalyst for discovery when confronting sensory bias. Humans are hardwired to escape dangerous smells, but not all unpleasant smells are dangerous. The challenge in sensory evaluation, inclusive of taste and smell, is the fact that most of us would rather experience something we like and avoid anything we find unpleasant.

When you're going through sensory training you learn to let go of personal preferences and aversions. The goal isn't to become objective because sensory perception is subjective. You learn to become more evaluative in sensory training, which is to say that you assess something for its character—whether you like it or not.

Smelling tincture of asafoetida as it evaporates on a perfume blotter is a revelation. The hellish brimstone odor is transformed as sulfur compounds evaporate and sweet balsamic notes redolent of vanilla emerge in the drydown. The heavenly transformation is striking, counterintuitive and unforgettable. 

Making friends with Devil's Dung (asafoetida) is a catalyst for self-discovery and a great way to conquer sensory bias. It teaches us that something we find unappealing can become a gateway for beauty over time. That's something worth lingering over.

Notes:

Sulfur compounds aren't found in the non-volatile constituents of asafoetida—they're only present in the essential oil. Once the sulfur evaporates from the oil other constituents such as vanillin and ferulic acid in ester form (the later related to ferulaldehyde found in maple syrup) can be detected. Ferulic acid is also related to isoeugenol (found in clove and other plants) and vanillin (found in vanilla). You don't have to be a chemist to recognize the inter-relational quality in plant volatiles on a molecular level. You can smell it.

To make an asafoetida tincture for smelling combine 1.42 grams (1/4 teaspoon) of asafoetida with 4ml of ethanol (high proof vodka) in a 5ml amber glass vial. Keep the tincture in a cool dark place and allow to age for one month. Shake the tincture daily during maceration.

Asafoetida resin sold in spice shops is ground into a powder with gum arabic and neutral materials such as wheat or rice flour. Turmeric is sometimes added to boost health benefits of asafoetida.

I'll be sharing tincture of asafoetida at The Storytelling Secrets of Optimus Yarnspinner, a Smell & Tell program that takes place tonight at the Ann Arbor District Library (downtown branch), from 6:30-8:45pm. This unique Smell & Tell focuses on an apothecary cabinet of inspirational smells that belongs to Optimus Yarnspinner, a beloved character in the Zamonia series of books by German author Walter Moers.

Spoiler Alert: Yarnspinner uses asafoetida when he's writing horror stories. The German word for asafoetida is stinkasant. Right up there with Devil's Dung.

Developing Your Sense of Taste & Smell

As a "nose," I am often asked how one develops a vocabulary of the senses. There isn’t a simple answer to this question as describing what one smells or tastes is subjective. Every experience we have ties into another and each of us walks around with an internal compass with a particular set of reference points based on the people, places and things that have surrounded us. As each person searches for the right words, words that will add depth and meaning to their understanding, a collective tapestry of discovery is woven in which we are all inextricably linked.

This is particularly evident when an individual describes something we have encountered in a way that resonates with our personal experience of that very thing. We consider this person’s viewpoint and proceed in assessing their beliefs and notions as credible. Suspending judgment can be freeing, but it can also be a dangerous pit. When we rely solely on others to verify our perceptions, we are to a certain extent, allowing them to think and feel for us. Other people’s assessments are simply orientations. There are no absolutes in the world of the senses, which is why Proust could wax on about a single madeleine for paragraphs on end.

The perfect starting point for building an olfactive and gustatory vocabulary is observation. By paying attention to the sense of smell and taste, we begin to hone in on nuances which rely on instinct and memory, versus visual cues. In addition, the more we practice experiencing the world through taste and smell, the more skilled we become in reading people, environments and situations. This is because in doing so, we are reawakening primal skills that existed before mankind walked upright, when we could literally smell danger in food unfit for consumption or the pending arrival of a voracious animal. (One could say that modern women continue to execute this ability rather skillfully in the mating game.)

A perfect place to begin developing your sensory observation skills is the pantry. If you are a coffee lover, order a variety of regional beans in assorted roasts from a coffee shop that has relationships with growers and supports fair trade. If you are a chocolate lover, experiment with different percentages of cocoa content and regional varietals. If you are an herb or spice lover, download a free catalog from Penzy’s Spices and read it from cover to cover. Each entry in the catalog describes herbs and spices in detail and you can order in small amounts and sample flavors which befit your palate.

Should you have a touch of the mad scientist living inside you, or are particularly fond of detail, there is a link on Eblong that contains industry flavor wheels (tools which categorically organize taste families and descriptors) for beer, wine, coffee, chocolate and maple syrup. As you conduct each tasting, write down your flavor impressions and follow-up by checking them against the flavor wheel. You may want to keep a special notebook handy for your notes, so you may return to them for future comparison. Sensory experiences are deeply tied to memory and you will learn as much about yourself as the things you taste—which is why bringing a special friend along for the ride isn’t such a bad idea…

Helpful Links:

Please note that any recommendations that appear on GlassPetalSmoke are based on the editor’s tastes and preferences, which are unsolicited.
For Guittard’s single origin tasting kit, visit Chocosphere.

For coffee beans, order from The Roasterie in Kansas City.

For spices, visit a local Penzys Spices or download their catalog on the web.

For flavor wheels, visit Eblong.

Photo of perfumer Yann Vasnier courtesy of the perfumer. Vasnier was interviewed by Michelle Krell Kydd in February, for the fragrance website Bois de Jasmin. The article is entitled "Kouign Aman: The Breakfast of Perfumers." Mr. Vasnier is a native of Brittany.