Digital aromas? And a potpourri of ‘scents and sensibility’

Mmm… smelly books. Illustration by Dorothy Woodend.[downloaded from]

I don’t get to post about scent as often as I would like, although I have some pretty interesting items here, those links to follow towards of this post).

Digital aromas

This Nov. 11, 2020 Weizmann Institute of Science press release (also on EurekAlert published on Nov. 19, 2020) from Israel gladdened me,

Fragrances – promising mystery, intrigue and forbidden thrills – are blended by master perfumers, their recipes kept secret. In a new study on the sense of smell, Weizmann Institute of Science researchers have managed to strip much of the mystery from even complex blends of odorants, not by uncovering their secret ingredients, but by recording and mapping how they are perceived. The scientists can now predict how any complex odorant will smell from its molecular structure alone. This study may not only revolutionize the closed world of perfumery, but eventually lead to the ability to digitize and reproduce smells on command. The proposed framework for odors, created by neurobiologists, computer scientists, and a master-perfumer, and funded by a European initiative [NanoSmell] for Future Emerging Technologies (FET-OPEN), was published in Nature.

“The challenge of plotting smells in an organized and logical manner was first proposed by Alexander Graham Bell [emphasis mine] over 100 years ago,” says Prof. Noam Sobel of the Institute’s Neurobiology Department. Bell threw down the gauntlet: “We have very many different kinds of smells, all the way from the odor of violets [emphasis mine] and roses up to asafoetida. But until you can measure their likenesses and differences you can have no science of odor.” This challenge had remained unresolved until now.

This century-old challenge indeed highlighted the difficulty in fitting odors into a logical system: There are millions of odor receptors in our noses, consisting hundreds of different subtypes, each shaped to detect particular molecular features. Our brains potentially perceive millions of smells in which these single molecules are mixed and blended at varying intensities. Thus, mapping this information has been a challenge. But Sobel and his colleagues, led by graduate student Aharon Ravia and Dr. Kobi Snitz, found there is an underlying order to odors. They reached this conclusion by adopting Bell’s concept – namely to describe not the smells themselves, but rather the relationships between smells as they are perceived.

In a series of experiments, the team presented volunteer participants with pairs of smells and asked them to rate these smells on how similar the two seemed to one another, ranking the pairs on a similarity scale ranging from “identical” to “extremely different.” In the initial experiment, the team created 14 aromatic blends, each made of about 10 molecular components, and presented them two at a time to nearly 200 volunteers, so that by the end of the experiment each volunteer had evaluated 95 pairs.

To translate the resulting database of thousands of reported perceptual similarity ratings into a useful layout, the team refined a physicochemical measure they had previously developed. In this calculation, each odorant is represented by a single vector that combines 21 physical measures (polarity, molecular weight, etc.). To compare two odorants, each represented by a vector, the angle between the vectors is taken to reflect the perceptual similarity between them. A pair of odorants with a low angle distance between them are predicted similar, those with high angle distance between them are predicted different.

To test this model, the team first applied it to data collected by others, primarily a large study in odor discrimination by Bushdid [C. Bushdid] and colleagues from the lab of Prof. Leslie Vosshall at the Rockefeller Institute in New York. The Weizmann team found that their model and measurements accurately predicted the Bushdid results: Odorants with low angle distance between them were hard to discriminate; odors with high angle distance between them were easy to discriminate. Encouraged by the model accurately predicting data collected by others, the team continued to test for themselves.

The team concocted new scents and invited a fresh group of volunteers to smell them, again using their method to predict how this set of participants would rate the pairs – at first 14 new blends and then, in the next experiment, 100 blends. The model performed exceptionally well. In fact, the results were in the same ballpark as those for color perception – sensory information that is grounded in well-defined parameters. This was especially surprising considering each individual likely has a unique complement of smell receptor subtypes, which can vary by as much as 30% across individuals.

Because the “smell map,” [emphasis mine] or “metric” predicts the similarity of any two odorants, it can also be used to predict how an odorant will ultimately smell. For example, any novel odorant that is within 0.05 radians or less from banana will smell exactly like banana. As the novel odorant gains distance from banana, it will smell banana-ish, and beyond a certain distance, it will stop resembling banana.

The team is now developing a web-based tool. This set of tools not only predicts how a novel odorant will smell, but can also synthesize odorants by design. For example, one can take any perfume with a known set of ingredients, and using the map and metric, generate a new perfume with no components in common with the original perfume, but with exactly the same smell. Such creations in color vision, namely non-overlapping spectral compositions that generate the same perceived color, are called color metamers, and here the team generated olfactory metamers.

The study’s findings are a significant step toward realizing a vision of Prof. David Harel of the Computer and Applied Mathematics Department, who also serves as Vice President of the Israel Academy of Sciences and Humanities and who was a co-author of the study: Enabling computers to digitize and reproduce smells. In addition, of course, to being able to add realistic flower or sea aromas to your vacation pictures on social media, giving computers the ability to interpret odors in the way that humans do could have an impact on environmental monitoring and the biomedical and food industries, to name a few. Still, master perfumer Christophe Laudamiel, who is also a co-author of the study, remarks that he is not concerned for his profession just yet.

Sobel concludes: “100 years ago, Alexander Graham Bell posed a challenge. We have now answered it: The distance between rose and violet is 0.202 radians (they are remotely similar), the distance between violet and asafoetida is 0.5 radians (they are very different), and the difference between rose and asafoetida is 0.565 radians (they are even more different). We have converted odor percepts into numbers, and this should indeed advance the science of odor.”

I emphasized Alexander Graham Bell and the ‘smell map’ because I thought they were interesting and violets because they will be mentioned again later in this post.

Meanwhile, here’s a link to and a citation for the paper (the proposed framework for odors),

A measure of smell enables the creation of olfactory metamers by Aharon Ravia, Kobi Snitz, Danielle Honigstein, Maya Finkel, Rotem Zirler, Ofer Perl, Lavi Secundo, Christophe Laudamiel, David Harel & Noam Sobel. Nature volume 588, pages 118–123 (2020) DOI: Published online: 11 November 2020 Journal Issue Date: 03 December 2020

This paper is behind a paywall.

Smelling like an old book

Some folks are missing the smell of bookstores and according to Dorothy Woodend’s Nov. 19, 2020 article for The Tyee, that longing has resulted in a perfume (Note: Links have been removed),

The news that Powell’s Books, Portland’s (Oregon, US) beloved bookstore, had released a signature scent was greeted with bemusement by some, confusion by others. But to me it made perfect scents. (Err, sense.) If you love something, I mean really love it, you love the way it smells.

Old books have a distinctive peppery aroma that draws bibliophiles like bears to honey. Some people are very specific about their book smells, preferring vintage Penguin paperbacks from the mid to late 1960s. Those orange spines aged like fine wine.

Powell’s created the scent after people complained about missing the smell of the store during lockdown. It got me thinking about how identity is often bound up with smell and, more widely, how smells belong to cultural, even historic moments.

Olfactory obsolescence can have weird side effects … . Memories of one’s grandfather smelling like pipe tobacco are pretty much now only a literary conceit. But pipe smoke isn’t the only dinosaur smell that is going extinct. Even in my lifetime, I remember the particular aroma of baseball cards and chalk dust.

Remember violets? Here’s more about Powell’s Unisex Fragrance (from Powell’s purchase webpage),

• Wood
• Violet
• Biblichor

Like the crimson rhododendrons in Rebecca, the heady fragrance of old paper creates an atmosphere ripe with mood and possibility. Invoking a labyrinth of books; secret libraries; ancient scrolls; and cognac swilled by philosopher-kings, Powell’s by Powell’s delivers the wearer to a place of wonder, discovery, and magic heretofore only known in literature.

How to wear:
This scent contains the lives of countless heroes and heroines. Apply to the pulse points when seeking sensory succor or a brush with immortality.

• 1 ounce
• Glass bottle
• Limited-edition item available while supplies last

Shipping details:
Powell’s Unisex Fragrance ships separately and only in the contiguous United States [emphasis mine]. Special shipping rates apply.

Links: oPhone and heritage smells

Some years I was quite intrigued by the oPhone (scent by telephone) and wrote these: For the smell of it, a Feb. 14, 2014 posting, and Smelling Paris in New York (update on the oPhone), a June 18, 2014 posting. I haven’t found any updates about oPhone in my brief searches on the web.

There was a previous NANOSMELL (sigh, these projects have various approaches to capitalization) posting: Scented video games: a nanotechnology project in Europe published here in a May 27, 2016 posting.

More recently on the smell front, there was this May 22, 2017 posting, Preserving heritage smells (scents). FYI, the authors of the 2017 paper are part of the Odeuropa project described in the next subsection.

Context: NanoSmell and Odeuropa

Science funding is intimately linked to science policy. Examination of science funding can be useful for understanding some of the contrasts between how science is conducted in different jurisdictions, e.g., Europe and Canada.

Before launching into the two ‘scent’ projects, NanoSmell and Odeuropa, I’m offering a brief description of one of the European Union’s (EU) most comprehensive and substantive (many, many Euros) science funding initiatives.The latest iteration of this initiative has funded and is funding both NanoSmell and Odeuropa.

Horizon Europe

The initiative has gone under different names: Framework Programmes 1-7, then in 2014, it was called Horizon 2020 with its end date part of its name. The latest initiative, Horizon Europe is destined to start in 2021 and end in 2027.

The most recent Horizon Europe budget information I’ve been able to find is in this Nov. 10, 2020 article by Éanna Kelly and Goda Naujokaitytė for,

EU governments and the European Parliament on Tuesday [Nov. 10, 2020] afternoon announced an extra €4 billion will be added to the EU’s 2021-2027 research budget, following one-and-a-half days of intense negotiations in Brussels.

The deal, which still requires a final nod from parliament and member states, puts Brussels closer to implementing its gigantic €1.8 trillion budget and COVID-19 recovery package. [emphasis mine]

In all, a series of EU programmes gained an additional €15 billion. Among them, the student exchange programme Erasmus+ went up by €2.2 billion, health spending in EU4Health by €3.4 billion, and the InvestEU programme got an additional €1 billion.

Parliamentarians have been fighting to reverse cuts [emphasis mine] made to science and other investment programmes since July [2020], when EU leaders settled on €80.9 billion (at 2018 prices) for Horizon Europe, significantly less than €94.4 billion proposed by the European Commission.

“I am really proud that we fought – all six of us as a team,” said van Overtveldt [Johan Van Overtveldt, Belgian MEP {member of European Parliament} on the budget committee], pointing to the other budget MEPs who headed talks with the German Presidency of the Council. “You can take the term ‘fight’ literally. We had to fight for what we got.”

“We are all very proud of what we achieved, not for the parliament’s pride but in the interest of European citizens short-term and long-term,” van Overveldt said.

One of the most visible campaigners for science in the Parliament, MEP Christian Ehler, spokesman on Horizon Europe for the European Peoples’ Party, called the deal “a victory for researchers, scientists and citizens alike.” [emphasis mine]

The challenge now for negotiators will be to figure out how to divide extra funds [emphasis mine] within Horizon Europe fairly, with officials attached to public-private partnerships, the European Research Council, the new research missions, and the European Innovation Council all baying for more cash.

To sum up, in July 2020, legislators settled on the figure of €80.9 billion for science funding over the seven year period of 2021 – 2027 to administered by Horizon Europe. After fighting €4 billion was added for a total of €84.9 billion in research funding over the next seven years.

This is fascinating to me; I don’t recall ever seeing any mention of Canadian legislators arguing over how much money should be allocated to research in articles about the Canadian budget. The usual approach is treat the announcement as a fait accompli and a matter for celebration or intense criticism.

Smell of money?

All this talk of budgets and heritage smells has me thinking about the ‘smell of money’. What happens as money or currency becomes virtual rather than actual? And, what happened to the smell of Canadian money which is now made of plastic?

I haven’t found any answers to those questions but I did find an interesting June 14, 2012 article by Sarah Gardner for titled, Sniffing out what money smells like. The focus is on money made of cotton and linen. One other note, this is not the Canadian Broadcasting Corporation’s Marketplace television programme. This is a US programme from American Public Media (from the FAQs webpage).

Now onto the funding for European smell research.


The Israeli researchers’ work was funded by Horizon 2020’s NanoSmell project which ran from Sept. 1, 2015 – August 31, 2019 and this was their objective (from the CORDIS NanoSmell project page),

“Despite years of promise, an odor-emitting component in devices such as televisions, phones, computers and more has yet to be developed. Two major obstacles in the way of such development are poor understanding of the olfactory code (the link between odorant structure, neural activity, and odor perception), and technical inability to emit odors in a reversible manner. Here we propose a novel multidisciplinary path to solving this basic scientific question (the code), and in doing so generate a solution to the technical limitation (controlled odor emission). The Bachelet lab will design DNA strands that assume a 3D structure that will specifically bind to a single type of olfactory receptor and induce signal transduction. These DNA-based “”artificial odorants”” will be tagged with a nanoparticle that changes their conformation in response to an external electromagnetic field. Thus, we will have in hand an artificial odorant that is remotely switchable. The Hansson lab will use tissue culture cells expressing insect olfactory receptors, functional imaging, and behavioral tests to validate the function and selectivity of these switchable odorants in insects. The Carleton lab will use imaging in order to investigate the patterns of neural activity induced by these artificial odorants in rodents. The Sobel lab will apply these artificial odorants to the human olfactory system, [emphasis mine] and measure perception and neural activity following switching the artificial smell on and off. Finally, given a potential role for olfactory receptors in skin, the Del Rio lab will test the efficacy of these artificial odorants in promoting wound healing. At the basic science level, this approach may allow solving the combinatorial code of olfaction. At the technology level, beyond novel pharmacology, we will provide proof-of-concept for countless novel applications ranging from insect pest-control to odor-controlled environments and odor-emitting devices such as televisions, phones, and computers.” [emphasis mine]

Unfortunately, I can’t find anything on the NanoSmell Project Results page with links to any proof-of-concept publications or pilot projects for the applications mentioned. Mind you, I wouldn’t have recognized the Israeli team’s A measure of smell enables the creation of olfactory metamers as a ‘smell map’.


Remember the ‘heritage smells’ 2017 posting? The research paper listed there has two authors, both of whom form one of the groups (University College London; scroll down) associated with Odeuropa’s Horizon 2020 project announced in a Nov. 17, 2020 posting by the project lead, Inger Leemans on the Odeuropa website (Note: A link has been removed),

The Odeuropa consortium is very proud to announce that it has been awarded a €2.8M grant from the EU Horizon 2020 programme for the project, “ODEUROPA: Negotiating Olfactory and Sensory Experiences in Cultural Heritage Practice and Research”.Smell is an urgent topic which is fast gaining attention in different communities. Amongst the questions the Odeuropa project will focus on are: what are the key scents, fragrant spaces, and olfactory practices that have shaped our cultures? How can we extract sensory data from large-scale digital text and image collections? How can we represent smell in all its facets in a database? How should we safeguard our olfactory heritage? And — why should we? …

The project bundles an array of academic expertise from across many disciplines—history, art history, computational linguistics, computer vision, semantic web, museology, heritage science, and chemistry, with further expertise from cultural heritage institutes, intangible heritage organisations, policy makers, and the creative and fragrance industries.

I’m glad to see this interest in scent, heritage, communication, and more. Perhaps one day we’ll see similar interest here in Canada. Subtle does not mean unimportant, eh?

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