How to Understand Flavor and Smell

Last week 18^th May 2024, I was lucky enough to attend a meeting of the International Society of Neurogastronomy at the University of Kentucky, here in Lexington. It sounds very formal and abstract but it’s all about flavor.

I’d been once before in 2018 when the Society was in its early days. I was flattered to be recognised by many of the participants.

Since then, research in neurogastronomy has boomed. Wow.

So What is Neurogastronomy?

I can’t do better than repeat what Tim McClintock (professor of physiology  at the University of Kentucky, known among other things for inventing as assay for odorant receptors, and current President of the Society) said in his opening remarks.

 Neurogastronomy, he said, is the study of flavor, what it is, how it works, and how to work with it.  Or how to link the science of smell and the pleasure in the evening meal.

The intellectual inspiration came from the distinguished neuroscientist Gordon Shepard who held a position at Yale for over half a century.  In 2012 he published a book titled Neurogastronomy: How the Brain Creates Flavors and Why It Matters, a term he had earlier coined in an article in Nature.

In the same year, Dan Han, who leads the neuropsychology division at the University of Kentucky Medical College fell into conversation with Fred Morin, owner-chef of Joe Beef and other acclaimed restaurants in Montreal and together they cooked up the idea of a society dedicated to neurogastronomy.  Fred describes this in the official video of the meeting.

Why does neurogastronomy matter?

The first speaker, Rachel Herz, an expert on the psychological science of smell, author of many articles and books including Why You Eat What You Eat, and a science disseminator par excellence took up that question.

We humans can smell a staggering 40 billion chemicals. Compare that to the 7 1/2 million colors and the 340,000 tones we can detect. And yet unlike vision and hearing, we as yet have no way of correcting the sense of smell if it fails.   

And fail it does as I know from personal experience. A few years ago my daughter sighed in satisfaction at the aroma of a magnolia in my garden. What aroma?  I could detect nothing.  Luckily I still have some sense of smell and am doing what I can to improve that.

How aroma affects how much we eat and what we choose to eat

Back to Rachel Herz’s presentation. She reminded the audience that we smell in two ways: the first we are all familiar with, smelling when we inhale (orthonasal olfaction, to give it the technical term); the other is less familiar, the smell when we exhale after eating or drinking and odorants reach the back of the throat (retronasal olfaction).

That led straight into some recent large-scale studies. 

For example, when people are exposed to the aromas of foods for some time before eating, pizza for example, a large proportion of those people will eat significantly less of that food.  Someone compared this to the ways chefs after working all evening in the kitchen find that they are not hungry at all. 

Also, when people entering supermarket pass through an area that smells of chocolate chip cookies warm from the oven or pizza, many of them tend to buy more ‘healthy’ foods or more fruits and vegetables.

No need to explain that results like this might have real-world potential.

Coaxing the smell-impaired (like me) to eat

Bob Pellegrino, a postdoc at the venerable Monell Chemical Senses Center at the University of Pennsylvania, talked about one part of their ambitious program Smell and Taste for Life.

Prior to COVID, 20% of people were smell impaired. That’s bad enough when compared to the 15% of people who are visually impaired with no correction.

Then 80% of COVID sufferers lost their sense of smell and of those 10% never regained it.

So Pellegrino and his colleagues are working on a Guide and Cookbook for those with impaired smell. It will offer strategies for enjoying food more:  redefining flavor as multisensory not just a matter of aromas (color, texture, sounds etc):  emphasizing the social aspect of food; and making cooking an enjoyable process.

This resonated with me because since losing so much of my sense of smell, I continue to enjoy experimenting with new recipes and I gravitate to those with interesting textures. 

Bob and I, it turned out, share a love of tendon.

Young Athletes, Grown Adults with Epilepsy, Salt, Wine, and Tasting 

Well, this is getting to be much too long a web post.  Much else was interesting too. In line with understanding different dietary needs, there was Fred Morin on coaching young hockey players in the kitchen and dining room, Monica Fowler, dietitian for the 22 University of Kentucky athletic teams (I can only imagine) on helping them eat and the problems they face, and chefs and physicians competing to prepare keto meals for those with adult epilepsy.

There were experts on salt reduction and on wine tasting. And as always, another early mover and shaker, Bob Perry, until last week chef in residence at the University of Kentucky, offered a series of tables with tasting samples to illustrate what was being discussed. All very hands on.

Neurogastronomy as a rapidly evolving field of study

As we broke up for coffee, I asked the person next to me whether I was right that neurogastronomy had advanced by leaps and bounds since I had last encountered it six years ago.

She turned out to be Nancy Rawson, cell biologist and senior scientist at the Monell Center.  I couldn’t have picked a better person.

Oh yes, was her answer. 

Partly certain important technologies necessary for research have been perfected. Partly COVID meant increased funding. The Global Consortium for Chemosensory Research has grown to over 700 members in 70 or so different countries.

What a great day. Close to my research area but information new to me. Small with lots of time to talk over breaks and meals. Simultaneously intellectually rigorous and with practical implications. Multidisciplanary with neurologists, chemists, physicians, dietitians, sommeliers, chefs, and more. Hands on meals and tastings. So much fun.

Should you want to learn more

1. Try the jelly bean test.  Hold your nose, put the jelly bean in your mouth, taste just the sweet, now release your nose, and you will be able to detect the flavor using retronasal olfaction. (This doesn’t work for me, sad to say).
2. The societies and institutions mentioned have mailing lists. Sign up if you are interested.
3. Read the books by Gordon Sheppard and Rachel Herz (links in text) or listen to Rachel’s most recent Ted Talk
4. I was going to suggest that if you have lost your sense of smell, you might find AbScent useful.  I see though that it going through significant changes which are indicated on its website.

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