Science Friday - Science Unlocks The Power Of Flavor In ‘Flavorama’

Episode Date: March 19, 2024

Think about the best meal you’ve ever eaten: Maybe it was in a restaurant in a far-off city, or perhaps it was a home-cooked meal made by someone you love. No matter where or what it was, odds are what made it so memorable was the flavor.Flavor is arguably the most important part of a meal. If the flavor of something is off, or undetectable, it can jeopardize your enjoyment. There’s a lot of chemistry and biological science behind how and what we taste.Flavorama: A Guide to Unlocking the Art and Science of Flavor is a new book that breaks down the mechanisms that go into these processes. Ira is joined by author Arielle Johnson, who holds a PhD in chemistry and co-founded the fermentation lab at the world-famous Copenhagen restaurant Noma.Transcripts for each segment will be available the week after the show airs on sciencefriday.com Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

There's a lot of chemistry that goes into how and what we taste. There's some aroma compounds in bell peppers and sulfur compounds and wine and garlic that we're almost ridiculously sensitive to. It's Tuesday, March 19th, and would you look at that? Today is Science Friday. I'm SciFri producer Kathleen Davis. Flavor is arguably the most important part of a meal. If the flavor of something is off or undetectable, it can jeopardize your enjoyment. There's so much science that goes on behind our sense of taste.

Flavor scientist Ariel Johnson knows all about this, and she wrote a book, Flavorama, unlocking the art and science of flavor. She joins Ira Flato to talk about it. You're quite a resume. I mean, you have a PhD in flavor chemistry. You've worked at some of the best restaurants in the world, including Noma in Copenhagen, that is something. How did you get interested in the chemistry behind flavor? Well, I was I was always like pretty interested in in science generally and, you know, pretty interested in food and I guess eventually, well, I was in high school, Faran Adria, the chef at Elbe, which was like a super influential experimental Spanish restaurant. So he was on the cover of the New York Times magazine and he was like holding

this like little container of like carrot foam. And, um, I was like, what is that? And it was a whole article about how, like, they were using, you know, a sort of scientific understanding of food to make insane novel completely out there cuisine. And I was like, oh, clearly that's what I need to be doing. Yeah, well, that's what I want to get into. You being a chemist and a flavor specialist, I want to ask you the chemistry behind flavor. When we taste something in our mouths, what's the chemistry that's going?

on in there? Well, so flavor is a mix of mostly taste and smell. The other senses feed into it, but if you're thinking about like the main players here, it's taste and smell. And the flavored part of anything you eat is really like a tiny, tiny component of it, less than maybe 5%. In the case of smell, it can be like one part per million. So there's, yeah, there's molecules and food that we have either taste or smell receptors for. And those molecules, you know, eventually find those receptors that are shaped sort of like a special catchers mitt, a lot of them, grab onto the molecules and then send a signal to the brain, which, you know, sort of knits it all together to create our perception of flavor.

Speaking of flavor, then, are there some flavor molecules that are easier for us to taste than others or hit our tongues faster than others? I think we're probably, in terms of taste, most sensitive to bitter compounds, just because we have our sense of bitter taste to protect us from potentially toxic materials. And since toxic things can be toxic in very small quantities, I think generally our most acute taste is for bitter. When you get into smell, there's some aroma compounds in bell peppers and sulfur compounds and wine and garlic that we're almost ridiculous. sensitive to. They're actually, while I was in grad school, some of my colleagues were working on methods to actually measure these things quantitatively, because our nose was more sensitive than our chemical instruments were. So there were materials that were in such tiny concentrations that you

could absolutely smell and taste them, but would not show up at all on your gas chromatographed mass spectrometer. So, yeah, very, very sensitive. Especially wine tasters. You know, they'll say things about wine that you have no idea what you're talking about. But they do. So that's what's important, I guess, right? Yeah, yeah. Well, I mean, I think the sort of second component to a lot of my research was doing sensory

analysis, which is basically like very careful tasting. So I actually trained a lot of people to get good at describing the flavors that they were tasting. Now, speaking of flavors, I remember when we were all kids learning about the, the body parts. We're seeing a map of our taste buds and had certain sections dedicated to certain tastes. But is it true? It turns out that's not exactly right about our taste buds?

Yeah, we've pretty much got all five kinds of taste buds all over our tongue. You know, more on like the front and the sides in the back, but there isn't really a special region just for bitter or umami or sour. Wow. That's a fairly persistent myth, unfortunately. Wow. Now, if you go to the grocery store, you see there are many different types of salt, and I use salt a lot in cooking and making bread and stuff. There's sea salt.

There's a pink Himalayan salt. There are more expensive salts than others. Are there really various types of salt that are chemically different? Well, so all salt is sodium chloride. So in that sense, all salts are the same. Yeah, but, you know, there's also small amounts of impurities. So those are the things that make, you know, Himalayan salts pink and things like that. And there is research that has found that when you dissolve sort of specialty salts in water,

so to like remove any effects of texture, because they're all dissolved, you can actually taste differences between them. So these sort of trace minerals and other quote unquote impurities are contributing something to the flavor of the salt. It's minor, but it's definitely there. Wow. You know, you were talking about how important it is that you use your nose when you're tasting something because your nose and your taste buds are working together. How does that actually happen?

Is there a pathway? Yes. How do they coordinate? There is a pathway. When one says, when one hears, that smell is an important part of flavor, most people hear smell and think like sniffing. So like, oh, when the food is in front of my face, I'm sniffing it, and that smell is part of flavor. And that's a small part of flavor.

But once you have food in your mouth, the smell molecules in it will travel up the back of your throat and through the back of your nasal cavity and then attach to your olfactory receptors there. So it's a special kind of smell. We call it retronasal olfaction, or a sniffing would be orthonasal olfaction. Yeah. So that's why when you have a cold, it never makes that journey from the back up to your nose because your nose is stuffed. Exactly. Yeah. And that's, I think, one of the best ways to get people to understand that smell is a part of flavor is, you know, when if you have a cold and everything tastes flat or like, oh, the flavor.

Flavor is very muted. That's flavor minus smell. So that's taste on its own. I didn't know that. Wow, that is good to know. I also didn't know until reading your book that we have 400 types of smell receptors. Yeah, approximately 400 different types of smell receptors. Each one has their own gene, and that family of genes, it's actually a super family of genes,

is the largest group in our genome. So you have like one for smokiness, another for sweetness in our noses? Yeah, I mean, smell is a little weird compared to. to taste. So, you know, taste you have, it's almost like pressing a piano key and you get like one note from that. So you press the C key, you get C. Activate, put salt on the salt receptor. It tastes salty. With smell, we've kind of developed a more flexible system. So it's a little less like pressing a piano key and a little bit more like reading a barcode. So each of our 400 receptors will like bind to different degrees with many different smell molecules. molecules and any small molecule will bind with several different receptors. So you generate essentially like a two-dimensional QR code. That's the pattern that gets created on your old factory bulb. And then that gets sent to your sort of emotional and memory and eventually

cognitive parts of your brain. A big focus in your book and in your work you do is fermentation. Now, I do fermentation in my kitchen and, you know, from my sourdough bread to some vegetables. What is it about fermentation that makes it such a driver of flavor? Well, so when you do fermentation, you're essentially transforming ingredients with microbes. So the microbes might be yeast. They might be lactic acid bacteria. They could be certain molds or acetic bacteria.

But basically, you're giving these microbes a nice environment to live in and the food that they like to eat. and in exchange they'll consume that thing and then produce byproducts essentially that happen to have a lot of flavor. So with lactic acid bacteria, the biggest one is lactic acid, which is nice and tangy. So that's why, you know, sauerkraut tastes so different from raw cabbage. But there are also a lot of minor metabolites, we call them, because it's a product of the metabolism, that, you know, add to the aroma of ingredients. So we love fermentation because it makes more flavors. Well, you know, when I open my jar of starter as it's getting ready and it's blooming,

it smells so wonderful. Yeah, yeah. It's amazing what that smells like. Now, flavor is largely a personal preference, right? I mean, some people love sweet things, others don't. Same goes for sour or spicy. So how do you, as a chef, graph, with this, making something unique and flavorful.

I mean, do you take those differences of people in mind? Or you just say, I want it this way, and I don't really care what the public thinks about, most people care. Well, I mean, I think you want people to have a good time, otherwise you wouldn't be in hospitality. That makes sense. But I think when we're doing a new dish, so not just like a version of an existing dish, but some kind of totally new dish, generally what?

makes it successful is if some part of it is novel and not seen before, but there is some familiarity there, whether that's in, you know, format or flavors or something. So as long as people are willing to be like a little bit adventurous, generally if you give them something that's a little bit familiar and a little bit novel, they will have a good time. That's interesting. Does sight, when you look at food, does it influence how you think it might taste and what the flavor might be? Yeah? Tell me about that. Absolutely. So if you think of flavor as a sort of tool that humans as an organism use,

it's, you know, to figure out what to feed ourselves, to get good things and not get bad things. So, like, of course, you'd use as much information as possible to get that, you know, fully fleshed out picture of whether something's good and what it's going to taste like. So, yeah, vision is a big one for setting expectations. There's a classic sensory science experiment where when you add green dye to orange juice and give it to a taste panel, they will generally think that it tastes like limey instead of orange juice just from the color. Right, right. So they get the signal of like, oh, citrusy and sour and sweets.

It's something, but it's green, got to be limey. Right. I once did a TV show, a science TV show, where we took a scoop of mashed potatoes and potatoes, and put it on an ice cream cone. Oh, man. And boy, the faces people thought when they thought it was going to be vanilla ice cream. They had no idea what they were eating. It took quite a while for them to figure this out.

Yeah, no, expectations and context are like huge for being able to understand what you're eating. So, yeah, I'm sure. I'm sure they were big fans of you after that. Let me remind everybody that this is Science Friday from WNYC Studios. Okay. So you're just joining us. we're talking about flavor with Ariel Johnson, author of Flavorama. All right, tell me some tips.

A beginner can take advantage of harnessing the power of flavor in our cooking. Yeah, well, so there's lots of different ways. You know, since flavor is a perceptual and psychological phenomenon, sometimes that's the most important thing happening in a flavor situation. A lot of cooking techniques are about sort of selectively moving flavor molecules around. I know that sounds very abstract, but essentially brewing a cup of coffee or making chicken stock are both that moving flavor molecules into water. And then there's lots of cooking techniques we're actually doing chemical reactions. So smoking, caramelizing, and browning are big ones.

And fermentation is huge for reacting molecules. So taking a step back, some simple things. So if you have food that's too bitter, there are actually some tricks that you can do. to make it taste less bitter without actually removing bitterness. The big one is to add salt. So if you have any kind of like a salty dog cocktail, which has grapefruit juice, or in fact,

some people like to put salt on their grapefruit, the salt will actually like interfere with your perception of bitterness and reduce how bitter the thing tastes to a, you know, statistically significant degree. No, yeah. Okay. You know, acid and sweet are also good on that, but salt is particularly good.

a lot of people love browned food. We love coffee, we love chocolate, we love toast, roasted chicken, roast beef, dark pretzs, barbecue. Yeah, so all of that comes from one reaction or sort of family of reactions called the Mayard reaction. It is the reaction that creates brown color and, you know, sort of toasty brown flavors. That's a reaction between amino acids and sugars. So if you want more browning, you can think about adding more sugar, obviously, you know, that's people, people do that to add caramel color. Right. But if you can, you know, increase the amount of protein and amino acids you have, you'll get, like, much more browning.

It's also very sensitive to pH, to acidity and alkalinity. You get more browning under alkaline conditions and less browning under acidic conditions. So if it's going to brown, you can add some acidity. If you want as much brown as possible, you can add, for example, a little baking soda. And that has to do with actually whether the amino end of the amino acid is protonated. Not that you have to think about that as a cook. But it's weird where these things will eventually take you when you look into their mechanisms. You know, last question and observation about your book.

When I opened it immediately, it is a fun book. I mean, I thought it was a kid's book when I first opened with all the pastel colors and the wonderful drawings. Thank you. What made you decide to do it that way? Well, so I actually illustrated it as well, and I've done a lot of sort of illustrating of, you know, talks and things that I write. Just because I feel, you know, the point of like writing something or talking to someone is communication, you know, and getting a point. or a message or helpful stuff across. So to me, I think there's certainly as an academic myself,

there's a strong pressure to like take a very serious tone. But you don't have to. And it's actually like more fun to read if you don't. And, you know, I want I want people to understand. It is. Pictures help with that. It is beautifully, beautifully illustrated, beautifully written. And a joy to read, Ariel.

Thank you for the book and for taking time to be with us today. It was a great conversation. Thank you for having me. You're welcome. Ariel Johnson, author of Flavorama, unlocking the art and science of flavor. She's based in New York. And if you want to read an excerpt from the book, yeah, this is a great book. You can go to our website, ScienceFriday.com slash Flavorama. And that's all the time that we have for today. A lot of folks help make the show happen, including Ariel Zich, Santiago Flores, Emma Gomez, Diana Plasker, and many more.

tomorrow we'll step into the time machine. It's been four years since the WHO declared COVID-19 a pandemic. Can you believe it? That's next time. But for now, I'm CyFRI producer Kathleen Davis. Have a good one.