Sweet, Sour, Salty, Bitter ... and Umami



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An illustration of taste buds from Gray's Anatomy of the Human Body.  When taste buds were discovered in the 19th century, tongue cells under a microscope looked like little keyholes into which bits of food might fit, and the idea persisted that there were four different keyhole shapes.
An illustration of taste buds from Gray's Anatomy of the Human Body. When taste buds were discovered in the 19th century, tongue cells under a microscope looked like little keyholes into which bits of food might fit, and the idea persisted that there were four different keyhole shapes.

So here's a question you don't hear every day: How many tastes can a person taste?

There's sweet, of course. Then sour. Then salty. And when the Greek philosopher Democritus took up the question several thousand years ago, he added bitter. So that makes four.

Democritus said (not because he did any experiments; being a philosopher, he thought for a living) that when you chew on your food and it crumbles into little bits, those bits eventually break into four basic shapes.

When something tastes sweet, he said, it is because the bits are "round and large in their atoms." Salty is isosceles triangle bits on your tongue, Bitter is "spherical, smooth, scalene and small," while sour is "large in its atoms, but rough, angular and not spherical."

And that's it, said Democritus. Everything we taste is some combination of those four ingredients.

And that made sense to Plato, and made sense to Aristotle, and pretty much ever since even modern scientists have said that's the number: four.

When taste buds were discovered in the 19th century, tongue cells under a microscope looked like little keyholes into which bits of food might fit, and the idea persisted that there were four different keyhole shapes.

So four it is. Four it was.

And then, along came Auguste Escoffier.

What the Chef Tasted

Escoffier was a chef. Not just a chef, in Paris in the late 1800s he was the chef. He had opened the most glamorous, most expensive, most revolutionary restaurant in the city. He had written a cookbook, The Guide Culinaire. And, says science writer Jonah Lehrer (a colleague of mine on NPR/WNYC's Radio Lab), he also created meals that tasted like no combination of salty, sour, sweet and bitter; they tasted new. Escoffier invented veal stock.

And should you choose to listen to our broadcast on Morning Edition, you will hear Jonah and me "cooking" (the sounds were snatched from sound effects records, but I think you will drool anyway) what was then considered a spectacularly new sauce that seemed to deepen and enrich the flavor of everything it touched.

"It didn't just taste good," Jonah says. "This was an epiphany. This was the best food you ever tasted in your life."

But because it was neither sweet, bitter, sour, salty nor any combination of those four, as far as the scientists were concerned, it wasn't real. People may smack their lips, drool, savor and pay enormous amounts of money to M. Escoffier, but what they were tasting wasn't really there. It was all in their heads.

What the Japanese Soup Lover Tasted

Meanwhile, halfway across the world, a chemist named Kikunae Ikeda was at the very same time enjoying a bowl of dashi, a classic Japanese soup made from seaweed. He too sensed that he was tasting something beyond category. Dashi has been used by Japanese cooks much the way Escoffier used stock, as a base for all kinds of foods. And it was, thought Ikeda, simply delicious.

But what was it? Being a chemist, Ikeda could find out. He knew what he was tasting was, as he wrote, "common to asparagus, tomatoes, cheese and meat but… not one of the four well-known tastes." Ikeda went into his lab and found the secret ingredient. He wrote in a journal for the Chemical Society of Tokyo that it was glutamic acid, but he decided to rename it. He called it "umami," which means "delicious" or "yummy" in Japanese.


Glutamate is found in most living things, but when they die, when organic matter breaks down, the glutamate molecule breaks apart. This can happen on a stove when you cook meat, over time when you age a parmesan cheese, by fermentation as in soy sauce or under the sun as a tomato ripens. When glutamate becomes L-glutamate, that's when things get "delicious." L-glutamate, said Ikeda, is a fifth taste. When Escoffier created veal stock, he was concentrating umami. When Japanese made their dashi, they were doing the same thing. When you bite into an anchovy, they are "like glutamate speedballs. They are pure umami," Jonah writes. "Aristotle was wrong. Plato was wrong. We have five tastes, not four. But when Ikeda's findings were published," Jonah says, "nobody believes him."

So Who Was Right?

It turns out, almost 100 years after Escoffier wrote his cookbook and Ikeda wrote his article, a new generation of scientists took a closer look at the human tongue and discovered, just as those two had insisted, that yes, there is a fifth taste. Humans do have receptors for L-glutamate and when something is really, really yummy in a non-sweet, sour, bitter or salty way, that's what you're tasting. In 2002, this became the new view. It's in the textbooks now and scientists decided to call this "new" taste, in Ikeda's honor, "umami." If you want to get an umami headache, add some monosodium glutamate to your next bowl of noodles.

The Moral

In his new book, Proust Was a Neuroscientist, Jonah tells eight stories that share a common theme. In each case, (he chooses Marcel Proust, Walt Whitman, George Elliot, Paul Cezanne, Igor Stravinsky, Gertrude Stein, Virginia Wolf and, yes Auguste Escoffier) an artist is busy about his/her work and happens to observe something or sense something about the real world that scientists have not yet noticed, or that scientists say is not true. But because artists are so good at describing what it's like to experience the world, so intent on delivering the truth of what it feels like to be alive, so intuitive, in each of these eight cases, the artists learn something that the scientists don't discover until years later.

Art, Jonah reminds us, describes the same world that science does; art just does it by a different route. And sometimes, more often than you would suppose, the artists get there first.

Copyright 2016 NPR. To see more, visit http://www.npr.org/.

Copyright NPR. View this article on npr.org.



This next story is about a forbidden taste. You and I think we can taste this taste, but for more than 2,000 years scientists have said no, we can't. So who's right?

NPR's Robert Krulwich has the story.

ROBERT KRULWICH: Twenty-four hundred years ago, the Greek philosopher Democritus asked himself why do some things taste sweet and some things salty. And he decided maybe it has to do with shape. So when you eat, say, in our case…

(Soundbite of chewing)

KRULWICH: …a salty potato chips and you chew and it breaks down into very teeny bits in your mouth, some of those bits, Democritus imagined, might be shaped like isosceles triangles.

(Soundbite of swallowing)

KRULWICH: So that's what salty is, he thought, little triangles on your tongue. Sweet is round bits on your tongue. And then there's another shape for bitter; another for sour. So there are four shapes, said Democritus, and four tastes.

JONAH LEHRER: Yes, there were four basic tastes.

KRULWICH: Again, that's sweet and salt.

LEHRER: Let's see: sour, salty, sweet, bitter.

KRULWICH: Uh-huh. Sour, salty, sweet and bitter. And, says science writer Jonah Lehrer, that became the orthodox view.

LEHRER: This wasn't even the orthodox's view. This was the view.

KRULWICH: Plato said, I agree the tongue has four tastes. Then Aristotle said, me, too. And then everybody said, yep. And ever since, even modern scientists have stuck with that formula.

So for more than 2,000 years, the scientific establishment says if it isn't sweet or sour or bitter or salty, you can't taste it. It ain't there.

And then along came Auguste Escoffier.

(Soundbite of music)

LEHRER: He was a French chef who worked in the Hotel Ritz.

KRULWICH: Oh. The hotel. So we're going to go to Paris in the 18-, what, something…

LEHRER: 18th century, early 20th century.

KRULWICH: Oh, a very sort of Moulin Rouge kind of thing.

LEHRER: Yes. Yes, exactly.

KRULWICH: And when Chef Escoffier opened the most famous restaurant ever in France, he created a taste that was not SSS or B - sour, salty, sweet or bitter.

Okay. So now through the magic of radio, you and I, Jonah, we are going to create Escoffier's recipe for veal stock. So if you follow me here into my imaginary kitchen, I'm going to fry - what am I going to fry?

LEHRER: You put on a little pork rind, a little carrot, some meat scraps.

KRULWICH: Okay. Wait, wait. Pork rind…

(Soundbite of frying)

KRULWICH: Carrots.

LEHRER: And you fry the meat, let it burn a little bit.


LEHRER: You're going to get the sizzle. You can hear the crust forming on the meat.

KRULWICH: Now, the recipe says you wait for a crackle. Is that right?

LEHRER: Yes. Yes. Listen to the sound of crackling.


(Soundbite of crackling)

KRULWICH: Perfect crackle. So now, I'm going to take some - and add cold water. No?

LEHRER: Exactly, exactly.

KRULWICH: And I'm going to take some veal bones I've been roasting in the oven. I pop them in.

LEHRER: And you boil, boil, boil.


LEHRER: Simmer, simmer, simmer.

KRULWICH: How long do I simmer for, would you say?

LEHRER: About 12 hours.

KRULWICH: Twelve hours.

(Soundbite of laughter)

KRULWICH: And I was supposed to do this again. It says more bones and more simmer until, finally, I get this rich, concentrated sauce.

LEHRER: But it smells like the essence of veal. You know, it's got 20 hours of meat juice in it.

KRULWICH: So now, after, what, 24 hours probably, now we're ready to have - to begin cooking.

LEHRER: It's been a long day, yes. Now you're ready to start cooking.

KRULWICH: So now, someone in the restaurant is going to order.

Unidentified Man #1: (French spoken)

Unidentified Man #2: Tres bien.

KRULWICH: All right now. Escoffier can cook a steak and then he adds this rich, tasty sauce, plus some butter. Voila.

So now, the question - here's the mystery to me is nothing that you've just described is specifically sweet.


KRULWICH: Nothing is particularly sour. Nothing is determinately bitter.


KRULWICH: Or especially salty. So, well, so - but on the other hand, you knew it tasted good.

LEHRER: Yes. But it didn't just taste good. This was an epiphany. This was the best food you ever tasted in your life.

KRULWICH: Wait. Wait. Wait.


KRULWICH: But what are we tasting if it's not one of the four classic tastes?

LEHRER: So that's the mystery.

KRULWICH: And now, the mystery deepens. We go halfway around the world to Japan where there's an obscure chemist at the very same time. His name - how do you pronounce it? It's Kikunae Ikeda.

LEHRER: I think so.

(Soundbite of laughter)

LEHRER: He's eating a bowl of dashi, which is a Japanese soup.

KRULWICH: And he's thinking, as he tastes it, that…

LEHRER: It didn't taste like a little bit sour and a little bit salty.


LEHRER: It tasted like a completely separate taste sensation. But it sure is delicious.

KRULWICH: Same puzzle then.

LEHRER: Yes. It's the Escoffier puzzle.

KRULWICH: How can I be enjoying a taste that scientists say is not there? And by the way, he's a scientist.

LEHRER: He's a chemist.

KRULWICH: So he did a little chemistry.

LEHRER: He spent years trying to distill…


LEHRER: Years trying to distill, trying to figure out what part of this seaweed broth tasted so delicious.

KRULWICH: And he discovered that what he'd been tasting was…

LEHRER: Glutamate.

KRULWICH: Glutamate. It's found in most living things, but when they die, when organic matter breaks down - in an aging parmesan cheese or prosciutto; any fermented products - soy sauce, ketchup, Worcestershire sauce; in ripe things - a ripe tomato - all are rich with a form of glutamate called L-glutamate.

LEHRER: And when you cook meat in a pan the way Escoffier did, what you're essentially doing is releasing lots of glutamate.

KRULWICH: Is glutamate bitter?


KRULWICH: Is glutamate sour?


KRULWICH: Is glutamate salty?


KRULWICH: Is glutamate sweet?

LEHRER: No. But when you put it in your tongue, you know, it just fills your mouth with this full, rounded flavor, which is - it's like a low resonant chord played on a cello, you know, that, ooh.

KRULWICH: And in 1907, Kikunae Ikeda decided to name that ooh.

LEHRER: He calls it umami.


LEHRER: Umami. And he says it's…

KRULWICH: What does that mean?

LEHRER: Deliciousness.

KRULWICH: But when he publishes his findings in a chemistry journal and he says Aristotle is wrong, I'm now announcing a fifth taste.

LEHRER: No one believes him. All the great foods of the world seemed to revolve around the taste sensation of umami and yet it doesn't exist.

KRULWICH: And then almost a hundred years after that, however, In 2000 and again in 2002, a new generation of scientists with new tools discover that indeed, on our tongues, we do have receptors for glutamate.

LEHRER: Not just one type of glutamate receptor, but two types of glutamate receptors.

KRULWICH: So these were there all the time.

LEHRER: They were there all the time.

KRULWICH: (Unintelligible). And it was the chef and the soup-loving chemist who trusted their tongues over books and who insisted on a truth that they felt.

LEHRER: Yes. Why did it taste so good? And even though it shouldn't exist, even though the scientists say it shouldn't exist, it does exist.

KRULWICH: Chefs, after all, are artists. They know taste, not in a break-it-down-into-proteins kind of way, but in an I-know-I-can-taste-this kind of way. And because artists can feel so deeply and so exquisitely and so intuitively, sometimes they lead the scientists.

LEHRER: Yeah. I think it's strange for us. We think of, you know, what can you possibly learn from a chef? What can you learn about the anatomy of the tongue from a chef?

KRULWICH: Well, scientists now concede there are five tastes, not four. It's in the textbooks. They've named the fifth umami. So more than we realize, says Jonah Lehrer in his new book "Proust Was a Neuroscientist," artists, poets, novelists, composers and chefs figure out true things about the natural world often before scientists do.

LEHRER: You know, I think one interesting thing about all these artists I talk about in the book is that they took their art very seriously. They thought they were discovering real truth.

KRULWICH: And in this case, with a fifth taste, it was the chef who was right.

LEHRER: Yes. The chef was very right.

KRULWICH: Robert Krulwich, NPR News, New York.

MONTAGNE: Find out more about how Auguste Escoffier revolutionized French cuisine and get Podcasts of Robert Krulwich's stories at npr.org. Transcript provided by NPR, Copyright NPR.