Making Sense: The Umami Mama
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It's Unexplainable. I'm Noam Hassenfeld. And this is our fourth episode of Making Sense, our series on some of the most perplexing questions about our senses. Last week, we talked about the mysteries of smell. And this week, senior producer Meredith Hodnot brings us a story about the fuzzy borders of our sense of taste. The science behind how things taste has been an organizing principle in my life.

It's led me to chemistry labs and test kitchens and science podcasts. But I've never met anyone as devoted to the science of a single taste as Kumiko Ninomiya. My nickname is Umami Mama. Many people don't know about my exact name, but they know Umami Mama. Kumiko, the Umami Mama, is a biochemist and researcher. I am always talking about Umami, Umami, Umami, Umami.

The umami that Kumiko is always talking about has always been a part of food, but it wasn't identified until 1908. That year, a Japanese chemist, Kikunae Ikeda, distilled pure glutamate salt from big sheets of a seaweed called kombu, a foundational ingredient in Japanese cuisine.

This salt, monosodium glutamate, or MSG, was more than just salty, but it wasn't exactly sour or bitter or sweet either. Ikeda believed that MSG had a totally distinct taste and that it was the basis of deliciousness, or umai in Japanese, and so he called it umami.

Umami is like a baseline.

In a dish, you might not even notice it, distracted by the harmonies of sweet and sour and salty and maybe a discordant note of bitter. But umami is there. It's rich. It's deep. It builds over time. In some ways, umami is the taste of cooking itself. It's the taste of proteins blasted apart through heat or fermentation. And at the heart of umami is one of those protein pieces: glutamate.

And while MSG is a pure, concentrated form of glutamate, glutamate and the umami it evokes occur naturally in foods all over the world. Cheeses, cured meats, anchovies, tomatoes, mushrooms, seaweeds, they're all high in glutamate and all full of umami. Ikeda was the first to really give umami a name and to sell it. He founded Ajinomoto, which became one of the biggest MSG companies in the world.

But in the 1970s, Ajinomoto encountered a problem. We have a big problem about anti-MSG groups around the world, especially in the United States.

A letter to the editor in the New England Journal of Medicine suggested that MSG caused weakness and dizziness, chest pain, and all these other vague symptoms they called Chinese restaurant syndrome. People say no MSG. MSG is bad for health, and MSGs are just chemical. This sparked a xenophobic panic across the U.S. and demonized MSG.

It's a neurotoxin. Chinese food is packed with MSG. MSG. MSG-laden Chinese food gives you headaches. Migraines. Allergies. Dizziness. And learning disabilities. I have MSG poisoning. I know. Ajinomoto and other MSG companies poured tons of research dollars into proving that their products were safe. Private institutions, public government research, it all came back with the same conclusion. MSG is safe.

You know what closes Chinese restaurant syndrome? Racism. But a dark cloud of bad press still hung over the MSG industry.

they wanted to change the conversation entirely. And so Ajinomoto hired Kumiko. My mission was to promote studies on glutamate and umami around the world. Ajinomoto tasked Kumiko with getting the scientific community to accept umami as its own basic taste. When I started working for research and study on umami taste, I was not so interested in the umami taste.

My boss just said, you are in charge of this work. And it's kind of my life work. Did you know that it was going to be your life work when you were first given that assignment? No. At that time, I was always thinking how to quit my job.

She didn't quit. Instead, she launched a multidisciplinary, international, decades-long campaign that changed the field of sensory science forever. That was my big challenge. And in the process of pushing for worldwide recognition of umami, her work raised more questions. How many tastes are out there, waiting for the scientific establishment to recognize? And how do we even define a taste?

to begin with. All knowledge must come through the senses. All that we perceive and all of the awareness of our daily existence. Light. Double rainbow. Oh my God. Sound. Listen to me. Listen to me. Touch. Squeezy. Odors. Ew. And tastes. Mmm. What are your thoughts concerning the human senses? As meat and wine are nourishment to the body, the senses provide nutriment to the soul.

All that we perceive, see, all of the awareness, hearing, all knowledge must come through the senses. I have an incredible sense of touch. All that we perceive, tasting, all of the awareness, smelling, all knowledge must come through the senses. Doesn't make sense. So now we've lost. Please, so now we've lost. So what was Kumiko trying to achieve here? What does it mean for something to be a taste?

For thousands of years, it was a pretty exclusive club. Traditionally, it's been believed that there are four basic tastes that are built into us. This is Gary Beecham. He's the former director of the Monell Chemical Senses Center, a nonprofit research institute. Gary's interested in the big four tastes, but also the evolutionary narrative of how each taste helped our ancestors answer the question, what should I put in my mouth?

So, first off, there's sweet. Sweet, that is supposedly a signal for calories and sugars. Next up is salty, a signal for sodium, which is an essential mineral for life. And so animals are built to be able to detect it and to like it.

Then there's bitter. Bitter presumably helps us spit out poisons. But also many poisons at low levels are medicinal. And so it's been used actually as a way to identify medicines as well. And finally, sour. Sour is this response to unripe foods. The exact function of that sensory system is not so clear. So the big four.

Sweet, salty, bitter, and sour. Those were the ideas that went back thousands of years. The Chinese, the Indians, the Greeks, many, many societies all through the world named those four as the basic part of taste.

So in the 80s, when Gary started hearing about the campaign to make umami a basic taste, he was intrigued, to a point. There was certainly a lot of skepticism in the U.S. that this was really maybe something that was not a real taste, or it wasn't certainly a basic taste in the same way sweet, sour, salty, bitter is. And maybe it was all a marketing ploy to try to sell umami

amino acids and particularly MSG. My mission is not to sell MSG. My mission is to let people understand umami. Kumiko knew that scientists were wary of her motives, but she had a clear goal ahead of her. The goal is to make a network with scientists who are interested in umami research for glutamate in our body and food.

Glutamate is an amino acid, a building block for proteins. It's important in food science, nutrition, physiology, but it's also a neurotransmitter, like one of the most abundant chemicals in the brain.

So there was a lot of research interest in glutamate across a lot of fields. And Kumiko wanted these researchers to communicate with each other. Usually, the food scientists make a conversation with food scientists. But it was very difficult to make a good communication between food scientists and brain scientists.

food scientists and nutritionists. That was very hard work to make a good communication among all the research areas scientists. Kumiko thought that good communication could get these scientists excited about studying umami as a taste.

And that excitement was the key to her plan. Like any other part of human culture, science has fads. Sarah Tracy is a historian of science, and she has a book coming out all about the history of umami. Everyone talked about the brain in the 90s and the human genome project, and then it was all about the gut and the odds, you know? So I think umami is an interesting example of a very conscious and careful approach

an investment in the creation or fostering of scientific excitement. The idea of whether umami was a taste had the potential to be the next cool thing to study. Like, how do you even define a new taste? There hadn't been one for thousands of years. We've had the basic four for millennia. It takes a lot of PR money. It takes a lot of research dollars. It takes a lot of impetus to change our ideas about how to define the body.

And so Kumiko, with the backing of Ajinomoto, began organizing international symposiums on umami taste. They were very good meetings in the sense that they brought the very best people who were doing taste work in the world. Gary met neurologists and nutritionists, molecular biologists and medical doctors, all studying glutamate and all brought together by Kumiko to discuss whether umami was a basic taste.

What they were cleverly doing is trying to get people interested in doing research in this area. And that was, in retrospect, a good thing, although it could have been a dangerous thing, of course.

dangerous because industry-sponsored science is kind of suspect. Companies often get the results that help them tell the stories that they want to sell. There was no question that there was funding coming from commercial organizations, which had an ulterior motive, you could say. And I think that that led people to actually lean over the other direction to try to make sure that the research they were doing was not influenced by anything like that.

Throughout the 80s and 90s, Kumiko organized these umami taste conferences. But she kept coming up against a problem: the translation from glutamate to umami. In that time, the researchers themselves don't know about the taste quality of umami. The scientists know about the glutamate in the brain, glutamate in the body, and glutamate in foods, but they don't know about what exactly umami is.

Brain scientists were shocked that glutamate, that they knew as a neurotransmitter, wasn't food at all. People kept calling it umami, not oomami. And because the quality of umami was so subtle, that building baseline under the flash and flare of other tastes,

Kumiko put together tasting sessions for these scientists. She believed that they couldn't fully debate whether umami was a taste if they didn't have the personal experience and vocabulary to talk about it. That's why I think that tasting is the most important part to let them understand the taste quality of umami. Because we are talking about the taste of umami.

So through the symposium, I tried to make an opportunity to have a tasting session about umami taste and how to find umami in the tomato or cheese. And they gradually understand what umami is. There was a, not just a taste, but a feel. It was almost like it was thick and it was mouth-watering. It was delicious.

Gary and other scientists understood that umami was a unique sensory experience. But did that make it a taste? Scientists scoured everything they knew about taste. How chemicals in food interact with the tongue, how the tongue sends signals to the brain, how the brain processes those signals. They looked at animal models to see if other species could taste amino acids like glutamate. And in Gary's mind, if umami was a taste, it probably had some evolutionary explanation.

So he wondered, could umami be a taste signal for proteins, just like sweetness was thought to signal calories and salty sodium? So he worked with malnourished infants to see if they were particularly drawn to the taste of glutamate. And he found that all the infants he studied liked the taste of MSG. Everywhere they looked, there were promising clues, but there's no clear-cut answers. No way to definitively say that umami was a taste.

In large part, because taste is just really hard to study. It's the sense we understand the least.

Because it is so incredibly difficult to isolate. This is Camilla Andel-Anderson. She's a neuroscientist at International Flavors and Fragrances, a corporation that makes ingredients for processed foods and beverages. So think of vanilla, think of banana, think of orange. All those are what you would perceive as smell. A lot of what we think we're tasting is actually a smelling food from inside our mouths.

Take a cookie, for instance. You smell the vanilla and the chocolate chips and the butter wafting up from the back of your mouth into your nose as you eat it.

One good way to actually differentiate between smell and taste is to pinch your nose. If you pinch your nose, you wouldn't be able to smell. And so if you put, let's say, a bit of cinnamon in your mouth, you pinch your nose, then all you would be detecting is a little bit of bitterness. That's the taste. And when you then un-pinch your nose, you would perceive the cinnamon. So that's really the smell.

And even when you take the nose out of the equation entirely and just focus on sensing chemicals in the mouth, the borders of taste are still fuzzy. Like, take spiciness. Is spiciness a taste? It's a molecule, capsaicin, that you're sensing in the mouth, but it's actually activating pain and heat receptors, so it's considered more of a kind of touch.

The same goes for astringency, menthol, and qualities like slipperiness. Those are all mouthfeel, not taste. But by the 90s, researchers were pretty sure that umami wasn't an aroma or a touch, though it did have an interesting mouthfeel. And repeated tests showed that glutamate kept triggering a unique response in the brain, totally distinct from the big four.

And yet scientists like Gary wanted more. They wanted to know how umami worked. You really wanted a much more compelling story as to how it's different. What's the mechanism differentiating it? And so the conversation of whether umami was a basic taste pivoted to molecular biology.

This was around the late 90s, and molecular biology was all the rage. The Human Genome Project was a multi-billion dollar international collaboration to map out all the billions of DNA base pairs in the human genome. The thought was that this would unlock the blueprint for the human body and usher in a whole new age of genetic understanding. And in 2000, scientists started using an early draft of the Human Genome Project to zero in on taste receptors.

A taste receptor is really where the rubber meets the road in terms of taste. Like, looking at your tongue in the bathroom mirror, you'll see all sorts of bumps and grooves, and those are little organs called papillae. Zooming in, the papillae are packed with taste buds, and each taste bud has like 50 to 100 taste cells. Zooming in even further, on the tip of each of those cells is a taste receptor.

a carefully folded little protein that interacts with food on a molecular level. And so researchers all around the world were racing to find the genes that coded these receptors for all the tastes. All at once, these receptors were identified. First, a bitter receptor was identified, and then a sweet receptor. 2000, 2001, 2002, that was the golden age of discovery, and it was a very, very exciting time.

During this taste receptor gold rush, Kumiko had one question. What is the taste receptor of umami? So we tried to promote research in the United States to talk more about the taste receptor of glutamate. And remarkably, there was a separate one for glutamate. Right there, built into our tongues, was concrete evidence that umami was a taste.

The fact that there was a receptor for this really convinced a lot of people that if nature has given us this sensory apparatus to detect it, it must be real and it must be important. For Kumiko, this was the culmination of years and years of work.

organizing conferences, doing taste demonstrations, promoting research. Scientists were looking for glutamate receptors because Kumiko convinced them that there was something to look for. That was a big turning point. Were you excited when you heard the news that they had discovered it? Yes, yes, of course, yes. That was a very epoch-making research result.

Everyone believed that umami is one of the basic tastes. Umami was accepted around the world as basic taste number five. But in pushing the scientific understanding of taste beyond the big four, umami opened up a whole new world.

How many tastes could be out there? Are there just five basic tastes now? Or could there be way more? Now the race is on to see if there's a sixth taste or a seventh or a thousandth taste. Coming up after the break. Support for Unexplainable comes from Greenlight. People with kids tell me time moves a lot faster. Before you know it, your kid is all grown up. They've got their own credit card.

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The Walt Disney Company is a sprawling business. It's got movie studios, theme parks, cable networks, a streaming service. It's a lot. So it can be hard to find just the right person to lead it all. When you have a leader with the singularly creative mind and leadership that Walt Disney had, it like goes away and disappears. I mean, you can expect what will happen. The problem is Disney CEOs have trouble letting go.

After 15 years, Bob Iger finally handed off the reins in 2020. His retirement did not last long. He now has a big black mark on his legacy because after pushing back his retirement over and over again, when he finally did choose a successor, it didn't go well for anybody involved.

And of course, now there's a sort of a bake-off going on. Everybody watching, who could it be? I don't think there's anyone where it's like the obvious no-brainer. That's not the case. I'm Joe Adalian. Vulture and the Vox Media Podcast Network present Land of the Giants, The Disney Dilemma. Follow wherever you listen to hear new episodes every Wednesday.

Creamy, salty, sweet, and oaky nuttiness. You detect that? Oh, I'm detecting nuttiness. It's unexplainable. We're back. I'm Meredith Hodnot. And that's...

And after Kumiko's decades-long campaign, umami was accepted as a basic taste when researchers found a receptor for glutamate. This blew up the millennia-old conception of the Big Four, sweet, salty, bitter, and sour. And receptors became a new benchmark for the definition of a basic taste. But the taste receptor discoveries didn't stop with glutamate.

Over the last 20 years, scientists have found evidence for taste receptors that detect fat, starch, calcium, even metals like iron. And scientists started to claim that some of these might also be fundamental basic tastes. There could be a sixth basic taste and a seventh and an eighth. But by focusing on receptors, are they jumping the gun?

I mean, sure, finding a glutamate receptor was the critical piece of evidence that tipped the scientific community towards accepting umami as a basic taste. But that came after decades of sensory, perceptual, and neurological data. Not to mention over a century of Japanese food traditions. This new crop of taste candidates are starting from the receptor and working backwards. They still need to build up all that sensory and neurological research.

So let's focus on one of the most popular candidates, fat. Your attention, please. There is a new taste. Researchers now say that fat should be considered the sixth taste. Well, duh, it's not the first. In 2015, researchers started pushing for fat to be the sixth taste because they had found a taste receptor for fatty acids, the molecular fragments of fat.

But they still need to prove that those receptors send a conscious signal to the brain, just like scientists had done for umami. The thing that's still very much under investigation is whether that signal from the taste receptor is sent to the brain, like whether we actually use the information. This is Camilla Andel Anderson again. So that's where the kind of science I do comes into play, where we actually look at the brain and look at

do we see a neural activation to this taste? All taste is hard to isolate from the other senses, but fat is particularly tricky. Fat is an incredible solvent, so it's this great vehicle for aromatic compounds, the smell part of flavor. I mean, just think about garlic infused olive oil.

Fat also plays a fundamental role in the texture, the touch of foods. Chocolate is so luxurious because cocoa butter melts just around body temperature. So it literally melts in your mouth. It melts in the mouth. Crispy, crunchy, tender, crumbly, smooth, creamy, luscious. Fat is responsible for all of these touch parts of flavor.

We know that we smell fat and we know that we sense the texture of fat. But the next question is whether we also taste fat. To test taste and taste receptors in isolation, Camilla rigged up some pretty wild experiments.

Participants had to sit with their heads completely still. Strapping them onto a headrest. They wore these EEG caps with sensors all over them to measure their brain activity. And they were told to hold their breath. So they couldn't smell. And then they stuck out their tongues. And we would pump three types of milk on the tongues of people. So that would be either skim milk, whole milk, or cream. But!

but they couldn't swallow or close their mouths. The taste solution would just sort of drip off into a bowl standing underneath. So you'd need a bib in this setup as well. I did actually use one, yeah. And after all of this, Camilla did find some interesting brain signals. What we saw was that we were able to discriminate the response, the brain response to the skim milk and the cream. There was something we were registering that was different between these two.

So some promising evidence of a signal of fat taste being processed in the brain. But what exactly is going on, we're not sure. Paul Breslin is a scientist at Rutgers University. He also works at the Monell Center. And he studies taste pathways, the path a receptor signal takes from the tongue to the brain. In 20 years from now, we'll probably have come to some kind of a consensus on it, but we're not there yet. All of the potential six tastes are in this position.

calcium, starch, metallic. Labs around the world are trying to build the narrative, build the case of whether these should be considered tastes. It's intriguing to say, like, we can taste fat or we can taste potassium or we can taste calcium or maybe we can taste water. Those are all interesting stories. But collectively, what is taste is really the more interesting question. What is taste?

Well, our depth of understanding has certainly grown over the past 40 years. And because there was a concentrated research effort to dig down into the molecular machinery of taste, we've learned a lot about how our whole body interacts with the chemical world around us. Because once scientists started finding taste receptors in the mouth,

They started finding them all over the body. In the lungs. In the pancreas. On the skin. In the intestine. In the nose. In the brain. All of these places are using the exact same machinery, the same receptors. These receptors aren't hooked into our conscious perception of taste. Well, thankfully you can't taste the inside of your small intestine with the taste receptors there. Think of it like your pancreas is constantly tasting your blood to see how much insulin to produce.

These taste receptors are tools. So if you think of all the different ways you can use a hammer, you can use it to hammer something into place, you can use it to remove something, you can use it to pull nails, you can use it to put nails in. It's the same receptor in every single one of those places, but in each place it serves a different purpose.

One scientist told me that if we had found these receptors on the pancreas, we would have called them pancreatic receptors and would have been shocked to find them on our tongues. The fundamental issue, the fundamental question really becomes, what is the totality of the space? What is everything that we can experience in that chemosensory world? And how do these things fit together? What is the relationship to each other? It's a bit like the debate around whether or not Pluto is a planet.

Pluto was killed because if Pluto's a planet, then all these other moons and dwarf planets like Ceres, they could be planets too. And some scientists have argued that we should have like over 150 planets. In our solar system of taste, the big four, salty, sweet, bitter, and sour, they might be like gas giants, the big guys, right? Whereas Umami is much more subtle. So maybe it's more like a little small rocky planet like Earth or Venus. But moving out,

Where do we draw the line? And ultimately, does it really matter? Pluto is still out there, still spinning around the sun, no matter how we choose to categorize it. And for taste, wherever we draw the line, there's still so much to explore. What is that spatial galaxy or universe of taste? So our scientific definition of taste is growing and evolving. Tastes are also culturally defined.

The general public might not care about the intricacies of the molecular biology, the glutamate, the receptors. But now they care about umami. You know, it's exciting. I understand. I get it. Umami is cool. This is Sarah Tracy again, the science historian. To me, I don't think that we would have umami without that industry influence.

But I mean, this is also the way so much of our understanding of taste and smell work comes to us by virtue of corporate research. Taste is big business. It's an industry. And a lot of what we know about sensory science has its roots in the modern industrial food system. Our current understanding of umami as a taste was part of a larger campaign to change the conversation about MSG. And it worked.

Without a name for the thing, how can you think with it or live with it? Our names and our language do, in a way, forge our reality. And so whether we call it umami or not has real effects in the world. It's certainly a fantastic branding proposition. And that brand was painstakingly built over decades.

first within the scientific community and then beyond. An enormous amount of science communication and promotion went into popularizing umami among chefs and food writers and tastemakers. So the company or Ajinomoto company's policy is science first, then communication based on science.

After umami was widely accepted as a basic taste, Kumiko shifted the umami campaign to the culinary world. And I think that umami is a taste. So the taste is very important for chefs to create good meals and excellent dishes. That's why I decided to make a conversation with chefs, top chefs.

When Kimiko says top chefs, she means the most famous, the most influential chefs in the world at the time. Because top chefs has a big voice.

And maybe the young chefs try to follow the top chefs. So that was very, very challenging for me. That was very hard work. The popularity of Japanese cuisine exploded at the same time that food science and molecular gastronomy took hold of the culinary imagination. And suddenly, umami was everywhere. Umami is one of the very fashionable words in the United States today.

And people are very interested in umami. So it's a very good opportunity for us to promote more about umami. Where we draw the line on how to define a taste may be kind of arbitrary, but it has real-life effects. Ultimately, we live in a different scientific and culinary world because of the Umami Taste Campaign and the Umami Mama.

My nickname was given by Nobu. Nobu Matsuhisa is a very famous Japanese chef around the world. And when I first met him, he told me, "Don't come to me. You will start talking about MSG." And I never used MSG because I had many restaurants in the United States. And there are so many people hate MSG. Don't waste your time.

I every month visit him to talk about umami. And then he gradually understand what I want to do. And after that, he started talking about umami by himself. And he introduced me to the guest in the restaurant. She is world famous umami mama. So...

I was so surprised. What did he say? This is the fourth episode of our Making Sense series. Next week, sight and the limitations of the mind's eye. And you know, I'd always read about things like picturing your loved one's face and this and that. And I was like, why can't I picture anyone's face? This episode was reported and produced by Meredith Hoddenot.

It was edited by Catherine Wells, Noam Hassenfeld, Brian Resnick, with help from Mandine Nguyen and Bird Pinkerton. Real team effort. Music by Noam, Christian Ayala handled the mixing and sound design. Research and fact checking by me, Richard Sima, and Tori Dominguez is our audio fellow. Special thanks to Nancy Rawson, Johnny Drain, Eliza Barclay, Nicola Twilley, and Emily Hanselman.

If you want to learn more about the history of umami, keep an eye out for Sarah Tracy's upcoming book, Delicious, A History of Monosodium Glutamate, Umami, and the Dysphoric Sublime. And the awesome umami song is called Umami by Noishne. To read more about some of the topics we cover on our show or to find episode transcripts, check out our site at vox.com slash unexplainable.

And if you have thoughts about the show, you can always email us at unexplainable at vox.com. Or you can leave us a review or a rating, which we would love as well. Unexplainable is part of the Vox Media Podcast Network. And we will see you next week for episode five of Making Sense.