How umami blew up taste

For thousands of years, there have been four basic tastes recognized across cultures. But thanks to Kumiko Ninomiya (a.k.a. the Umami Mama), scientists finally accepted a fifth. Could there be even more? (First published in 2022.) Guests: Kumiko Ninomiya, biochemist and former director of the Umami Information Center; Gary Beauchamp, former director of the Monell Chemical Senses Center; Sarah Tracy, historian of science; Camilla Arndal Andersen, neuroscientist; Paul Breslin, professor at Rutgers University For show transcripts, go to vox.com/unxtranscripts For more, go to vox.com/unexplainable And please email us! [email protected] We read every email. Support Unexplainable by becoming a Vox Member today: vox.com/members Learn more about your ad choices. Visit podcastchoices.com/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:01Speaker 00

  Support for the show comes from TikTok. If you listen to this show, you probably enjoy discovering new things. It is built into the DNA of the show that curiosity is its own reward and that there's always a deeper dive to do. And one place to explore some of the topics we've covered here is TikTok. Whether it's how to forecast volcanic eruptions, strange phenomena that the James Webb Space Telescope picked up near the beginning of time, or a literal deep dive on the ocean's deepest reefs, TikTok has a wealth of fascinating videos just waiting to be discovered. Your next discovery is waiting on TikTok. Learn more at tiktok.com/discovermore.

• 0:49Speaker 01

  This episode is brought to you by Indeed. You're ready to level up your business, but the pressure to find the right person to make that happen is intense. Indeed Sponsored Jobs can help carry the load. It boosts your job post to help it reach quality talent fast. Cut through the chaos with Indeed Sponsored Jobs. Get a $75 sponsored job credit at indeed.com/podcast. Terms and conditions apply. Hiring now? Then this is a job for Indeed Sponsored Jobs.

• 1:20Speaker 00

  This is Unexplainable. I'm Meredith Hottnott.

• 1:26Speaker 00

  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.

• 1:44Speaker 02

  My nickname is Umomimama. Many people don't know about my exact name, but they know Umomimama.

• 1:52Speaker 03

  Kumiko, the umami mama, is a biochemist and researcher.

• 1:56Speaker 02

  I am always talking about umami, umami, umami.

• 2:00Speaker 03

  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.

• 2:41Speaker 02

  If you eat long-cooked stew, or slapping chicken soup, or biting a slice of pepperoni and mushroom pizza, you feel a long-lasting and very comfortable aftertaste, and that's umami.

• 3:00Speaker 03

  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.

• 3:41Speaker 03

  Cheeses, cured meats, anchovies, tomatoes, mushrooms, seaweeds, they're all high in glutamate and all full of umami.

• 3:52Speaker 03

  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.

• 4:07Speaker 02

  We have a big problem about anti-MSG groups around the world, especially in the United States.

• 4:15Speaker 03

  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."

• 4:29Speaker 02

  People say, "No MSG. MSG is bad for health, and MSG is just chemical."

• 4:35Speaker 03

  This sparked a xenophobic panic across the US and demonized MSG.

• 4:41Speaker 04

  It's a neurotoxin. Chinese food is packed with MSG. MSG. MSG-laden Chinese food gives you headaches. Migraines. Allergies. Dizziness. And learning disabilities.

• 4:51Speaker 03

  I had 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.

• 5:10Speaker 05

  Yeah, you know what causes Chinese restaurant syndrome? Racism.

• 5:14Speaker 03

  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.

• 5:24Speaker 02

  My mission was to promote studies on glutamate and umami around the world.

• 5:31Speaker 03

  Ajinomoto tasked Kumiko with getting the scientific community to accept umami as its own basic taste.

• 5:38Speaker 02

  When I started working for research and studying umami taste, I was not so interested in the umami taste. My boss just say, "You are in charge of this work." And it's a kind of my life work.

• 5:55Speaker 03

  Did you know that it was gonna be your life work when you were first given that assignment?

• 5:59Speaker 02

  No.

• 6:03Speaker 02

  At that time, I was always thinking, uh, how to quit my job.

• 6:11Speaker 03

  She didn't quit. Instead, she launched a multidisciplinary, international, decades-long campaign that changed the field of sensory science forever.

• 6:21Speaker 02

  That was my big challenge.

• 6:23Speaker 03

  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?

• 6:43Speaker 06

  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.

• 6:54Speaker 07

  Listen to me, listen to me.

• 6:55Speaker 06

  Touch.

• 6:56Speaker 07

  Squishy.

• 6:57Speaker 06

  Odors.

• 6:57Speaker 07

  Ew.

• 6:57Speaker 06

  And tastes.

• 7:00Speaker 06

  What are your thoughts concerning the human senses? As meat and wine, our nourishment to the body, the senses provide nutriment to the soul. All that we perceive. Seeing. All the awareness. Hearing. All knowledge must come through the senses. I have an incredible sense of touch. All that we perceive. Tasting. All the awareness. Smelling. All knowledge must come through the senses. Doesn't make sense. Senor we love. Senor we love.

• 7:34Speaker 03

  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.

• 7:43Speaker 08

  Traditionally, it's been believed that there are four basic tastes that are built into us.

• 7:50Speaker 03

  This is Gary Beauchamp. 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, they're sweet.

• 8:10Speaker 08

  Sweet, that is supposedly a signal for calories and sugars.

• 8:15Speaker 03

  Next up is salty, a signal for sodium, which is an essential mineral for life.

• 8:20Speaker 08

  And so animals are built to be able to detect it and to like it. Then there's bitter.

• 8:25Speaker 03

  Bitter presumably helps us spit out poisons.

• 8:28Speaker 08

  But also many poisons at low levels are medicinal. And so it's been used actually as a way to identify medicines as well.

• 8:36Speaker 03

  And finally sour.

• 8:37Speaker 08

  Sour is this response to unripe foods. The exact function of that sensory system is not so clear.

• 8:46Speaker 03

  So the big four: sweet, salty, bitter, and sour.

• 8:50Speaker 08

  Those were the ideas that went back thousands of years. The Chinese, the Indians, the Greeks, many, many societies all through the world. Name those four as the basic part of taste.

• 9:04Speaker 03

  So in the 80s, when Gary started hearing about the campaign to make umami a basic taste, he was intrigued to a point.

• 9:12Speaker 08

  There was certainly a lot of skepticism in the US 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 amino acids and particularly MSG.

• 9:35Speaker 02

  My mission is not to sell MSG. My mission is to let people understand umami.

• 9:43Speaker 03

  Kumiko knew that scientists were wary of her motives, but she had a clear goal ahead of her.

• 9:48Speaker 02

  The goal is to make our network with scientists who are interested in umami research or glutamate in our body and food.

• 9:59Speaker 03

  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.

• 10:20Speaker 02

  Usually, the food scientist make a conversation with food scientist. But it was very difficult to make a good communication between food scientist and brain scientist, food scientist and nutritionist. That was very hard work to make a good communication among all the research area scientists.

• 10:46Speaker 03

  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.

• 10:55Speaker 09

  Like any other part of of human culture, science has fads.

• 11:00Speaker 03

  Sarah Tracy is a historian of science, and she has a book coming out all about the history of umami.

• 11:05Speaker 09

  Everyone talked about the brain in the 90s and the Human Genome Project, and then it was all about the gut in the aughts, you know? So I think umami is an interesting example of a very conscious and careful investment in the creation or fostering of scientific excitement.

• 11:24Speaker 03

  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.

• 11:35Speaker 09

  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.

• 11:49Speaker 03

  And so Kumiko, with the backing of Ajahn Amato, began organizing international symposiums on umami taste.

• 11:58Speaker 08

  They were very good meetings in the sense that they they brought the very best people who were doing taste work in the world.

• 12:04Speaker 03

  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.

• 12:17Speaker 08

  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.

• 12:28Speaker 03

  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.

• 12:37Speaker 08

  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.

• 12:55Speaker 03

  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.

• 13:06Speaker 02

  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.

• 13:26Speaker 03

  Brain scientists were shocked that glutamate, that they knew as a neurotransmitter, wasn't food at all. People kept calling it "yumami," not "umami." 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.

• 13:55Speaker 02

  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.

• 14:26Speaker 08

  There was a, not just a taste, but a feel. It was almost like it was thick, and it was mouth-watering.

• 14:37Speaker 03

  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.

• 15:18Speaker 03

  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.

• 15:41Speaker 10

  It's the sense we understand the least because it is so incredibly difficult to isolate.

• 15:49Speaker 03

  This is Camilla Andel Anderson. She's a neuroscientist at International Flavors and Fragrances, a corporation that makes ingredients for processed foods and beverages.

• 15:58Speaker 10

  So think of vanilla, think of banana, think of orange. All those are what you would perceive as smell.

• 16:06Speaker 03

  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.

• 16:22Speaker 10

  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 unpinch your nose, you would perceive the cinnamon. So that's really the smell.

• 16:48Speaker 03

  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 the 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 mouth feel, 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 mouth feel. And repeated tests showed that glutamate kept triggering a unique response in the

• 17:32Speaker 03

  brain, totally distinct from the big four. And yet, scientists like Gary wanted more. They wanted to know how umami worked.

• 17:41Speaker 08

  You really wanted a much more compelling story as to how it's different. What's the mechanism differentiating it?

• 17:50Speaker 03

  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-based 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.

• 18:33Speaker 03

  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.

• 19:07Speaker 08

  All at once, these receptors were identified.

• 19:11Speaker 03

  First, a bitter receptor was identified, and then a sweet receptor.

• 19:15Speaker 08

  2000, 2001, 2002, that was the golden age of discovery, and it was a very, very exciting time.

• 19:23Speaker 03

  During this taste receptor gold rush, Kumiko had one question.

• 19:27Speaker 02

  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.

• 19:41Speaker 08

  And remarkably, there was a separate one for glutamate.

• 19:46Speaker 03

  Right there, built into our tongues, was concrete evidence that umami was a taste.

• 19:51Speaker 08

  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.

• 20:05Speaker 03

  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.

• 20:22Speaker 02

  That was a big turning point.

• 20:25Speaker 03

  Were you excited when you heard the news that they had discovered it?

• 20:30Speaker 02

  Yes, yes, of course, yes. That was a very epoch-making research result. Everyone believed that umami is one of the basic tastes.

• 20:46Speaker 03

  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?

• 21:06Speaker 11

  Now the race is on to see if there's a sixth taste or a seventh or a thousandth taste.

• 21:10Speaker 03

  Coming up after the break.

• 21:19Noam Hassenfeld?

  Support for the show comes from Sonos. Hey, Sonos, give me some music.

• 21:25Noam Hassenfeld?

  All right, one of life's great mysteries. You're listening to music in the living room. You gotta grab something from the kitchen. You don't want to take the speaker with you, but you also don't want to miss that beat drop. And this is where I introduce you to the magic of Sonos. Sonos sent me a couple of speakers to try out, so I've got to move to here in the living room. And then I walk down the hall.

• 21:50Noam Hassenfeld?

  I get in here to the kitchen, and I got a brand new Sonos Play right here on the counter. I can open the fridge, grab a seltzer.

• 22:08Noam Hassenfeld?

  And yeah, I didn't miss a second. And I can make each speaker louder or softer in the Sonos app, or if I'm using AirPlay, so I can make it louder in the kitchen without blasting whoever is still in the living room. It's all just easy, and it sounds amazing. These speakers are crisp. They've got great bass. And I'm especially impressed with the new Sonos Play. It packs this truly awesome sound in a much smaller size. So I don't know, if I want to

• 22:41Noam Hassenfeld?

  head outside for a minute.

• 22:44Noam Hassenfeld?

  It's super easy. And yeah, pretty nice out. Visit sonos.com and build your system. Sonos, love the sound, feel the system.

• 22:59Speaker 00

  Support for the show comes from TikTok. Being curious is endlessly rewarding. There are few better feelings, in my opinion, than asking a question and then having that question lead you down a rabbit hole. Might even be the beginning of a new set of interests that was not on your radar beforehand. Maybe you're looking up at the night sky one night and you start to wonder what the most distant thing you can see with the naked eye is. One place to start searching for answers to a question like that is TikTok. First, you might discover a video about the Andromeda Galaxy. And then, next thing you know, you're learning how to find different

• 23:40Speaker 00

  stars, or how to identify constellations, or how different astronomical discoveries got made, or how constellations got their names. You don't need serious equipment to make serious discoveries. Start with a simple question, and suddenly, you're somewhere you never expected to be. Your next discovery is waiting on TikTok. Learn more at tiktok.com/discovermore. At tiktok.com/discovermore.

• 24:14Speaker 01

  This episode is brought to you by Indeed. You're ready to level up your business, but the pressure to find the right person to make that happen is intense. Indeed Sponsored Jobs can help carry the load. It boosts your job post to help it reach quality talent fast. Cut through the chaos with Indeed Sponsored Jobs. Get a $75 sponsored job credit at indeed.com/podcast. Terms and conditions apply. Hiring now? Then this is a job for Indeed Sponsored Jobs.

• 24:47Speaker 13

  Creamy, salty, sweet, and oaky nuttiness. You detect that? Oh, I'm detecting nuttiness.

• 24:54Speaker 03

  It's unexplainable. We're back. I'm Meredith Hodnot. And after Komiko'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.

• 25:35Speaker 03

  There could be a sixth basic taste, and a seventh, and an eighth. But by focusing on receptors, are they jumping the gun?

• 25:45Speaker 03

  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.

• 26:19Speaker 01

  Your attention, please. There is a new taste.

• 26:22Noam Hassenfeld?

  Researchers now say that fat should be considered the sixth taste. Well, duh, it's not the first.

• 26:29Speaker 03

  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.

• 26:47Speaker 10

  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.

• 26:57Speaker 03

  This is Camila Andal Anderson again.

• 27:00Speaker 10

  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 neuroactivation to this taste?

• 27:10Speaker 03

  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.

• 27:38Speaker 05

  It melts in the mouth.

• 27:39Speaker 03

  Crispy, crunchy, tender, crumbly, smooth, creamy, luscious? Fat is responsible for all of these touch parts of flavor.

• 27:50Speaker 10

  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.

• 27:59Speaker 03

  To test taste and taste receptors in isolation, Camilla rigged up some pretty wild experiments. Participants had to sit with their heads completely still.

• 28:08Speaker 10

  Strapping them onto a headrest.

• 28:11Speaker 03

  They wore these EEG caps with sensors all over them to measure their brain activity, and they were told to hold their breath.

• 28:17Speaker 10

  So they couldn't smell.

• 28:18Speaker 03

  And then they stuck out their tongues.

• 28:20Speaker 10

  And we would pump three types of milk on the tongues of people. So that would be either skim milk, whole milk, or cream.

• 28:28Speaker 03

  But they couldn't swallow or close their mouths.

• 28:31Speaker 10

  The taste solution would just sort of drip off into a bowl standing underneath.

• 28:36Speaker 03

  So you'd need a bib in this setup as well.

• 28:38Speaker 10

  I did actually use one, yeah.

• 28:42Speaker 03

  And after all of this, Camilla did find some interesting brain signals.

• 28:46Speaker 10

  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.

• 28:58Speaker 03

  So some promising evidence of a signal of fat taste being processed in the brain.

• 29:03Speaker 14

  But what exactly is going on, we're not sure.

• 29:06Speaker 03

  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.

• 29:17Speaker 14

  In 20 years from now, we'll probably have come to some kind of a consensus on it, but we're not there yet.

• 29:23Speaker 03

  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.

• 29:35Speaker 14

  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.

• 29:48Speaker 03

  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.

• 30:14Speaker 14

  In the pancreas.

• 30:16Speaker 03

  On the skin.

• 30:17Speaker 14

  In the intestine.

• 30:18Speaker 03

  In the nose.

• 30:19Speaker 14

  In the brain. All of these places are using the exact same machinery, the same receptors.

• 30:25Speaker 03

  These receptors aren't hooked into our conscious perception of taste.

• 30:29Speaker 14

  Well, thankfully, you can't taste the inside of your small intestine with the taste receptors there.

• 30:34Speaker 03

  Think of it like your pancreas is constantly tasting your blood to see how much insulin to produce. These taste receptors are tools.

• 30:43Speaker 14

  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.

• 31:01Speaker 03

  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.

• 31:11Speaker 14

  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 their relationship to each other?

• 31:27Speaker 03

  It's a bit like the debate around whether or not Pluto is a planet. Pluto was killed because if Pluto is 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?

• 32:08Speaker 03

  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.

• 32:19Speaker 14

  What is that spatial galaxy or universe of taste?

• 32:25Speaker 03

  So our scientific definition of taste is growing and evolving, but 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.

• 32:48Speaker 09

  You know, it's exciting. I understand. I get it. Umami is cool.

• 32:54Speaker 03

  This is Sarah Tracy again, the science historian.

• 32:58Speaker 09

  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, our understanding of taste and smell work comes to us by virtue of corporate research.

• 33:13Speaker 03

  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.

• 33:30Speaker 09

  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.

• 33:47Speaker 03

  And that brand was painstakingly built over decades. First, within the scientific community, and then beyond.

• 33:56Speaker 09

  An enormous amount of science communication and promotion went into popularizing umami among chefs and food writers and tastemakers.

• 34:06Speaker 02

  So the company or aginomoto company's policy is science first, then communication.

• 34:15Speaker 02

  Based on science.

• 34:16Speaker 03

  After umami was widely accepted as a basic taste, Kumiko shifted the umami campaign to the culinary world.

• 34:24Speaker 02

  And I think that umami is a taste. So the taste is very important for chefs to create the good meals and excellent dishes. That's why I decided to make a conversation with chefs, top chefs.

• 34:43Speaker 03

  When Kumiko says "top chefs", she means "the most famous", the most influential chefs in the world at the time.

• 34:51Speaker 02

  Because top chefs has a big voice. And maybe the young chefs try to follow the top chefs. So that was a very, very challenging for me. That was very hard work.

• 35:07Speaker 03

  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.

• 35:19Speaker 02

  Umami is one of the very fashionable foods in the United States. And people are very interested in umami. So it's a very good opportunity for us to promote more about umami.

• 35:35Speaker 03

  Where we draw the line on how to define a taste, maybe 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.

• 35:51Speaker 02

  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 use MSG because I have many restaurants in the United States. And there are so many people hate MSG. Don't waste your time.

• 36:19Speaker 02

  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.

• 36:46Speaker 02

  I was so surprised. What did he say?

• 37:07Speaker 15

  This episode was reported and produced by Meredith Hadenot. It was edited by Catherine Wells, Noam Hassenfeld, Brian Rusnick, with help from Manning Wen and Bert Pinkerton. Real team effort. Music by Noam. Christian Ayala handled the mixing and sound design. Research and fact checking by me, Richard Seema. And Tori Dominguez is our audio fellow. Special thanks to Nancy Rosson, 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.

• 37:50Speaker 15

  And the awesome umami song is called "Umami" by Noishe. 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/unexplainable. And if you have thoughts about the show, you can always email us at [email protected]. Or you could leave us a review or a rating, which we would love as well. Unexplainable is part of the Vox Media Podcast Network.

• 38:32Speaker 16

  When everything feels nonstop, movement becomes the pause. So give Lululemon this holiday season. Smooth, seamless running gear builds momentum through every mile. Targeted support adds steadiness to every pulse and hold. And dynamic stretch expands presence through every pose. Give the feeling. Shop in-store and on lululemon.com.

• 39:01Speaker 17

  Sam's Club is the club for every holiday club. Guess who's joining the club this season? Walmart Plus. Yep, Sam's Club Plus membership now comes with Walmart Plus at no extra cost. Two memberships, one great price. Just $120 a year can save you time and over $700. Want to get in on the membership duo of the century? Visit sam'sclub.com. Come join us. Sam's Club.