Short Wave - TASTE BUDDIES: Y U Salty?

Episode Date: April 19, 2022

Salt has such a rich history that it was once (and is perhaps still) a sign of wealth. In this latest installment of our series on flavor and taste, "Taste Buddies," Scientist-in-Residence Regina G. Barber goes on a salty flavor journey with scientist Julie Yu. Along the way, Julie explains salt's essential role in our daily lives and how it affects our perception of food. Follow Regina on Twitter @ScienceRegina. Email Short Wave at [e-mail] pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. SupNNNs, host Emily Kwong here with scientist and residence Regina Barber. Regina, hey. You're bringing our next installment of our series that is just a bid to eat good food. It is called Taste Buddies. And today we're going to talk about salt. I love salt. Me too.

So excited for this. Yeah, I love salt. It brings back fond memories of my mom's cooking. She had so many delicious dinners or there was a lot of soy sauce and perfectly seasoned vegetables. I mean, you know what's up being Chinese American also, right? We love our salt. My dad eats sardines straight out of the tin, and we have all these salt-preserved foods just randomly around the house. But remind us, scientists and residents, what exactly is salt?

Well, it's not an easy answer because there is the chemist's definition of salt, and then there is the non-chemist or home cook or just regular eaters definition of salt. And one of the most famous of these is sodium chloride, which we know as table salt. So that was Dr. Julie Yu, and she's a senior scientist at the Exploratorium in San Francisco, where she uses cooking to help people learn about science. But I just want to say salt also has a really cool history. Yeah, I've read somewhere that for century, salt actually was used as currency. Like it was equal to wealth because salt is so useful in preserving meat and fish. It's very valuable.

Yeah, soldiers and workers were sometimes paid in salt. Cool. Like the word salary comes from salarium because Saul is the Latin word for salt. And actually back then, they used to have salt in these beautiful, expensive dishes on their tables just to show their guests how wealthy they were. Yeah, our bodies also need salt. Right, but not too much. So today on the show, we get salty. And I talk to Julie U about why salt is essential to our daily lives.

And most importantly, how it takes. That's what I'm here for. I won't listen to that part. I'm Emily Kwong and I'm Regina Barber. And this is Shortwave, the Daily Science Saltcast from NPR. Okay, Julie U, in a bit we're going to do some taste testing of different salts. But before we get there, let's talk about cooking. When we're cooking, we don't want to use too much salt or too little. Can you tell us about why people need salt? Like, what does it do to our bodies? So people need salt in their diet. And again, when we're talking about diet, we're usually referring to sodium. And sodium is a really important ion in a lot of our processes, our neurological processes that helps with our blood pressure regulation and just a lot of the biochemistry that our bodies need to do require sodium. Now, sodium is actually not present in large quantities in most food, and yet people typically

consume probably more sodium every day than they need. And that's because we add sodium to almost all of our processed food, any manufactured food. So most of us are very far from suffering any kind of sodium deficiency. So what happens if we get too much? Why is it dangerous? Well, one thing and maybe the most common thing that people are worried about when they're looking at their sodium intake is high blood pressure or hypertension. Increased amounts of sodium can increase your blood pressure. And that can cause all.

kinds of systemic problems. Got it. So Julie, let's get to our taste test of different salts. And as we taste them, maybe we can talk about how they're used in cooking. Sure. I have a variety right here. So which one should we do? Should we do table salt first? Because that's the one that maybe everyone has. Yes, I have generic unlabeled table salt. So I'm just going to sprinkle some on my plate. I have to like pop it open. Sprinkle some. So this table salt, it's super small, right? Like really granule. People get it confused with sugar. Yes, it's easy to confuse, and usually I do a little taste test if I'm confused. Where do we get table salt? What does it come from? Table salt comes from two main sources. It either comes from salt mines, so this is salt that has turned into rock over

hundreds of millions of years, or it comes from salty water. And actually, I mean, even the mines, originally, once upon a time, it was salty water. Cool. All right, so let's do kosher. Sure. So the chunks are bigger. Yeah, these are definitely coarser grains, and I just took a pinch because I have mine in a little salt cellar here, and I was able to grab a bunch and sprinkle it onto my plate. And that's one of the reasons why cooks like it so much is because you can take your hands and control a specific amount of salt, which is a little harder to do with the table salt. How does it taste? It tastes, I mean, it tastes saltier because there's more. So how does it taste to you? The actual flavor tastes the same. same to me. And I would say it probably tastes saltier because you put more, but I think it also tastes saltier because it has a greater surface area to volume ratio. So for a given amount of salt, it's actually hitting more portions of your tongue before dissolving and getting kind of swallowed down with the rest of your saliva. One interesting thing that that results in is kosher salt turns out

to be less dense than table salt. Because the shapes are irregular, they don't pack as perfectly as table salt does. So that really makes a difference when you're cooking. And if you have a recipe that says one teaspoon of salt, if you're going by volume, one teaspoon of iodized table salt is going to have more salt than one teaspoon of kosher salt. And so when you're looking at a recipe, It really matters what kind you're using. So should we try, let's try the fancy sea salt flakes. Sure. I'm going to open up my molden.

I have mine in a little mason jar here, so I'm just going to open that up. Oh, it's beautiful. Oh, my God. So what do you find beautiful about it? It's like very crystally. It almost looks like snow. It almost looks like snow. It's crystallized.

So you can actually see that it has this structure on a three-dimensional scale. Right. The mold and salt, you can actually see that it's, flakes. Yeah. These flakes. They're huge. They're huge.

And they're actually really delicate. So these crystals form. And you might be able to see in some of your bigger flakes. It kind of has a pyramid structure. And this salt, because it's just harvested right off the lake, it has sodium chloride in it, and it also has other minerals. And most sea salts, if they taste different from your table salt, it's probably because of those additional minerals that are not present in huge.

amounts, but they might be present enough for you to taste. Now, the malden salt is what's called a finishing salt because you really want to take advantage of that texture, right? So if you think about baking a chocolate chip cookie and sprinkling some of this salt on top, you're really taking advantage of the crunch of its texture and also a concentrated little burst of salt. I want us to taste something called a thousand-year-old egg. I know them by their Chinese name, which is Pida. Yeah. So I'm opening mine up right now, and they're, there's a duck eggs that have been preserved in salt and they look really dark. And it almost looks like a dinosaur egg on the outside. What does yours look like? The shell of yours. Mine came

individually wrapped. And so I finally got mine out of the package. And I have to say I did hear the delivery driver basically chuck this package onto my porch like I heard the thud. And as well packaged as these are, mine are already a little cracked. Oh my God, no. That's okay. They smell fine. The outside of the egg, I would say, is like this light gray-blueish hue with some darker spots. So I'm going to crack mine. Yeah, here we go. Yep. Okay. So my egg, now that I have completely peeled, it is this dark brown, I feel like there's a little maroonish hue in here. And mine actually has, I got a special one, this snowflake pattern on it. Oh, mine does too. Mine totally has a snowflake pattern on the like what would be whites of the egg, but now have turned kind of translucent.

Yes. So we got some special ones. So what happens is the duck eggs, they get covered in this paste of lime, which is calcium oxide or calcium hydroxide, which is a very basic chemical. It's like super high in pH. And that pH contributes to this color change and then the additional salt in the solution helps preserve it. That is actually my best guess for how they get their name Skin Egg P done. And so the thing about cooking is it's really about changing protein structure. And proteins naturally as they're in living eggs or humans come in a very specific shape to do their job. When we cook them, we unfold them, which is a process called denaturing. And you can do that in a number of different ways. You can do that by heating them, which is what we normally call cooking.

You can do that by changing the pH because it disrupts their three-dimensional structure. And you can do that by adding salt. So this P-Dun has really been altered both by being placed in a high pH environment and a high-salt environment. So let's talk about. So let's talk about salt substitutes. Sure. Earlier, we talked about how too much salt is not great for our bodies,

so people often use salt substitutes when they're trying to cut back on sodium. It looks like table salt, but it's a bit smaller than table salt almost. Oh, my God.

How does it taste to you? Oh, it's weird. It feels wrong. Mm-hmm. Like, it feels like butter is to margarine or margarine is to butter. It's like salt-ish. It feels like it's hitting receptors

that aren't quite salt receptors. It feels like it's hitting different ones, but it still kind of tastes like salt. It's super weird. Yeah, so you've described exactly what happens. It hits both your salt receptors and some others, and if you have a lot of it, it begins to taste a little bit more bitter.

Salt substitute, the kind that we're both having, is potassium chloride. And potassium, if you think about our friend the periodic table of elements, which is the ingredient list, of the universe, all the way on the left, that first column, the alkali metals, that's where sodium lives, and that's what we've been talking about up to this point. Now, the tables organized to tell us a little bit about how these elements interact, and just below sodium is potassium.

And because they're in the same column, they tend to have some similar properties and some different properties. And one of the similar properties that they have is potassium ions will trigger our taste receptors that signal our brain something is salty. So that is happening. Other receptors are also getting triggered, which is why you had the reaction that you had. It's like salt and then other stuff. And again, whereas we tend to be totally covered in our sodium intake, many people do not get enough potassium. So potassium as a substitute for salt really could benefit you health-wise by reducing your sodium intake and increasing your potassium intake. But the flavor is not quite the same. And so people use salt substitute carefully,

basically. So what excites you about salt? Like, what makes it special to you? Well, it's not just essential for life. It's really essential for taste. I mean, the reason it's so present in our diet is it's such an enhancer of food. flavor, right? Some people add salt to desserts because it actually amplifies the tastes of everything else. I think it's kind of unique to think about in that almost everything else we eat is organic, right? Organic in the chemistry term, in that it was derived from plants or animals or microbes. And salt is this inorganic thing. It's just this mineral, this rock that is such a major component of our food and our taste and what we consider delicious.

Thank you, Dr. You, Julie, for taking time to talk to us about salt. I learned a ton and I learned that I actually like a thousand-year-old eggs. Thank you so much for having me. I love to eat and would love to chop it up anytime you're hungry again. This episode was produced by Thomas Liu, edited by Rebecca Ramirez, and fact-checked by Catherine Seifer. Giselle Grayson is our senior supervising editor. Neil Carruth is our senior director of On Demand News Programming.

And Anya Grunman is our senior vice president of programming. I'm Emily Kwong. And I'm Regina Barber. Thank you for listening to Shortwave, the Daily Science Podcast from NPR.