Science Friday - Mosquitos and Smell, Fermentation, Model Rocket Launch. July 12, 2019, Part 2

Episode Date: July 12, 2019

If you’ve ever tried brewing your own beer or raising your own sourdough, then you know that the process of fermentation isn't easy to get right. How do you control the growth of mold, yeast, or bacteria such that it creates a savory and delicious new flavor, and not a putrid mess on your kitchen counter? David Zilber is Director of Fermentation at the restaurant Noma, and he tells his fermentation secrets. The human scent is made up of a combination of 100 odor compounds. Other mammals such as guinea pigs also emit the same odor compounds—just in different blends. And even though human odor can also differ from person to person, mosquitoes can still distinguish the scent of a human from other mammals. We'll talk about how mosquitos have evolved to hunt for the prey of their choice. Next week marks the 50th anniversary of the Apollo moon landing. But before astronauts could take that one small step on the moon, they had to take off from Earth. On Tuesday, July 16, in commemoration of the 9:32 am launch of the Saturn V rocket carrying the Apollo 11 crew, model rocketeers from around the world will conduct a global launch event—by firing off thousands of rockets planet-wide. Plus, download the SciFri VoxPop app for iPhone or Android and contribute to the show all week long. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. A bit later in the hour, we'll be talking with a world-class fermentation expert about experimenting in your home kitchen. What's the weirdest thing you've ever eaten fermented? How do they taste? Call us and tell us. Our number is 844-8255-844-Sy-Talk or tweet us at a sci-fry. But first, did you know that the human scent is made up of a combination? of a hundred different odor molecules.

Not only are they produced by a person, but some are from their microbiome. These molecules aren't unique to humans. Other mammals such as guinea pigs also release the same ones, just in different blends. And even though human odor can also differ from person to person, mosquitoes can still distinguish the scent of one human

or a human from other mammals. My next guest is going to tell us how mosquitoes have learned to sniff us out. Dr. Carolyn Lindy McBride, an assistant professor at Princeton University. Welcome to Science Friday. Thanks, Ira. It's so fun to be here. That's nice to have you. We're all familiar with the mosquitoes that bite us every summer, but how many types of mosquitoes are there out there?

Yeah, they're at least over 3,000 species. There are a lot of different types of mosquitoes out there. And how many of them actually drink human blood? Well, a lot of them will bite humans. Yeah. But what's really interesting to me is there are a few species that really specifically look for humans. They really specialize in biting humans.

That's rare. And your study looks at how mosquitoes differentiate between humans and guinea pigs. What a combination. That's right. Yeah. A lot of people ask why guinea pigs. Honestly, they're practically easy. They're docile.

They're small. They fit in our olfactometer, it's called, the box we use to test mosquito preference. And so we use them as a representative of many different non-human animals. We always check to make sure our results aren't just about guinea pigs. They're more about humans versus any non-human, but guinea pig is sort of our workhorse. Okay, so how are guinea pigs? How are mosquitoes so good at finding humans? So mosquitoes use a lot of different cues to find humans, not just odor, but also our body heat, they respond to visual cues, really importantly, the CO2 in our breath.

But the way that they make choices between different species, I mean, all worm-blooded animals at least give off body heat, and all animals in general give off CO2. So it's the specific body odors that help them really differentiate between different species of animals. So it's true, we give off 100 different odors? Yeah, there are, you know, hundreds of compounds in our odor. Not all of them are highly volatile. Many of them are in very small quantities, but it's extremely complex. So a mosquito sniffes the odors and then decides which one it's going to have a meal with? Yeah, that's right.

Most people think the first thing that they detect is CO2, that kind of sensitizes them to other, other cues. And then they catch a whiff of human, at least these mosquitoes that we study, and they'll start flying in that direction. And how much does human odor differ from, say, a guinea pig's odor? Yeah. Animals tend to give off the same types of compounds. Not every human odorant will be in guinea pig odor, but it'll be found somewhere in the animal kingdom, the odor of some animal. And most of the compounds are shared. And how different is the odor from one person to another person? Yeah, there's variability there too. But the variability between humans is less than the difference between a human and non-human. But there are differently differences between

humans and humans are differently attractive to mosquitoes. How do you collect the human odor when you do your research? Yeah. We take a follow-to-product by some colleagues in Sweden, but we do a full human body odor extraction is what we call it. We recruit volunteers, and we ask them to undress and crawl into a big oven bag with their head sticking out. It's sort of cinched around their neck. And they lie in this bag for two hours. They can watch a movie of their choice. And we basically introduce clean air into the bag. And then it sort of feels like a gentle breeze. The air is moving really slowly. It exits the bag through eight different holes. And it has to pass through a small filter that traps all the odor. And so you trap the odor and then you

you feed it to the, I guess, to the mosquitoes? Yeah, well, exactly. We use it for all different types of things. For behavioral experiments, we use it in neural imaging experiments. We analyze it. Do all sorts of things with it. Is there one kind of odor that's more prevalent in humans than any other? Yeah, definitely, I can think off top of my head of two compounds that are particularly

abundant in human odor relative to animal odor. One is a compound called lactic acid. And in fact, lactic acid is the only compound I know of that is slightly attractive to mosquitoes on its own, to these mosquitoes. Another is a compound called sulkatone. It's a ketone, and it's not attractive on its own to mosquitoes. And so I know that our skins, our bodies that compose trillions of, you know, microbes. We have a whole big microbiome. How much of our odor comes from our microbiome. Yeah, a lot of it. There have been some sort of seminal experiments that show that sweat on its own is slightly attractive,

but sweat that's been incubated on human skin with human microbiome is very attractive. So I don't think we know precisely how much of human odor is from the microbiome, but it's very clear that they do something to our odor that makes it very attractive. Do the people who make mosquito repellent know all about this stuff? Yeah, people who study this, many of those people are aimed at designing repellents or attractants that can pull mosquitoes into lethal traps. Absolutely. What about Deeth? Why does Deet work so well?

Well, that is very controversial, and it's not something that my group has directly studied, but there are a few different theories. One is that Diet sort of scrambles the olfactory code. So a mosquito's flying along. It's like, oh, there's a human, and all of a sudden, Diet is there, and it changes the way all of the neurons in its brain respond to human odor, and suddenly the mosquito can't smell the human anymore. So you look at the brains of mosquitoes? Yeah.

We do. What did they tell you about scent perception? Yeah, well, we'd like to understand exactly how their brains have evolved to make them so good. But again, we're just talking about 80s egypti. That's one species of mosquito that really specifically targets humans. And we want to know exactly how its brain has changed that allows it to be so sensitive to the way we smell. So we make transgenic mosquitoes that express calcium sensors and neurons, and then we can cut a little window in the head and mount them under a big microscope,

and we can basically see the neurons responding to human odor. You know, you always hear some people saying, you know, I get bitten by mosquitoes so much more than other people. Is that true or is just that perception? Well, it's definitely true that different people attract different numbers of mosquitoes. But what's interesting is that most of people's perception of how attractive they are is really driven by how strongly they react to bites. And if you think about it in an extreme case, a postdoc in my lab, her husband absolutely does not react to mosquito bites. And so he never knows he's getting bitten. He may actually be quite attractive.

And someone who reacts strongly remembers every single bite. That is quite interesting. So people may not even realize because they don't react strongly that they are even bitten by mosquitoes. That's right. That's right. And so that drives people's perceptions, but it is true that some people are more attractive than others. Would using, let's say, perfume mask, smell, so the mosquito stays away? Yeah.

You know, this is like finding a human and getting blood is so important to a mosquito. They are very good at this. It's, you know, whether you use lotion or perfume, There are very few compounds that people have found that actually repel them or prevent them from finding you. So, no, like some random perfume off the shelf is really not going to help. With most scientists studying insects, they're either trying to protect them or kill them, right? Why were you interested in studying mosquitoes? Were the protection or the killing side?

I was actually neither. I was really interested in how insects evolve and how they adapt to the things that they eat. And I used to study butterflies adapting to different host plants. And then I heard about this mosquito, and I just thought it was so fascinating how it's evolved to specialize in essentially eating humans. And also it's so easy to rear in the lab. There are all of these genetic tools that are available in the species. So actually the idea of getting rid of them or preventing them from biting humans was an afterthought initially, although now it's an important part of what motivates us. You're also looking at odors for other animals.

What do you hope to learn from that? Yeah, there haven't been. A lot of people have analyzed human odor, and you'll see studies here and there on the odor of some various animals. But there haven't been really comprehensive studies of how exactly human odor is unique. Like just statistically speaking, what would be the most efficient or logical way to reliably find humans? And for that, we really need to describe what we call as host odor space, the odor of all the different potential hosts a mosquito mite bite. How many odies do you think there are in total? Thousands?

Oh, geez. Oh, yeah. My chemistry is actually quite poor, but yes, thousands, absolutely, odorants. I mean, there's hundreds of thousands of compounds, right, or millions, but not all of them can be smelled. Not all of them are volatile. Have you ever looked into it? I thought about looking into changing our odor by maybe what we eat?

I haven't looked into that myself. You know, you hear old wives' tales sort of about if you eat bananas. you'll be less attractive to mosquitoes. If you eat a lot of garlic, maybe you'll be less attractive. There haven't been big well-designed studies to test those things. I'm personally dubious. What would you like to study the most? If I had a blank check and I sometimes ask people, what would you do with it?

What would you like to do that you can't do now? Well, I mean, I guess I'm in a lucky position of saying that we are doing the things we really want to do. And that is understand exactly how the neural circuits in the brain of these mosquitoes have evolved. Understand where this preference for humans evolved. We have one project that's looking, collecting mosquitoes and testing their preference in various parts of Africa to understand exactly what were the initial sort of drivers that caused the species to specialize in biting humans. And also, yeah. Yeah. So, wow, why do they want to buy humans?

I hope you find out and come back and tell us, okay? Yeah, we'll try. All right, Dr. Carolyn, Lyndie McBride, assistant professor at Princeton University. We're going to take a break on when we come back. A world-class fermentation expert demystifies the world of bruise and ferments. Call us with your home fermentation questions. Do you try to ferment stuff at home? It doesn't work?

Well, we're going to try to help you out. 844-8255-8-4-6-4-Sight-Talk. You can also tweet us at SciFri. I'm also going to try out of a couple of... of a kombucha formulations here and we'll let you be the job, I'll be the judge on this one. We'll be right back after the break.

This is Science Friday. I'm Ira Flato. If you've ever tried brewing beer at home or baking your own sour dough or pickling cucumbers, then you are familiar with the process of fermentation. And you know that it's not so easy to get it

right. How do you control the growth of mold or yeast or bacteria such that creates a savory and delicious new flavor and not a putrid mess on your kitchen counter, right? Takes a little bit of trial and error, a little bit of luck, and a little help from some culinary experts. And that's whom we have with us today. We want to know what is the strangest thing you've ever tried to ferment at home, and how did it go for you? If you have a story about fermentation fail, something that didn't work, something that worked great.

We'll like to hear that, too. give us a call our number 844-724-825-8-8-4-Sai Talk or tweet us at SciFri. One of the reasons I'm asking is that NOMA restaurant currently rated number two in the world has distinguished itself as a creative leader in fermented dishes, experimenting with things like lacto-fermented fruits and vegetables, and they've written down what they've learned in a new book, the NOMA Guide to Fermentation, David Zilbert. director of fermentation at Noma Restaurant and author of the book,

The Noma Guide to Fermentation is here. David, welcome to Science Friday. Hi, thanks for having me. There's a photograph of a guy doing all this stuff in the book. I'm imagining, is that you? That is me, yes. Seems like you're having a lot of fun with this. Yeah, I mean, the photo shoots to make the book were a lot of fun.

because we had to make everything like three or four times for three or four times over. How did you get interested in fermentation? Well, you know, I've been cooking in professional kind of high-end kitchens for probably about 15 years, and the first restaurant I ever worked in

was an Asian restaurant, and we did make our own kimchi. There were only cooked with lots of really amazing soy sauces imported from Japan, but I never really gave it second thought that these were anything more than just ingredients that you would grab off the shelf. But when I got to Noma in 2014, the chef of the restaurant, my boss, Renee Red Zeppi, kind of noticed that I had a knack for science.

People would just ask general questions. So, like, why isn't this cabbage the same as it was yesterday? How come the bone marrow isn't roasting just as well as it was last week? And I was usually the guy with a far too detailed answer. And I think he caught on that I had a knack for the sciences, and then he moved me into the fermentation lab. And I took over the reins after a couple years. Well, you certainly have a geeky knack for it, because you explain it all very, very well, and you certainly enjoy it. So there is a lot of science and chemistry going into fermentation.

There is. But I will preface that statement and say that, you know, everything is science and chemistry if you look closely enough. Yeah, well, that's true. So let's talk about what's going on. What is going on in the fermentation process that makes, you start out with something and you wind up with something else, right? What's going on there? Yes, that's exactly it. Well, the most succinct way that I could define fermentation in layman's terms is that it's the transformation of one ingredient into another by way of a microbe.

So if you imagine that you start out with cabbage and then you get lactic acid bacteria to grow in and alongside your cabbage, in two or three weeks time, you end up with sauerkraut. It's not the same as it was going in. You've cultivated, cultured, really, this microorganism in your container with your cabbage. And lo and behold, a transformation's taken place. Well, for some people, though, the transformation just turns into rotten food. This is true. So where is the fine line?

And you say there is a fine line between rot and fermentation, and then you make the analogy of an actual line outside of a nightclub. Yeah, yeah. And the rest of the analogy is that as a fermenter, you know, there's actually three people in play in the definition of fermentation. The ingredients, the vegetables, or the food stuff, the microbes, but also the person who's acting on that situation and actually willing the ferment into existence. So as a fermenter, you're kind of like the bouncer outside of a nightclub.

You're the guy with the velvet rope, the big, the big mussely dude. And you're the one deciding who gets into the club and makes a great evening where everyone's sipping champagne and beautiful people all around. And all the drunkards and rowdy boys stay outside. So that velvet rope that you use as a fermenter, those are all sorts of control points, you know, whether that be salt or access to oxygen or temperature or pH and acidity levels, these are all things that you have at your disposal as a fermenter to make sure that you're actually fermenting and not rotting. Rots a club where everyone gets in. Fermentation is one where the party's popping. Interesting. Let's talk about lactic acid bacteria.

and lactate acid fermentation. Take us through that. Well, fermentation, it's one of the simplest fermentation you could undertake. By adding a little bit of salt to, let's say we're taking a very simple ferment, like sauerkraut. You have your cabbage, you shred it to rupture the cabbage cells, and it makes it easy, for bacteria to get inside there. Now, lactic acid bacteria are all around us. They live on your skin.

They're on the fruits of vegetables. They're on the skins of fruits and vegetables. They're basically ever present in our environment. And as you add salt to that shredded cabbage, you're making sure that any malevolent microbes, things that might cause the mixture to rot, are kept at bay. Salt is a really great,

antimicrobial, but lactic acid bacteria have a little bit of resistance to it. They can tolerate salt up to a certain point. So you kind of clear the playing field for lactic acid bacteria to do their thing. They start consuming the carbohydrates and sugars in that cabbage, and in doing so, they leave something else behind. That's something else is an exclusionary chemical. That's lactic acid. It sours the mixture, and then makes it even harder for different things to grow. And over time, that fermentation process peters out. They consume as much sugar as they can. The pH drops because of all of the lactic acid they've produced, and you have sour cabbage, literally translated from German sourcrow. Interesting. I want to ask you a question that you ask yourself in the book, and what is it

about cabbage that lends itself so well to fermentation? You know, that's a very good question. It comes up time and again in independent centers of agricultural production, but you go back through history and you know the Koreans were doing it with kimchi and people have been doing it in Europe for hundreds of years. I think it is one of these hardy vegetables that's harvested, you know, in the late summer and fall. That was neither too sweet nor not sweet enough to ferment and it just, it keeps really well. So it made sense that people would make sauerkraut or kimchi, sour cabbage in any form,

to have food for harsher times for winters and things like that. Right. A tweet from Maggie, he says, what's the difference between pickled and fermented? So, any way you break it down, a pickled product is fermented. Now, there's two routes to pickling. You can either do a quick pickle, which is making vinegar and then, you know, boiling your vinegar with a bit of salt and sugar and spices and then pouring that over your

vegetables. or you can sour your vegetables into a pickle. Now, the difference is that there's two different acids that play in there. With a quick pickle, with a vinegar pickle, you're using acetic acid. But with a sour pickle, you're using lactic acid. So a vinegar pickle, you have to first make the vinegar, and that is the sugars of fruits first transformed into alcohol by yeast. And then another fermentation process happens.

You have acetic acid bacteria, another ever-present bacteria that's floating on dust, in the air that'll settle into an open bottle of wine and eventually sour it into vinegar. That gets poured over your vegetables, whether that's carrots or radishes or cucumbers, and the pH drops so much so that it's effectively preserved. Lactic acid fermentation, the sour pickle, that's the process I just described with sauerkraut, and you're getting it all to happen at once. You're getting those bacteria to grow in and around the vegetable you're looking to ferment, and it sours the brine.

sours the plant matter itself. And in one shot, you have a pickle that you can keep in your fridge for months. Yeah, I do that with my pickles. They last for a long time. Let's go to the phones. Kathy in Orlando. Hi, Kathy. Hi, Kathy. Hi, Kathy. Hi, Kathy. Hello. Hi, go ahead. Hi, go ahead. Hi, hello. Hello. This is Kathy. Go ahead, Kathy. Can you hear me? I sure can. Hey, we would make several crocks of sauerkraut in the fall, and the house either smelled wonderful or horrible, depending on how much you like sauerkraut.

But it was so much fun every day going down and snitching a little bit to see how the taste was different every single day. That's good. And then later on, when I read, have learned about kimchi. I thought, well, I could do that. I just got some of the Korean hot pepper sauce or hot pepper spice and made that. And that was good. My friends that are Asian, a lot of them have a separate refrigerator so that it doesn't make everything in the refrigerator smell like kimchi. And you, thank you for that call. And you talked, David,

in your book about actually creating a homemade place to, to do the ferment. Yeah, you can absolutely build fermentation chambers, or you could even, you know, if you have the space, you can make a little cellar. I mean, Korean grandmothers in South Korea, you know, they have urns that they just bury into the soil in their backyard, and actually helps to mediate the temperature

to make sure that their cabbage doesn't get too hot during the winters and stays nice and cool. But in building a fermentation chamber or a cellar or any place to really ferment, I mean, at Noma, we have a lab, but it could just be a closet. What you're really trying to do is create an environment. Just like there's penguins in the Antarctic and Birds of Paradise in the tropics, every type of bacteria has an environment that's best suited for its life to thrive. And as the fermenter, it's really your job to try and make that environment as well.

well suited to the microbe you're trying to cultivate in whatever food you're trying to ferment. Here's a tweet that came in it says, does fermentation always produce alcohol as a bi-product? No, it does not. There are many different types of fermentation, and some types of fermentation have nothing to do with alcohol at all. Now, a biochemist might say, technically that's wrong, because the very strict textbook definition of fermentation is the transformation of glucose into ethanol.

in an enzymatic pathway by yeast. But in the real world, in the much broader sense, as I said, there's all sorts of different metabolites or byproducts that you end up with in fermentation. Sometimes it's sugar. Sometimes it is MSG or the actual flavor of umami. Sometimes it's alcohol. Other times it's acids.

So there's a whole flight of different end products in the world of fermentation. And the more you understand it, the more you can actually kind of paint with these flavors, and really tweak the world of food to your will. I'm Ira Flato. This is Science Friday from WNYC Studios. Talking with David Zilber, author of the Noma Guide to Fermentation. He is also Director of Fermentation at the Noma Restaurant in Copenhagen.

One of these beautifully illustrated book, and one of the things I love about it is that you don't take for granted that people know how to follow instructions. actually have very detailed photos to show us how to do it correctly. Yeah. And that's important because, you know, you can read a recipe. Someone might talk about an experience they've had anecdotally, but there is something to actually, you know,

seeing the texture of something, seeing how much pressure you need to squish a pee between your fingers to know that it's perfectly done. And that's something that we didn't want to skimp on. We wanted people to be able to ferment successfully because there is a lot of, you know, hazy, there are a lot of hazy definitions out there and kind of folklore around this topic. And we just wanted to kind of clear the air and say, oh, this is how you can do it really well and really easily.

Let's go to Patrick and San Francisco. Welcome to Science Friday. Hi, there, Patrick. Hi. Hi, how are you guys? Hello. Thanks for taking my call. First off, David, a big fan of your book.

Absolutely love it. I was here in San Francisco when you guys debuted. it. It's really amazing what you've done there. So thank you for that. And congrats on number two, best restaurant in the world. That's a huge achievement. Patrick, I'm running out of time here. See you got up with a question. Sorry, sorry. I guess two questions. One is, what are you most excited about in fermentation? Are you guys going deeper into lacto fermentation or any of those avenues that you've discovered or described in the book? Or is there a new type of fermentation that you're venturing into.

And then the second question is, as a citizen food scientist, what recommendations do you have for somebody who is venturing into fermentation and going deep? What recommendations do you have for somebody like myself? Let's work backwards on that one. What about the novice? What's the best way to start? For the novice, start with the things you like eating. Before you try and make something that you've never really had before, before you

try and get into the first half of the process of making soy sauce. Start with something that you really like eating. If you love pickles on your hot dogs, make pickles for the first time. It's really that easy. It's something you can do on your kitchen counter and you can watch it happen before your eyes. For someone, for a citizen scientist who wants to go a little bit deeper, I think it's really fun to take up craft brewing and really try and understand the world of yeast, of which there are like tens of thousands of different varieties that all have these different

flavor profiles. And the coolest thing about fermenting at home and really getting into it and getting really nerdy with it is that you almost get to taste places on earth in your own garage or in your own apartment. You can get yeast from Belgium and taste a piece of history because these yeast have been cultivated in the rafters of abbees that the Belgian monks are famed for making their beers in. So it is really cool to get very nerdy. and go really deep and taste the whole pantheon of flavors

that the microbial world produces. And as for your first question about what I'm really excited about, to be honest, I'm really excited about the thing I haven't found yet. There's a lot of things that people in the world of fermentation know really well. That's because all of these ferments that we consume on the regular, whether it's chocolate or coffee or pickles or wine, these are all very traditional products

that have been passed down through generations for hundreds of years. That's why we still make them today. But in the same way that that makes fermentation amazing, I also think about the way pharmaceutical companies send out teams of scientists into the Amazon jungle to find a rare type of mushroom that might produce some sort of miracle drug that will change the face of the pharmaceutical industry. I wish there was someone like that in the world of fermentation, looking for that rare microbes that would produce a flavor that no one's ever tasted yet.

Well, they better know what they're doing. We're going to come back with David Zilber, author of the Noma Guide, to fermentation right after this break. Stay with us. This is Science Friday. I'm Ira Flato. We've been talking about the magic of fermentation and experimenting with it in your home kitchen with my guest, David Zilber, director of fermentation at Noma Restaurant in Copenhagen,

and he's co-author of the new book, Great Book, The Noma Guide to Fermentation. Our number 844724-8255. And we have been taking questions not only online, but we've been taking questions. not only online, but we also have a new app called the SciFRI Vox Pop. And you can join in the conversation for searching. You can search for that app. You can join in. Get it's CyFri V-V-V-V-V-T-R-V-T-O-X-P-P-P-P, and you can download that and leave

us a question. As a listener from Japan did, and he had this to say about kombucha. I'm Nobu from Japan. kombucha is very familiar among Japanese. It's very useful, not only drink, but also to use a lot of cooking. We often eat natto-fremated soybeans. It's very sticky. What exactly is kombucha, David?

I have a little... I actually have a little bit of it here in a cup, which smells a little vinegar. What is it? Yeah. kombucha is a sweet and sour microbial tonic, I guess you could call it. But folklore goes back to an ancient Korean physician that would travel around Asia. Again, I don't even know where, when in history this would have taken place. But that this physician would brew this drink and, you know, kind of heal people with it.

kombucha is basically sweetened tea that is then fermented in a symbiotic way by yeast, which converts the sugar into alcohol, and then acetic acid bacteria that convert that alcohol immediately into acetic acid, the acid that you taste in vinegar, like white vinegar. Now, if you drink kombucha and you buy it off the store shelf, sometimes you might taste really vinegar, and that's probably because, well, In my opinion, it's over-fermented. The thing that you have to understand about fermentation is that fermentation is cooking. It's just cooking that happens much more slowly.

So just in the same way that you can overcook a piece of chicken by roasting it in a pan for too long, you can also over-fermint something like a kombucha and make it too sour by letting it just ride out on your kitchen counter for three weeks instead of two. And sometimes if you taste kombucha and you're like, oh, this is a little hard to get down. try making it yourself with some of the guidelines in the book. And you might find that it's actually really, really pleasant to drink. I'm going to try. We make coffee kombucha. Yeah, that's the one I saw.

I want to try that one. Coffee kombucha. It's so good. Mm. Yeah. Summertime drink? We serve it to our guests in the summer as a chilled kind of after coffee drink for the meal. And people love it.

I drink it every day instead of hot coffee in the restaurant. I'm a little addicted to it. it. The kombucha bottle it says organic and raw probiotics, it's good for you. Are there live probiotics in kombucha? There

are. There can be. A kombucha can be pasteurized, just like you know, milk can be pasteurized or canned goods can be pasteurized. You can heat it and kill

everything in it and not really affect the taste that much. If they say that there are live cultures in it, it means that it was fermented and nothing was really done to it after it was put into a bottle. Now, there's a lot of conflicting information about kombuch out there, and I've read a lot of pretty hardcore studies that say, well, a lot of this is a bit bunk. But at the end of the day, I'd probably say that drinking kombuch is better for you than drinking a can of Coca-Cola.

So, you know. Let me go to the phones, because there are so many people before we run out of time. Let me take a couple of calls. I'm going to go to Robert in Cleveland. Hi, Robert. Hello. Hi there. How are you?

Go ahead. Hi. A couple questions real quick here. I've made sauerkraut, and sometimes I've made sauerkraut with some other vegetables mixed in. And what I would do is I put it in a large jar and put a big cabbage leaf on the top and a stone on top of that to hold it down below the brine. And, you know, sometimes I'd get a significant amount of mold on top of that, which I would just, you know, take that top leaf off and throw it away with the mold.

and other times not so much. And I'm just wondering, is the variable, the temperature that it's sitting around in? Usually it's in room temperature for a couple of weeks. And also just fermented foods in general, are they really good for you? Or is that just how they used to preserve food? And we just keep doing it. Good questions. Yeah.

Yeah, as for the mold question, now that is something that you're constantly trying to fight back when you're trying to ferment, especially lacto ferment in something like a crock. There are so many variables that go into making a successful ferment. How clean was your vessel before you put the food in there? How clean were your hands or your utensils? How much salt did you use? How old was the cabbage you were even trying to ferment in the first place? every little detail is basically another, you know, variable in the equation that leads to a fermented product being amazing or terrible. And it is a little bit like chaos three.

It's a little bit like a butterfly flapping its wings in Thailand and causing a tornado in Ohio. But with lots of practice, you'll begin to understand that, okay, if it was, you know, 30 degrees that day, maybe things were getting a little bit too active. Maybe the fermentation was happening a little bit too quickly. Maybe I opened it, you know, a couple times more than I should have, and it was open to the air instead of being covered. So there's lots of variables. But I would say that if you're having a lot of trouble with mold, just up the salt percentage by a couple percent.

It'll make for a slightly saltier sourcrow, but it'll actually help to keep those microbes at bay. You talk about something called Koji in your work. You say we find Koji indistinguishable from magic. To experience Koji's brilliance for yourself, you simply need to pop some in your mouth and taste it. What is Koji? And why do I need to have it? It's the biggest microbe you've never heard of.

Koji is responsible for everything tasty that comes out of East Asia. From China to Korea, to Vietnam, to especially Japan. It is a mold, a helpful mold called a... Aspergillus Orizi. It is responsible for turning the starches in rice and barley and all sorts of grains into sugar and turning the proteins in those same grains into the flavor of umami. It's responsible for soy sauce, for sake, for rice wine vinegar, for miso, and it can be used in all sorts of novel and inventive ways as well. But you never see it as the finished product because it usually is kind of the first step in that process.

I'd liken it to the step of malting barley when you make beer or whiskey. That's basically how ancient Asian civilizations came about that process of turning grains into something sweet that you could then ferment with yeast. They found a mold instead of finding the process of malting, and it is absolutely remarkable for the flavors that it brings to the table itself. All right. Tell me how I would get it or make it, or what would be a good way to start. Well, there's a line that I say when people always ask, like, where can I, where, how do I just start growing Koji?

All life comes from life. All cells come from cells. At the end of the day, you know, everything living on Earth today has been an unbroken chain of succession for three and a half billion years. And Koji's no exception. You know, if your kid wants a golden retriever puppy for Christmas, you have to go and find a golden retriever mom. And it's the same for Koji. You're going to have to find a Koji breeder and actually get some sort of. spores from them. We buy ours from a laboratory in Japan, and we have it shipped over to Copenhagen.

But that's one of the funest parts about fermenting, is that once you start making fermenter friends, people are just sharing cultures and having a good time, and you get to taste a little bit of someplace else. And you have to keep the cultures alive, or else they'll die out? Koji can actually, Koji can coast for a while. When you throw it into its next generation, When you get it to produce basically offspring in the form of spores, those spores can actually be stable for six months to a year, or even longer in the freezer. So once you produce the spores, you can hold on to them

and then just keep them on hand and then make your actual cozy by growing this mold on your barley or on your rice whenever you see fit. And it grows pretty quickly, too. It only takes 48 hours to completely do its job. So you can get cozy with your cogi. You know, we actually tuck ours in with a blanket at Noma, so yeah, we do get cozy with Goji. I can't top that, and we run out of time. David Zilbert, Director of Fermentation at Noma Restaurant in Copenhagen.

And if you want to see all these great recipes and well illustrated, it's a wonderful big book, it's the Noma Guide to Fermentation. It starts out with the really simple. You can just ferment some plums or blueberries. It goes up all the way up to Kogi and other kinds of stuff. It's a terrific book. Thank you, David, for taking time to be with us today. Thank you so much for having me.

People are looking ahead to next week's big anniversary of the Apollo 11 mission, 50 years since that one small step on the moon. But, you know, before you can step on the moon, you have to step off of the Earth. And that's why next Tuesday, people around the world will be celebrating another anniversary, and that is the anniversary of the launch of the Saturn 5 rocket, Canada. the Apollo 11 crew. And how better to celebrate one rocket launch than with another, or 5,000 of them, all at once. Joining me to talk about it is Dr. Deborah Barnard, director of the U.S. Space and Rocket Center in Huntsville, Alabama. Also, the Rocket City. Welcome.

Hi, Ira. Welcome. Happy 50th anniversary, Apollo 11. Well, thank you very much. When we were out there, Charles Berkowitz, our director was actually actually practicing launching one of those rockets. Everybody needs to launch a rocket, especially this coming launch day, Tuesday, the 16th. All right. Give us the event and the plan. So here's the deal. Huntsville is the Rocket City, and of course it's home to Space Camp.

And every day we launch rockets at Space Camp. So we thought, what better way to celebrate the landing of mankind on the moon than to have people around the world launch rockets? We thought we would kick that off here at Space Camp by setting a Guinness World Record to launch 5,000. and rockets simultaneously from one place at one time. And how many people around the world do you hope do it at the same time? Well, immediately following our Guinness record, we are asking all of our almost one million space camp alumni and anybody who wants to join us, museums, schools, Boy Scouts, Girl Scouts, churches, anyone, to grab a rocket and launch it with us.

And we'll also set a global rocket launch record for the world in that 20, 24-hour period. Looks like so far, Ira, we're going to have about 80,000 participants from around the world. 80,000 launching at the same time or whenever they want to? Well, we're going to launch 5,000 at one time in Huntsville to kick it off at 832 a.m. in celebration and honor of Apollo 11, and then those 80,000 people will launch them around the clock in their own time zones during the next 24 hours. Wow. Okay. So let's say you don't know anything about model. rocketry, is there still time to get ready for Tuesday? Shoot, yes. This is easy.

We're going to be launching rockets that have little engines, SD's Pathfinder, 15-engine rockets. But anyone can launch any kind of rocket. There's stomp rockets, bottle rockets, green rockets, air rockets. And our website has all of those things from NASA about how to launch water rockets and all different kinds of rockets that almost anyone can do almost anywhere. So you can go into one of the, you can go one of these stores, a hobby store, and buy yourself a rocket kit if you don't have one. You absolutely can. You absolutely can. It's never too late to do it. You can go to rocket center.com slash global rocket launch,

and all the different kinds of rockets that you can launch are listed there, and there are ones you can make for yourself at home. Right. So let's say I want to do it at the same time you guys over there in Huntsville are doing it. Is there a website I can go on and actually press the button at the same time you're pressing, your buttons over there? No, not exactly, but if you do sign up at rocket center.com slash global rocket launch and share it on social media, then we'll count you as part of the global rocket launch record, and we will send you a certificate. If we can get your social post at hashtag global rocket launch, we'll count you in the numbers, and you can be part of setting a world record. And are the Guinness book people involved in this to certify this?

Oh, yes. Yeah? Absolutely. The rocket launch from here in Huntsville, the 5,000 that we'll do to start it off, will be certified. We'll apply for Guinness certification. And in order to do that, Guinness requires that the type of rocket that we're launching be commercially available, which it is, that we will surpass 100 feet of height with our launch. And, of course, we have to have independent judges.

And we have about the best judges in the world because we have more rocket scientists per square inch in Huntsville, Alabama. the rocket city than anywhere else on the planet. And where, how are you collecting your 5,000 participants? We have them already pre-made. We've had people working for weeks in the evenings and on Saturdays, building and constructing the rockets, and we have them all laid out. It's kind of cool.

We've got them laid out to look in five different engine shapes, just like the original Saturn 5 F1 engines. So they're all set. They'll go on grids. They'll start with an electronic starter. We're not using matches on 5,000 rockets at once, and they'll all go at one time with the flip of a switch and the press of a button. And where is exactly what spot will you be launching them from? We will be launching them from the Space Camp rocket launch pads on the premises at one Tranquility Bay, Huntsville, Alabama, U.S. Space and Rocket Center, home of space camp.

Are these mostly kids in space camp who are assembling them and launching them? We've had actually a lot of volunteers from the aerospace companies in Huntsville. We've had Northrop Grumman and Boeing and Lockheed and all kinds of actual aerospace engineers who just wanted to be kids and come over and help us build a rocket. All right. Give us the exact time and date where this will happen. The exact time and date will be Tuesday, the 16th of July, at 832 a.m. Central Time. That's the Guinness World Record launch.

but anyone can launch a rocket any time during the 24-hour period of Tuesday the 16th. And if they'll register or go on social for global rocket launch, then we'll count them in the world record, and we'll send them a certificate of thanks. Thank you very much, Dr. Barnard, and good luck to all you folks. Ira, come on back to the Rocket City, and happy Apollo 1150th to everyone. Same to you. Dr. Deborah Barnard is the director and CEO of the U.S. Space and Rocket Center in Huntsville. And next week we'll be airing two full hours and tripped to Apollo, taking a look at the scientific and technological legacy,

taking you on a field trip to some of the historic launch sites at the Cape and talking about the next generation of rockets to bring us to the moon. So we want you to tune in for that next week. And if you've wondered what it's like to fly with bats or to slip on a hazmat suit and work with some of the world's most dangerous diseases, if you're in Texas, come on down, come on out, come to see Science Friday Live when we bring the show to the Tobin Center

for the Performing Arts Saturday August 10th in San Antonio. Yeah, Saturday August 10th, San Antonio. We'll talk with local scientists about bats, birds, biohazards. You can get more information on our website at science friday.com slash San Antonio. Come on out to see Science Friday, Saturday night, August 10th.

In the meantime, have a great weekend. We'll see you next. week, I'm Ira Flato in New York.