This is a transcript of the Gastropod episode The Birth of Cool: How Refrigeration Changed Everything, first released on June 11, 2024. It is provided as a courtesy and may contain errors.

CYNTHIA GRABER: So I’d like to start with the easiest question, and that’s if, [LAUGHTER] you could say your name and, you know, to make sure I pronounce it correctly and also how you’d like to be identified, like the host of what or the author of what?

NICOLA TWILLEY: Well, Cynthia, it’s a pleasure to meet you, first of all. [CYNTHIA LAUGHING] And I’m so honored to be on the show. And you can call me Nicky.

GRABER: Great.

TWILLEY: I am, of course, the co-host of Gastropod. You might’ve heard of it. It’s, it’s pretty awesome.

GRABER: I’ve heard a little about it, yeah.

TWILLEY: And so have you dear listeners, because you’re in fact listening to Gastropod, the podcast that looks at food through the lens of science and history, and I am indeed Nicola Twilley.

GRABER: And I’m Cynthia Graber, and here it is at long last, the episode we’ve been waiting for!

TWILLEY: Drumroll please.

GRABER: Nicky’s refrigeration book!

TWILLEY: Or as it is known online and in the bookstores, Frostbite: How Refrigeration Changed Our Food, Our Planet and Ourselves. It’s coming out on June 25 and you can and should pre-order it now. Not that I’m biased. But we’ve got a bunch of extremely delightful limited edition Frostbite fridge poetry magnets to give away to lucky listeners who email us with proof of purchase at [email protected].

GRABER: So this episode of Gastropod obviously isn’t about everything in the book, that would be impossible, but I picked some of my favorite stories, and I got to turn the tables and interview Nicky about them.

TWILLEY: That Cynthia, she grilled me. Now I need a nice cold beer. But first, the scoop on Frostbite.

GRABER: Gastropod is part of the Vox Media Podcast Network in partnership with Eater.

[MUSIC]

GRABER: Well, so, let’s dive in. I have a lot of questions, and obviously we cannot cover everything in the book. It is totally fascinating and everybody should go buy it. But one thing is, it’s hard to imagine—refrigerators are such a part of our everyday lives, but there was life before refrigeration. So how recent an innovation is this in our lives?

TWILLEY: Yeah, I mean, even though I have spent the past decade researching this book, this is always still surprising to me. Because, I feel as though, a refrigerator feels like, how could you live without one? And yet, most people did until a hundred years ago. Most people still do on a planetary scale. Most Americans still did, until a hundred years ago. So yeah, it’s just a weird thing, refrigeration is really pretty new. It was commercialized in the late 1800s. It was domesticated in the 1920s. We haven’t even known how to create cold at will, for more than 150 years.

GRABER: But people must have realized a long time ago, you know, back in evolutionary history, that cold was somehow preserving. So when, how far back did people realize that cold could help make food last longer?

TWILLEY: This is probably one of those things that humans noticed, I mean, as early as humans started noticing things. So, probably for millennia, definitely there are, archaeologists who believe that in Neolithic times, humans were using, like, the natural cold of caves to store food. Or you know, ice in sort of pits in the ground to store mammoth meat and things like that. The first written evidence goes back nearly 4,000 years to the Middle East. What is now Syria. On the banks of the Euphrates, there were ice houses, apparently. We don’t know what they were using that ice for, at all. There’s just a written reference to the fact they were there. They were heavily guarded. And they were so in demand that the ice would run out within three days of being brought down from the mountains. That’s—that’s all we know.

GRABER: The Middle East wasn’t alone in having these ice houses, China had them thousands of years ago, too. But it took until the 15 and 1600s before they became widespread in Europe. What, what changed?

TWILLEY: Well, so this was a breakthrough. At the time, like the 1600s, the late 1500s in Italy, it’s the Renaissance. So people are discovering all sorts of things. And one guy in particular, Gian Battista Della Porta, he’s sort of this polymath. And he figured out how to make ice cream, basically. He was the first that we know of, to notice that if you add salt to ice, it lowers the freezing temperature, and that allows you to freeze water, it allows you to turn like a custard into an ice cream. It allows you to turn wine into a slushie, delightfully. And this was news you could use in 1600s Italy. So all of a sudden, the elite, they have a new use for this ice.

GRABER: You know, one of the things I love is what you said about ice slushies. It’s not like they were putting their chicken breasts in there. They were actually like, using the ice for frosés.

TWILLEY: Oh, it was totally frivolous and hedonistic, the use of ice. No one was using ice for practical reasons. It was entirely for the enjoyment of something cold on a hot day. And why not? I mean, a [LAUGH] a wine slushie is one of humanity’s greatest inventions.

GRABER: Totally delicious. To stay with ice, there’s a really fun story about a, a guy on a quest who lived in my region of the world, in New England. So let’s talk about Frederick Tudor and his role in the development of refrigeration.

TWILLEY: Yeah, I love this story because also, for a brief moment, New England was like the Saudi Arabia of the world where, because it had so much water and so much cold, it was like this—this vast resource, like Saudi oil.

GRABER: I love that our, like, our weather, which is the thing that we New Englanders can’t stop talking about and how cold it gets like that was the selling point.

TWILLEY: Exactly. You had this brief window where it was like, this is, this is the key to wealth for New England. That, sadly, is past. Now you just get to shovel out your cars.

GRABER: Sorry to hear it. But let’s get back. So how about Frederick Tudor? What did he do with our cold?

TWILLEY: He was a wealthy son of a Boston family. They had a summer estate with an ice house on it. So he was familiar with, you know, harvesting ice and storing it to use to chill your drinks and wine and custards in the summer.

GRABER: So far, okay, he’s a random wealthy New Englander who had a country estate that had a lake, and when it froze over they sawed up ice and stored it in blocks, you actually visited people doing that today. But what made him so unusual?

TWILLEY: He’s [LAUGH] he’s sort of a weird kind of combination of delusional and genius. He dropped out of school at 13. He couldn’t be bothered anymore. And he just spent the rest of his life coming up with get-rich-quick schemes. But what happened to him is he took his brother, who was an invalid, to Havana for some, you know, restorative sunshine. And he was like, wow, it’s really hot here. I mean, he came from New England.

GRABER: Shocking. [LAUGH] Oh my gosh, it’s hot in the Caribbean.

TWILLEY: Yes. It was more shocking then, than now possibly. So, so he was like, gosh, it’s so hot. Imagine how much they’d enjoy one of those, you know, wine slushies we can make back in Boston? I bet if I could sell them ice, I’d make a fortune. And so he goes home and then starts writing letters to investors saying, you know, soon I will, you know, have made so much money I don’t even know what to do with it.

GRABER: And investors thought he was out of his mind. What does he have to do to get this project off the ground?

TWILLEY: Well, he squeezes some money out of his brother-in-law, always handy to have some in the family. And he harvests some ice, and then it turned out that he hadn’t thought it through. He hadn’t thought through the fact that, for example, none of the Boston ship owners would carry his ice because they were like, dude, it’s going to melt.

GRABER: Seriously.

TWILLEY: And then it will flood our ship. And that’s a bad thing. He hadn’t thought about the fact that at the time of year that it’s cold enough to harvest ice, Boston’s Harbor would likely be frozen over and so no ships would be able to leave. He hasn’t thought through the fact that in Cuba, it’s going to melt. And also the Cubans, can you believe it, are just like, what is this? What am I supposed to do with it?

GRABER: This is probably my favorite part of the story with all of the things that he’s doing wrong is that he gets there and they’re all like, why are you bringing me ice? [LAUGHS]

TWILLEY: Yeah. They’re like, I don’t know what the point of this is. I have nowhere to put it. It’s just going to melt. Why would I buy a lump of frozen water that is going to melt on my way home?

GRABER: So what finally made this a success? Because it was a success. It was not a get-rich-quick scheme, but he did eventually get rich. What worked?

TWILLEY: Yeah, it was get rich slow. I mean, there was a decade where he was arrested three times for debt. He was jailed twice. And, in his diary entries, he just has the word anxiety printed in block caps repeatedly.

GRABER: [LAUGHING] That sounds kind of familiar.

TWILLEY: I was going to say, so relatable. And he writes himself these little pep talk notes too, where he’s like, don’t worry, you’re still young. Give it another go and then you can just get out of it and live a regular life. It’s not over yet, you know.

GRABER: I love all the little attempts at like, boosting himself up. But it does seem like it worked out, right? He did eventually succeed, so how did he turn it around?

TWILLEY: Well, he hired a really smart guy, Nathaniel Wyeth, who figured out how to store ice so that hardly any of it melted. Frederick Tudor himself then worked on like, how do you sell this? So he came up with a subscription model where he delivered the ice. He came up with his own design of a like, ice cooled water jug that he would give away for free. He came up with these, what he called little ice boxes that were basically early refrigerators cooled by ice. So he figured out all that stuff. And then, the part I love the most is no one could figure out how to tax him because [LAUGHS] they were like, well, it’s not mining. And even though it’s called ice harvesting, it’s not really farming. So we don’t know how to tax him. So it’s tax free. So, so that helped too.

GRABER: That must’ve been a bit of a benefit for him. But what was this, ice that he was shipping from New England lakes, where did it go and what was it used for?

TWILLEY: The ice could be taken all around the world. It was, there was a thriving trade in taking ice to Calcutta, in India. So it was being shipped everywhere. And at scale. The American ice trade at its peak was 8 million tons of ice harvested a year. But I mean, given the population of the country at the time, that’s a lot.

GRABER: And what were people doing with it?

TWILLEY: Well, so at first, as before, people used it to cool drinks. It really kind of democratized this elite luxury. So for the first time, regular people could enjoy ice cream. But then it was so abundant that people did start to use it to cool food. Fishermen started to use it to cool their catch, farmers would use it to keep their butter cold on the way to market, even people who were shipping meat started to use natural ice. And actually, the biggest users were primarily brewers.

GRABER: Smart. Nice to, have a way to keep your beer cold.

TWILLEY: Yeah, I love, I love this aspect of refrigeration’s history because, you know, one of the arguments is the reason we first started to farm is because we wanted to make beer. Well, definitely the reason we got into large-scale cold is because we wanted to make lager beer specifically. So in the 1850s, a lot of Germans, there was a huge wave of German immigration to the US. Germans love lager. Unfortunately, in a lot of the US for at least six months of the year, it’s often too hot for lager yeast to brew. And so brewers were the largest consumers of natural ice in the whole of the U.S.

GRABER: I love that. So one thing that’s really interesting is that, somebody had figured out, even before Tudor was around, that there was a way to make things cold without ice. But until Tudor showed that there was a demand for it, nobody was interested in that. So when did somebody figure out that you could actually create a cold space without ice?

TWILLEY: Yeah, again, not as easy as it sounds. And a lot of people worked on it for a long time, but the first person to do it, yeah, it was sort of like a party trick. It didn’t really have a purpose. It was a Scottish doctor called William Cullen. And it was in 1755. He was a lecturer in medicine at Glasgow and Edinburgh universities. And one of his students had noticed if you put a thermometer in wine and then you took it out, the temperature would fall. We now know that’s because the alcohol is evaporating off, and evaporation kind of pulls the heat, the energy away from the bulb of the thermometer. So that’s why you’re getting a cooling effect. But people didn’t know at the time. In fact, side note, most people don’t know how cold is made today, including me until I actually built a refrigerator for this book. So anyway, William Cullen’s intrigued. He does some experiments. He sets up this system where he has a glass of water in a vacuum and a very fast evaporating liquid in another glass inside this vacuum chamber. And that’s how he freezes the water. And he did it, and he was like, bingo, wrote it up in a paper that I think no one read. And was like, this seems like a very curious thing. Probably someone should look into it. And that was that, because no one knew what to do with that. Until Frederick Tudor showed that if you could, you know, produce cold as it were at scale, then you could have all of these new industries and all of these new—like a beer supply chain, a food supply chain. Until Tudor showed that, at scale, cold was just like this luxury party trick thing that was like, nice and fun, but not necessary.

GRABER: So did folks then like, find his research? What happened?

TWILLEY: So just as the natural ice trade is finally taking off and Tudor is making some money, that’s when scientists, entrepreneurs really, pick up on this observation that evaporation produces cold. And start kind of tinkering with, how would you build a machine to do that. And as is always the case, I think, in science, there’s a lot of people kind of doing this at about the same time. It was an Australian journalist who, it was funny, he had started a morning newspaper in this town outside of Melbourne, Australia. Obviously, it gets really hot. And so the ink would smudge on the type in the summer. And he found that if you wiped them with ether, the evaporation again would make them cold enough to be able to print the paper. So he’s made this observation. He gets to work on the steam powered ether evaporating machine, and it takes him forever. The cave he’s developing it in blows up several times. But he eventually came up with a working refrigeration machine. So he was the first to commercialize mechanical refrigeration in 1857. He sold it to two breweries, one in London and one in Australia.

GRABER: And here we are again. [BOTH LAUGH] With the brewers.

TWILLEY: I know, cheers to that, right?

GRABER: Totally. Well, and so they must have needed, like, I imagine those early refrigerators were, like, room sized for the beer makers. Like, what were those early refrigerators like?

TWILLEY: They were gigantic, because they were steam powered. They were super dangerous, they exploded all the time—

GRABER: Great, sounds awesome.

TWILLEY: Yeah. They were uninsurable, they were one offs because they were all prototypes. And also the weird thing is that no one had made the conceptual leap, like, Oh, if we have a thing that produces cold, we could just use it to cool a space. We don’t have to use it to cool water to make ice to cool the space. So that, that conceptual leap took a little minute. Again, I have to say, it was brewers who first realized, oh wow, like we don’t have to use these machines to make ice to cool our cellars. We could just cool the cellar. And it was a brewer in Brooklyn who did it first.

GRABER: So now, in part thanks to all the beer brewers out there, we finally had mechanical refrigeration. Was everyone else as quick to put these newfangled, potentially explosive machines in their home? That’s coming up, after the break.

[BREAK]

GRABER: So in the early 1900s, a bunch of things were changing that made people more interested in the potential of refrigeration. Cities were starting to get electric grids. And so, you know, there was access to power for these refrigerators. And then also, in urban spaces, the natural harvested ice was actually kind of nasty because of pollution, so using that ice could make you sick. But mechanical refrigeration still didn’t catch on right away.

TWILLEY: Oh, for sure. People had zero trust that refrigerated food was safe to eat. And again, that is one of those things where you’re like, what? Because nowadays—like today, if you leave something out of the refrigerator, people will be like, oh, is it still good? Even after a couple of hours out of the fridge? But at that time, Americans were like, what is this weird, unnatural technology that can deliver me a chicken that was slaughtered six months ago, a year ago, and yet it looks like it was slaughtered yesterday? It hasn’t changed its physical appearance. And you have to understand that before that, if you wanted to preserve food, you did things that changed the physical appearance of that food. You had to turn your milk into cheese. You had to ferment your cabbage into, you know, kimchi or sauerkraut or something.

GRABER: Right, you had to turn your raspberries into raspberry jam. You dried food, you know, you smoked it.

TWILLEY: Exactly. And here was this new technology that actually meant that the chicken looked like it had been slaughtered yesterday. The apple looked like it had been picked yesterday. But had it? And that uncertainty, like people just didn’t know, and they had to trust that it was fresh. And they didn’t, of course.

GRABER: People weren’t totally wrong to be afraid of it, though, because nobody really knew how long to store food or at what temperature. And so in fact sometimes refrigerated food was making people sick. Scientists needed to find a way to make cold food safe. Now around that time, people were using chemical preservatives to keep food from going bad as it traveled into urban centers. We did an episode about a guy named Harvey Washington Wiley. He figured out that a lot of those preservatives were actually making us sick, and he spearheaded an actual law to make food safer for us to eat.

TWILLEY: As we say in our episode, he had campaigned for this pure food law in 1906. And then he was in charge of enforcing it. And being in charge of enforcing it meant figuring out what it—what actually was so bad about our food supply. The thing to know as well, and we said this in the episode is, at the time, more and more Americans were moving to cities, and their food was traveling longer distances, and it had to stay good over those longer distances. One thing people were using were these toxic chemicals. But the other thing people were using was this new refrigeration technology. And Harvey, he, he, he gets reports and questions from people, you know. And he realized he didn’t know how to answer them. Someone would say, well, this turkey has been in, in cold storage for 10 years. Is it safe to eat? No one knew. No one had done the science. So he decided the federal government needed to do the science.

GRABER: And he outsourced it to one of my favorite heroes in your book, Polly Pennington. Who is she? And how did she get into science?

TWILLEY: She is a rock star, really. I mean, she is, she’s like the, the mother of refrigeration in America. And she’s totally forgotten, but she was awesome. She grew up in Philly. At the age of 12, she read a chemistry textbook in a library and fell in love with chemistry. And then at the time, of course, the University of Pennsylvania wouldn’t let women enroll to study chemistry, but she persuaded them. Then when she got her degree, they actually were like, well, we don’t really give a Bachelor of Science to a woman, so you can have a Certificate of Proficiency instead.

GRABER: Oh, isn’t that so kind of them?

TWILLEY: I know. It’s nice. It’s nice. I feel like that was a big gesture. And then she was like, well, I’d like to do a PhD. And they were like, absolutely not. And she finagled her way in, into that. There was a university statute she dug up that covered exceptional cases and, and got her way in for that. And then she graduated with a PhD in chemistry, and I don’t know if you can tell where this is going, but there weren’t a ton of jobs for ladies with PhDs chemistry at the time.

GRABER: I’m shocked. Totally shocked .

TWILLEY: So she set up her own lab instead, because she was like, well, if no one will hire me, I will you know, have to run my own business. And she mostly did bacteriological samples for doctors. And she was really good at it.

GRABER: Of course she was. In your book you tell the story of how one of her early successes was cleaning up the city of Philadelphia’s milk supply. So based on that, Harvey Washington Wiley decided to hire her to kind of figure out refrigeration, but he wasn’t allowed to hire women.

TWILLEY: Yeah, it’s amazing. So again, not surprising, if you’re following the story this far, but yeah, the civil service didn’t hire women. So Harvey instead decides—he, he enters her for the civil service exam anyway, and just sort of did it without asking her permission. Just told her, I’ve entered you for the exam. She was, a little annoyed, but she decided to sit the exam anyway. He also entered her for the exam as Dr. M. E. Pennington. Everyone called her Polly, but she was, she was christened Mary. And so, but, Dr. M. E. Pennington, everyone assumed her first name was like Mark, or Michael, Matthew, I don’t know. No one knew. So she’s entered into, to take the civil service exam as Dr. M. E. Pennington. She took it, she got top marks. And before anyone could notice she was a woman, Harvey hired her and she got to work as Dr. M. E. Pennington. You know, she put on a sensible, divided skirt and set off.

GRABER: I love it. The equivalent of putting on her pantsuit, which she couldn’t do.

TWILLEY: Exactly.

GRABER: So what did she end up doing?

TWILLEY: So she basically launched something called the Food Research Laboratory, and she hired a bunch of women to staff it with her, including her sister. And they did a combination of lab-based experiments, so she would study how quickly a chicken decomposed at different temperatures, and things like that. In a lab. As well as real world sort of field research. So she traveled all around the country,with refrigerated rail cars full of chickens, just sampling three random chickens at every stop. To see what was going on, again, like in the actual food supply. And basically over the course of, I don’t know, about 20 years. She made refrigeration scientific in America. She came up with the guidelines for how you should store food, what temperature, how much cooling, for how much meat, how long you could store it. She redesigned the refrigerated rail car so it actually worked. She made refrigeration scientific.

GRABER: We’ve said that people were afraid of refrigeration and with good reason, so she did turn things around?

TWILLEY: She did. And you can see how effective she was by the fact that when she started, there were headlines around that refrigeration was going to kill people, it was so deadly. And by the time she was ready to retire in 1939, she was giving a lecture at MIT and she said to the students, things have changed so much that now, Americans don’t believe something is safe unless it’s been refrigerated. So it flipped 180 degrees over the course of her career and she was the one responsible for that.

GRABER: So eventually after all of these key developments, mechanical refrigeration spread across America. And not just in people’s homes—in the book there are stories about how some of the most important changes were in refrigerated rail cars and refrigerated shipping containers and huge refrigerated warehouses. And they helped create a world where we can have the same fruits and vegetables year round, where meat is raised on huge feedlots in one place and shipped to consumers, where a salmon that’s caught in Alaska might be deboned in China before coming back to a consumer in New York. And the book is really about the implications of this. The effects are far-reaching in many different aspects of our lives, including health, the flavor of what we eat, and the environment, and in all of these the ripple effects are huge but also complicated, it’s not a simple, “wow, that’s awesome” or “crap, what a nightmare.” You listeners will need to read the book to find out more. But I wanted to focus in on climate change. The first implication is in terms of food waste—in America, we’ve cut down on waste that used to happen in transit because of refrigerated containers and warehouses, but now people buy more food than they need, and then don’t eat it all, and throw away about a third of perishable goods, and there are major climate change implications in all that food waste. But also, there are emissions issues when it comes to the energy for refrigeration and the chemicals themselves, because those chemicals have implications in terms of climate change.

TWILLEY: Yeah, this is a sad irony where something we developed to make things cold is actually heating up our planet. But it, it also isn’t discussed a lot, because when I first started looking into this, I was like, wait, am I making a mistake? Because, everyone should be panicking about this. And they’re not, I think, largely because people think that the cold chain— you know, it’s how we feed ourselves, so it’s not optional, so I guess we just have to live with these emissions. But there are a lot of emissions, like you say. So, the energy required for cooling is currently eight percent of global electricity usage. Cold storage is the third highest industrial consumer of electricity. So it’s a lot of emissions from the power to run these, you know, refrigeration machines. And that’s not even the biggest problem, because the biggest problem is the chemicals you use in those machines, the refrigerants. And these are, majority, these days still, something called super greenhouse gases, which basically just means they’re thousands of times more warming than carbon dioxide. And, they leak out to the atmosphere. And that means that Project Drawdown, which is this project, you know, designed to look at what we can actually do, to try and contain climate change. I guess stop at this point is moot, but.

GRABER: Let’s work on containing.

TWILLEY: Exactly. They list refrigerant management as the number one solution to global warming in terms of potential impact. And they were surprised. They were a bit like me when I first started looking into this, they were like, what, really? Refrigeration’s a problem? Turns out it really is. And this is just really only the developed world with the refrigerated cold chain for its food supply.

GRABER: Well, that’s actually what I wanted to talk to you about next because, another thing I think people might not realize is not everywhere in the world has refrigerated warehouses and a cold chain the way we do. And if they build one, that has huge climate change implications. So how quickly are things changing in the developing world?

TWILLEY: Yeah, this is a, I mean this is a cool time, so to speak, if you’re into refrigeration, because refrigeration is spreading rapidly. So right now, the quote unquote “developed world” has sort of a, a largely a, a built out cold chain. It’s still expanding. The U. S. cold chain is still growing at a huge rate. But the rest of the world, and by that, I mean almost all of sub-Saharan Africa, large parts of Southeast Asia, doesn’t have a US-style cold chain, even India.

GRABER: Obviously everybody should have access to the same resources we do. We shouldn’t say we got here and now you can’t. But there’s huge climate implications. So is anybody doing research on alternatives to our current system, the refrigerants, the electricity, all of that?

TWILLEY: Right. Yeah. I mean, basically, if the rest of the world builds the same cold chain that we have here, it is a climate disaster. One climate scientist just said to me, well, listen, if everyone else builds the same cold chain that the U.S. has, there won’t be a harvest to store in that refrigerated warehouse. Because climate change will have made sure of that.

GRABER: Great.

TWILLEY: So. On that happy note, people are doing research. There are people, you know, coming up with prototypes for more energy-efficient cooling. Different methods of cooling altogether, magnetic refrigerators, acoustic refrigerators. Even Einstein came up with an alternate method of refrigerating, although actually it’s proven quite hard to make work. But, these are all pretty much prototypes. They’re in the lab. They seem promising. They’re not commercial. And the interesting thing is also—and, almost everyone said this to me. Refrigeration is like the Cinderella of engineering R&D. Less than a tenth of one percent of engineering R&D is spent on refrigeration. It is not something that the great minds are focused on. So of course progress isn’t happening very quickly.

GRABER: But there is a company doing something amazing that could help transform the cold chain without cold—that’s coming up after the break.

[BREAK]

GRABER: So you have an interesting story about something that could help make a change, and it’s a company that you and I have both been following the news about for years, so I’m a little jealous you got to visit them, it’s called Apeel.

TWILLEY: I did indeed get the chance to visit Apeel.

JAMES ROGERS: I’m James Rogers and we are at Apeel Sciences in Santa Barbara California.

TWILLEY: The interesting thing about this company is that if you think about it, all we want is for food to be preserved. We don’t actually need it to be cold. And so their whole thing is to come up with a different way to preserve fresh fruit and vegetables, keep them fresh for as long as a refrigerator would keep them fresh, but just using a totally different technique. And to come up with that, he went back to square one—what makes food go bad?

ROGERS: If you go online and do your research, immediately you learn that the leading causes of produce spoilage are water loss and oxidation. Water evaporating out of the surface of the produce, oxygen getting in.

TWILLEY: Basically once a fruit is harvested, it’s still alive, it’s still metabolizing. This is a—it’s respiring not breathing, same difference, It’s taking in gases and breathing out gases. It basically has a certain number of breaths left before it dies. And so if you can slow down how fast it’s breathing, it will last longer.

GRABER: So how does refrigeration do that?

TWILLEY: Everything happens more slowly in the cold. The fruit just breathes and metabolizes more slowly, so it also dies more slowly. But James was a PhD student, his field was creating nanoscale coatings. And that gave him the idea that you could design a coating to go around a fruit or vegetable that would kind of do the same thing as refrigeration—a coating that would slow down its breathing and water loss.

ROGERS: Every single living system needs to insulate itself from atmospheric conditions. And so, this idea of creating a barrier around something is not at all novel. In fact, you know the original lipid vesicles that developed were the cradles in which life was actually able to first develop on this planet. So it’s almost like a prerequisite for life that you were able to insulate and create these kind of more favorable little conditions in a particular system.

GRABER: That sounds like a great idea in theory, but evolution had a long time to work out those barriers, so what did James and his team have to do?

TWILLEY: It’s all about relaxation. And you can see if you, wire up these fruit, you can see it having a panic attack when it’s taken off the plant. It’s bananas. It starts breathing really heavily. And when it’s breathing really heavily, it’s not just aging, it’s consuming its internal resources. So all of those, you know, vitamins and phytonutrients that we want to eat, it’s burning them up in this sort of, panicked attempt to stay alive. Because it’s like, ah, I’ve been cut off from the parent plant. So, figure out exact conditions that would sedate this panicky fruit and cause it to make as slowly as possible. And that comes down to getting exactly the right blend of oxygen carbon dioxide water and vapor.

GRABER: Okay so now he knows the right conditions for a super relaxed piece of fruit—how does he build the barrier to create that kind of crop anesthesia?

TWILLEY: Well, so that’s where his thin layer expertise came in because he knows how to design a barrier that will deliver exactly the right amount of oxygen and carbon dioxide. So what he has to do is figure out what to make this barrier from, and he wanted to make it only from molecules that you find in food. Because, that way its FDA approved already, its perfectly safe, we know its edible and not going to cause any harm to anybody. And so at the Apeel labs they have this entire search process for finding useful molecules in food. And what they do is they tap into food waste. So they look at the leftover stuff from pressing grapes, or olives. Or they’ll go to a guacamole factory and take the pits and the skins. When I was there they were analyzing a bunch of tomato skins from a canned tomato factory to see if there was anything useful in there.

ROGERS: And basically what that comes down to doing in a very crude analogy is we basically pressure cook the hell out of this material. Because inside of here there are millions of different kinds of molecules and some of those are really useful for our formulations and some of them are not at all useful for our formulation. So our job is first, to get access to the molecular building blocks, and then we think about how we construct our formulations.

GRABER: So he breaks down the tomato skins, he isolates and analyzes molecules to find the ones that are useful, he can create these super thin films made of a variety of them, he kind of comes up with what he thinks will be just the right recipe. And then he has to figure out if it works.

ROGERS: So what we’ll do is we’ll take an untreated piece of produce, we’ll measure the characteristics of that produce without our treatment. We’ll treat it, and then we’ll measure the characteristics of that produce now with the treatment applied.

TWILLEY: Basically, he takes a perfect avocado, freshly picked, he gives it a thorough check up and measures all its vitals—how much vitamin E it has, how much of different fatty acids, how much of all the different flavor chemicals that make it taste like an avocado. And then he sprays his coating on, leaves it for a while, and measures the avocado again to see how much of the good stuff is left.

GRABER: But isn’t each type of produce different? Like a strawberry would be different from an avocado would be different from a pepper. What did they, what did they do to figure that all out?

TWILLEY: Yeah, not even. I mean, a different variety of avocado would be different from a different variety of avocado. Everything has its own perfect little microclimate. So, when you visit Apeel, it’s just this enormous playground of instrumentation. They dunk avocados in these little water baths and sort of create this vacuum around them to, to sample the atmosphere. They have multiple testing labs where they’ll spray slightly different versions of the formulation that will dry at slightly different rates, to see which does better. And then they test each one to see, okay, which has higher levels of vitamin C still, which has, you know, higher levels of this chemical that was high when it was still on the plant. So it has been a lot of trial and error and testing to arrive at different formulations for different fruits and vegetables, that preserve them in as close to the state that they were on the plant as possible.

GRABER: So how well does it work?

TWILLEY: I saw the magic in action.

ROGERS: These are untreated lemons. So this is eight weeks old. And these are the same age. So these are treated and these are untreated.

TWILLEY: That’s nuts. I mean look at them.

ROGERS: Peppers, the same thing. So untreated, and these are treated and they’re both the same age. You should feel it actually, I mean, they’re solid.

TWILLEY: Wow. And does it still smell like a lemon?

ROGERS: Oh yeah.

TWILLEY: Let me just repeat that—bell peppers for eight weeks at room temperature!

GRABER: And we know what happens to that usually.

TWILLEY: You don’t even need to know. They have bell peppers that are coated sitting next to bell peppers that are uncoated for eight weeks at room temperature, and the uncoated ones have basically dissolved. I mean, they’re moldy, they’re shriveled, they’re tiny and slimy, and they—I mean, you would not eat them. The other ones, yeah, they’re past their prime, but you would totally put them in a stir fry. You might not put them in your crudité board, but you would cook with them.

GRABER: And so, does the coating taste like anything?

TWILLEY: I did ask, you’ll be proud of me, Cynthia. I was like, can I lick this?

[BOTH LAUGH]

GRABER: Of course.

TWILLEY: Like the good investigative journalist I am. And they were like, yeah, yeah—

ROGERS: Yeah, that’s the whole key. What we do is we treat the produce with such a small amount of material, that the result is you can’t see it, you can’t taste it, you can’t feel it.

TWILLEY: So if I licked that right now I would not taste anything.

ROGERS: Go for it.

TWILLEY: So I did. I picked up an Apeel coated lime, and I licked it, and it tasted like a lime. Like I said, it’s a nanoscale coating, it’s totally imperceptible.

GRABER: So is Apeel, are these Apeel coated fruits and vegetables already on the market?

TWILLEY: They are. You can currently buy Apeel coated cucumbers, which is great because cucumbers in supermarkets go bad so quickly. Apeel coated lemons, Apeel coated avocados. They have a few different formulations they’re working through. You might think, oh, they have the spray, they could do it. No, they have to develop a new formulation for each thing, but they also have to develop a new kind of application system. So whatever they do has to fit in a cucumber packing warehouse. So they’re designing sort of an end to end solution. They’re working with the growers and the packing house, and then all the way along the food chain and the supermarket to figure out how to make this work. So they’re going one fruit or vegetable at a time.

GRABER: This sounds amazing, and it’s easy to see how this could reduce food waste, obviously. And if it’s used to keep products out of the cold chain altogether, it could also save a lot of electricity and reduce emissions, which is great. So is this kind of their target goal?

TWILLEY: Yes, but it’s just one of their target goals! They also want to get produce to supermarket shelves with more of the things that make it tasty and good for us still in it. Refrigeration is just a one size fits all solution, it’s typically not optimized for each different species at the grocery store, so it’s possible that actually Apeel can work better to slow down how fast fruit is breathing and keep it in better shape. James has even more ideas for what Apeel might be able to do.

ROGERS: The thing that actually makes me personally most excited about what we’re doing is being able to bring in greater biodiversity of produce to retail shelves. Because the number one characteristic that people breed for today is transportability. If it’s not transportable, it’s not economically viable. And so the likelihood of doing a breeding experiment and getting something that’s transportable and has great flavor and looks great is really really low. And so if we can come in with our technology and release or reduce the perishability constraint and solve the transportability problem we can allow people to select for traits which are, you know, nutritional, or flavor, you know. Or grow better in local growing environments

TWILLEY: This is exciting because there’s a lot of amazingly delicious and sustainable and nutritious fruit and vegetables out there that you can’t get in the supermarket because they can’t be shipped and stored under refrigeration. Apeel could get around that problem.

GRABER: Maybe this is what will finally get pawpaws on to our grocery store shelves! But Nicky, as we were talking about, a lot of the world is starting to create a cold chain, and that’s important for them but also could have dramatic climate change implications. Maybe Apeel could help them get some of the benefits of refrigeration without refrigeration.

ROGERS: That’s right. The same way that, you know Africa never had landline telephones, and they went straight to cell phones, we believe that by implementing this technology correctly we could help sub-Saharan Africa in particular leapfrog the development of a cold chain. And you know, use that to develop a completely different food supply chain which could help lift billions of people out of poverty.

TWILLEY: Thinking about the implications of this is kind of amazing. So for example, in countries that don’t have a cold chain already, well now those farmers don’t have to build one. That’s exciting because it’s really expensive to build a cold chain. This is less expensive, or at least it has the potential to be. I mean, when you’re prototyping it, it’s very expensive. But as a commercial technology, it’s made from waste food. You buy the powder and spray it on. As opposed to the enormous cost of running a refrigerated warehouse. When I visited Rwanda, no one, even places that had a refrigerated warehouse, they wouldn’t run it. Because it was too expensive. And the other thing is, it’s too expensive for an individual smallholder in Rwanda to have their own refrigerated warehouse. They have to scale up. You just can’t make the economics work at small scale. But you could maybe make the economics of Apeel work at small scale. And maybe that means that some African farmers can stay on the land, and we can have a different farming system. Here in the West, you know, farms are massive and very few people farm. Well, maybe that could be a different model elsewhere, you know.

GRABER: I have to say, I am very excited to watch and see how things go with Apeel and I wish them a lot of success. But now for the big picture, so Nicky, you have now spent a decade of your life off and on obsessed with refrigeration.

TWILLEY: Don’t remind me. [BOTH LAUGH]

GRABER: Do you, if you had to give a big takeaway, if you had to give one, I know obviously the topic is really interesting, but kind of what’s your big takeaway and like, why should people care about it?

TWILLEY: Well, I think the big takeaway is: cold revolutionized our food chain really recently in a lot of different ways. And I take away from that the fact that we can revolutionize our food chain pretty quickly. And that’s something we clearly need to do. But also, I think people should care about it now, because we implemented this in a very… sort of commercial way. I mean, people just figured out how to make it work. The government stepped in and figured out how to make it safe. But no one said, well, is this giving us the food system we want? Is this making our food system resilient? Is this making our food system equitable? Is this making our food tasty, healthy? You know, what is this doing to labor? What is this doing to the environment? And it turns out to have negative effects in all of those areas. And, if we never look at those and are instead just like, Oh, we have to refrigerate because that’s our food system. Otherwise food can’t reach us. I mean, why, why would we let it go unexamined? We could design a different food supply chain. So, my feeling is the moment to, to look at this is now, partly for ourselves, definitely because the rest of the world is building a cold chain, certainly because of the climate change impact and the fact that we have to reduce those emissions. But also just because, it could be different. And that’s why I love the story of Apeel. There’s nothing there that says refrigeration is the only and best way to preserve food.

GRABER: Thank you so much for joining me today on this episode of Gastropod.

TWILLEY: Like I had a choice.

GRABER: Nicola Twilley is co-host of Gastropod and the author of the new book Frostbite. [LAUGHING] I don’t know the entire subtitle.

TWILLEY: How refrigeration changed our food, our planet, and ourselves.

[MUSIC]

TWILLEY: We just talked about my book for a whole episode and we barely touched the tip of the iceberg! Pun intended. There’s so many more weird stories and fascinating history and science in there and if you’d like to buy it, I will be eternally grateful. Plus if you do, and you want to send in proof of purchase to [email protected], you might win the world’s cutest fridge magnet! Make sure to come see me on book tour too—all the dates and details are on gastropod.com.

GRABER: We also have links to how to buy the book on our website gastropod.com, and thanks as always to our fantastic producer Claudia Geib.

TWILLEY: Thank you Cynthia for having me on the show, and thank you also to the team at Apeel—I loved my visit there.

GRABER: We’ll be back in a couple of weeks with a brand new episode. ‘Til then!