Science Friday - The Science And History Of Refrigeration

Episode Date: August 1, 2024

You know that disappointing feeling when you’re ready to make a delicious meal, but you crack open the refrigerator only to find mushy tomatoes, dried-out bread, or oozing strawberries?Refrigeration fundamentally changes the chemistry of our food, but at this point, most of the United States’ food system relies on the use of refrigerators. Almost three-quarters of the food on an average American’s plate has been refrigerated during production, shipping, and storage. So how did we end up relying so heavily on the fridge? And on a warming planet, can refrigeration keep its cool?A new book called Frostbite: How Refrigeration Changed Our Food, Our Planet, and Ourselves challenges the definition of “freshness” and our relationship with the fridge. SciFri’s John Dankosky talks with author Nicola Twilley, co-host of the podcast “Gastropod.”Read an excerpt from Frostbite: How Refrigeration Changed Our Food, Our Planet.Transcript for this segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

The invention of refrigeration transformed how we eat, what we eat, and when we eat it, sometimes in mind-boggling ways. You know, you hear about Silicon Valley guys doing all these bananas things to try and live longer, injecting themselves with the plasma of young boys, etc. This is so much weirder. It's Thursday, August 1st, but you're listening to Science Friday. I'm John Dankowski. During this scorching hot summer, I'm especially thankful for the ice cream I can pull out of the free. freezer or going into the fridge for a cold beer, all thanks to the innovations of refrigeration. It's fundamentally changed our lives for better and sometimes worse. A new book looks at how

frostbite, how refrigeration changed our food, our planet, and ourselves tracks the science and history behind refrigeration. I talked with Frostbite author Nicola Twilley, who also co-hosts the podcast, Gastropod. Nikki, welcome to Science Friday. Thank you for having me. Okay, so what is about refrigerators that made you want to write a whole book about them. Well, I mean, Americans are obsessed with refrigerators. We open them apparently on average 117 times a day, which I think has to have gone up since that study was done because it was pre-COVID. And now with all the work at home, yeah, I spent a lot of time telling people about this book

and being like, no, no, refrigeration's much cooler than you think. Butoom. But who... Exactly. So painful. It's a miracle. Any of my friends still speak to me. But really what I became obsessed with was refrigeration, not refrigerators per se,

because your refrigerator is just the tip of the iceberg. And I mean that very literally, there's an entire artificial winter of refrigerated warehouses and trains and ships and trucks and juice tanks and ripening rooms. and all sorts of weird spaces that you never imagine that lie kind of behind your fridge and that get your food from the farm to the table. And that's really how the fascination started for me. People were writing about farm to table,

people were opening farm to table restaurants. This is a while back because I've been obsessed with this for a while, but people like Michael Pollan and Eric Schlosser were writing books that were like showing us the behind the scenes of our food. But they were covering the farm piece, And I was like, what about the two-piece? What about how our food gets from the farm to the table? And so I decided to go take a peek in those spaces, too.

But then when I started looking there, I found the ways that we have found to extend the life of our food are totally weird and fascinating. You know, you hear about Silicon Valley guys doing all these bananas things to try and live longer, injecting themselves with the plasma of young boys, etc. This is so much weirder. Well, you actually, you tell some of these stories about the weird things that we do. So let's take the story of the humble avocado. So I live in Connecticut in the northeast of the U.S. So it's grown in California. Explain to me what exactly happens between when it's picked and when it gets to me at my grocery store. Because there are some details in here that I just frankly can't believe. So an avocado when it's ripe, it's not a very shippable thing. We know this. It bruises very, very easily, right? And for a long time,

And that's why it was an extremely rare fruit, too. So what happened was the avocado farmers wanted to make their industry big, and they looked around and they found another squishy fruit that you can't ship when it's ripe, which is the banana, and they stole basically the banana playbook. So the deal is you harvest when the fruit is completely unripe, just green, hard, discreet. just green, hard, disgusting. And then you ship it around because it's hard and sturdy during this time. You obviously refrigerate it just to keep it fresh to slow down its respiration to stop it from getting any riper to kind of freeze it in time.

And then when it's reached, you know, the point of sale, it's a few days away from going on to the supermarket shelves. You do something called ripening. and this uses a gas called ethylene, which turns out to be the most produced organic molecule on earth, because it's the basis of all of our plastics, polyethylene. But in plants, it's a hormone. And it's just this sweet smelling gas that you blast the avocados with, and it tells them, hey, it's time to ripen. And they ripen, and from that point onwards, their shelf life is very limited,

and they have to be treated with the most tender care. But that's how they get onto your shelves. And it's a really delicate process because they get very hot as they ripen. And so you have to refrigerate them. Otherwise, they explode. And you just end up with guacamole all over the ripening room walls. Hold it. You have exploding avocados if you don't do this right?

Oh, yeah. Talk about control of nature. We are deliberately trying to sort of tell a room full of fruit like, it's time to ripen, something that would happen naturally on the vine. And when they all do it once, they generate a lot of heat. So it's a very delicate process. Okay, so there's a few different places where your book kind of broke my brain a little bit. And one of these times is when you talk about how orange juice is made. Now, if you're the sort of person that wakes up every day and drinks orange juice and loves your orange juice out of a box, you might not want to listen to this next part

as you walk me, Nikki, through the life cycle of OJ. Well, yeah, so, I mean, first of all, the carton is lying to you. It has a picture of an orange, you know, with some leaves. But listen on. It's nothing to be afraid of. The truth will set you free here. So if you have an orange tree in your yard because you live in California, Florida, or you've ever drunk fresh orange juice, you know it tastes different at different times of year.

It also has a shelf life of a baby. about 24 hours thereabouts, maybe 48. So what to do? And so the U.S. Army during the Second World War wanted to get orange juice, which is very high in vitamin C, as we know, to the soldiers as a way to make sure they had, you know, they didn't have to take supplements, they were getting everything they needed. Only problem was you couldn't can orange juice. And at the time, that was really the only way of preserving juice.

You could can tomato juice and people had that for breakfast. But canning orange juice just really the result tasted disgusting. So no one did it. So they came up, they used a method that had actually been developed at the Kodak Labs for drying photographic film. To think how this occurred to them, who knows. But to basically de-errate and de-oil the juice. So you take out everything that gives it any flavor because those are the volatile pieces. Those are the parts that will go bad over times.

You take them out, you concentrate it down, you're left with orange-colored sugar water, and guess what? It lasts forever. They have these tanks where it's just like these giant ice cream paddles going around, two-story high tanks, full of this kind of viscous brown sludge, just being stirred, and you can keep that for two years. The problem, of course, is that it doesn't taste of anything, right? If you add water back to that, it will be an orange-sugary,

drink, but it won't taste of orange. But the genius is that the companies who figured this out, primarily Minutemade at first, they saw what was a problem was actually an opportunity. Because you've taken out all the flavors by de-erating and de-oiling it, you have to add them back in. But guess what? You can add them in at exactly the same ratio every time. And once you have something that tastes the same all year round, you have a brand and you have something that people can prefer, say, to other orange juices, the same way you might prefer Pepsi to Coke. And so it really takes off. An orange juice consumption, after this method comes in, orange juice consumption quadruples in a decade. It goes from nothing to being something that everyone has for breakfast. Okay, so there's a lot to unpack there. But I'd like

to turn back to produce. By the time that most of it has been done, delivered to us, it's pretty fundamentally different than when it was picked. Like, I don't know, my tomatoes are mushy, the strawberries are oozing sometime. How does refrigeration change the chemistry of these fruits and vegetables? Yeah, it's a funny thing. It's done this in a couple of different ways. But the tomato is a classic example on a couple levels, because for one, if you put it in your home refrigerator for three or four days, that's long enough. That exposure, of the cold is long enough to switch off the DNA that is the machinery for creating flavor. The other thing is, okay, remember the problem of squishiness, tomato is also very squishy when it's

ripe. There's no way you're going to be shipping that around the country. The losses are going to be horrendous. You'll end up with sauce. So what they do is they have to harvest it when it is green and hard and unripe. And again, you gas at using this plant hormone when you're at the destination. and it ripens, sure, but it never ripens the same way off the vine as it does on. And the third piece is, well, because we wanted a tomato that we could ship around and, you know, basically practically play ping pong with, we bred for a tomato that we could do that. We bred for the sturdiest tomato possible.

Guess what we didn't breed for? Flavor and nutrition. You can actually survey heirloom tomatoes and see which genes are missing from the commercial variety that we just bred out because they weren't useful in delivering the tomato of commerce. There's actually a lot of fascinating chemistry and even engineering in things as simple as those salad bags that we get are pre-washed greens. And maybe you can talk about how those bags are designed to keep these delicate greens fresh while they're in the refrigerator. Yeah, I mean, I have to confess before I wrote this book, I just thought a salad bag was a plastic bag, like nothing special there. actually it turns out it's a high-tech respiratory apparatus.

It is specifically creating the perfect atmosphere inside the bag to slow down how fast those leaves are breathing. So the trick with produce is once you harvest it, it's still breathing. They call it respiration technically, I think not to freak us out, but really it's breathing. And like us, it has a certain number of breaths it can take before it will die. And so the whole trick of everything we do to our produce is to make it breathe more slowly. Refrigeration slows down how fast produce breathes. So does it lowering the oxygen levels and tweaking the atmosphere very precisely.

And so what those salad bags do is they are multiple layers of differentially permeable membrane, which just basically means they have different kind of microscopic holes in them. that are tuned to let different amounts of the various atmospheric gases and water in and out of the bag, matched precisely to the leaves in the bag and how fast they're breathing and what they need. And that leaf mix, too, you think, oh, they put in the baby spinach and the arugula and the endive and the radicchio, because they taste good together. No, no, no. They're balancing each other out. So baby spinach breathes really fast. It's so young. You know, we harvest it when there are only five true leaves on the plant. And it's just like, you know, Radicchio is breathing much more slowly, much more chill. So you balance that out. You basically kind of put the blend together in the right ratio to get an even kind of breathing rate. And then you design the bag to match that. And then someone like you or me buys that bag, come.

home, realize it doesn't fit in our crisper drawer, and opens it and ruins everything. Okay, so, of course, as the planet gets, we're working harder to stay cool, and that goes for our food, too. How does refrigeration play into a warming world? Yeah, it's, this is the, this is the scary part, because of course, as the planet warms, we need to work harder to keep things cooler. And as, you know, much of the rest of the world develops and builds the same kind of food system that we have here in the U.S. You know, China's basically built that now is still expanding. Sub-Saharan Africa is just embarking on building this, but it takes an enormous amount of power.

So currently about 2% of global electricity usage is for cooling food, that will increase at least fivefold as the rest of the world comes online and more as temperatures rise. plus the chemicals we use to refrigerate food are actually global warming super greenhouse gases. So they're much more polluting than, say, carbon dioxide, many thousands of times more as they leak into the atmosphere. And so the combination is actually a disaster. And the irony is that, you know, as our natural ice caps, our natural cryosphere melts, the Arctic disappears, the Antarctic disappears. we're building this artificial winter, this artificial cryosphere that's expanding rapidly. I mean, it increased by 20 percent between 2018 and 2020 alone.

So as that expands, the natural one shrinks and the two are connected. Has all of this changed the way that you think about the food that you eat? I mean, I definitely never opened the salad bag just to squeeze it into my crisper drawer anymore. And yes, absolutely. having seen kind of people who specialize in this kind of shudder and horror at the idea of putting a peach in the refrigerator, I never do that anymore either because, I mean, I, I, the words, the stone fruit killing zone just kind of echo in my head. So definitely I have a sense, much more so, I think, that the refrigerator is just one solution for keeping food fresh,

and that also things don't get fresher in there. It's not, a bank fault where you put something in and it stays exactly the same and you could take it out a week later. If you put that bag of spinach in there and you eat it a week later and it hasn't gone bad, you might be patting yourself on the back, but it's going to have half the nutrients it did when you first put it in. To me, it's just one of the ways that we preserve food. It's not the only way. It's not the best way. And it's definitely not necessarily the most sustainable way. And at the end of the book I spent some time looking at, you know, people working on other ways to keep food fresh, because that's the thing to remember. For beer, we want it cold. For everything else,

we want it fresh. And there's a lot of ways to do that. It doesn't have to mean cold. I guess the last thing to ask you about, and you touched on this earlier when we were talking about taking that tomato and putting in the refrigerator, I'm wondering if the food that we have today is just substantially different because of refrigeration than the food our grandparents had. Oh, absolutely. And you can even see people foretelling that this will be the case. In 1911, there was a cold storage banquet held in Chicago

to introduce people to this wild new food preservation technology that they were actually very suspicious of. And one of the editorials that came out around this kind of promotional meal to convince people that refrigerated food was safe and wouldn't kill them, said, listen, it may not kill you. But it doesn't taste the same, and the only silver lining is that soon the generation that knows what fresh food tastes like will be dead, and the generations that follow will think that refrigerated food is fresh.

That's, you know, we just won't know what we're missing. And when I read that, I got chills down my spine, because we are that generation. and we have forgotten what food tasted like before it met the cold chain. And, you know, I think we've lost out as a result. I should say, we have gained in other respects. You know, most of those people would never have tasted a banana, you know, or a ripe avocado. And again, so there's flavors that it's brought to our table, but there's flavors that's taken away. Nikki, thanks for this interesting historical look at refrigeration.

I really appreciate it. Thank you. This was fun. Nicola Twilly is the author of Frostbite and co-host of Gastropod. To read an excerpt from Frostbite, you can head to ScienceFrily.com slash Frostbite. That wraps up this week's show. Lots of folks helped to make it happen, including Rasha E.D. D. Petersburg. Sandy Roberts.

Shoshana Bugsbaum. Coming up on tomorrow's episode, we'll round up this week's science news. I hope you can join us. I'm John Dankoski.