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Planet Money

How refrigeration took over the world

with Nicola Twilley

Published September 26, 2025
View Show Notes

About This Episode

The episode explores how refrigeration and the modern cold chain emerged, from Gustavus Swift's centralized meatpacking and refrigerated railcars to the scientific work of chemist M.E. "Polly" Pennington, who standardized safe temperatures and built public trust in chilled foods. Hosts and guest Nicola Twilley trace how continuous refrigeration reshaped agriculture, consumer expectations of freshness, women's household labor, and even geopolitical events like war logistics and Irish independence. They also examine the downsides of a cold-dependent food system, including diminished flavor, shifted food waste, and significant climate-warming emissions, along with potential efficiency improvements.

Topics Covered

Refrigeration Cold chain logistics Food systems Food history Industrial history Global food trade Climate change Gender norms Sustainability War and empire

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Quick Takeaways

  • Modern refrigerated warehouses keep produce in a kind of suspended animation by carefully controlling temperature to slow its respiration and extend its shelf life.
  • Meatpacking pioneer Gustavus Swift centralized slaughter in Chicago and developed effective refrigerated railcars and chilled plants, dramatically cutting meat prices and enabling full use of animal byproducts.
  • The cold chain links farms to home refrigerators through a continuous series of cold spaces, allowing long-distance trade in perishable foods and concentrating production in the regions with the best climate and soil rather than those nearest to cities.
  • Chemist M.E. "Polly" Pennington systematically determined safe storage and transport temperatures for foods and helped overturn public suspicion of refrigerated products, leading to modern grading and safety standards.
  • Refrigeration transformed daily life and society by reducing women's time spent on food preservation and shopping, supporting women's entry into the workforce, and influencing events from World War II medical logistics to the political economy of Central America and Ireland.
  • Refrigeration has trade-offs: it often reduces the flavor and perceived freshness of food, shifts a large share of food waste to the consumer end, and accounts for around 2% of global greenhouse gas emissions.
  • Small technical choices, like setting freezers at minus 18 versus minus 15 degrees Celsius, can have outsized climate impacts, with a modest temperature increase potentially equating to millions of cars' worth of emissions avoided.

Podcast Notes

Refrigerated warehouse tour and living produce

Host visits a large refrigerated warehouse

The host describes donning a hairnet and beard net and entering a shipping dock that smells of produce, with pallets and racking everywhere[0:38]
The warehouse is framed as a low-key wonder of the modern world capable of feeding an entire city[0:46]

Introduction of guide Nicola Twilley

Nicola Twilley is introduced as a food journalist, host of the Gastropod podcast, and author of a book on refrigeration called Frostbite[1:02]
Nikki has spent the last decade visiting refrigerated warehouses and even working in some of them, becoming obsessed with this world[1:13]

Scale and operations of the warehouse

The warehouse is described as the size of two football fields, with moving equipment that the host must avoid being run over by[1:23]
Fruits and vegetables arrive from all over the world and are distributed to supermarkets and restaurants across Southern California and beyond[1:33]

Concept of produce in suspended animation

Nikki explains that harvested fruits and vegetables are not exactly dead; they are still breathing and in a kind of suspended animation[1:49]
• She compares produce to humans, saying both are alive, breathing, and have a limited number of breaths before they die
The main trick with produce is to make it breathe more slowly, which refrigeration accomplishes[2:18]

Specialized microclimates for different crops

The warehouse contains storage rooms with specific microclimates tailored to be the perfect temporary home for particular fruits and vegetables like bell peppers and jackfruit[1:39]
Nikki leads the host through vinyl strip doors into a room designed for eggplants and tomatoes and asks if he feels the temperature change[2:31]
The tomato room is noticeably warmer than the previous area and is kept at about 45 degrees Fahrenheit[2:45]

Tomatoes' sensitivity to cold

Nikki insists on pronouncing tomatoes the British way and jokes that listeners should deal with it or try it themselves[3:02]
She explains that tomatoes are extremely sensitive and if stored too cold for too long they lose their ability to generate flavor[3:16]
• She offers practical advice: do not refrigerate your tomatoes at home
This loss of flavor from improper cold storage is given as a reason why supermarket tomatoes often taste bad[3:25]

Warehouse as cathedral of refrigeration knowledge

The host likens the warehouse to a cathedral devoted to everything humanity has learned about refrigerating food over the last 150 years[3:32]
Being there with Nikki is compared to getting a tour from the Pope of refrigeration[3:42]

Bold claims about refrigeration's far-reaching impacts

Nikki says refrigeration changed everything from the contents of the microbes in our gut to the invention of the hoodie[3:55]
She links refrigeration to Irish independence, the politics of Central America, and the very existence of the cheeseburger[4:03]
• The cheeseburger is described as not existing until refrigeration made it possible

Framing the episode on refrigeration

Episode introduction and hosts

The show is identified as Planet Money from NPR, and the hosts introduce themselves as Alexi Horowitz-Ghazi and Nick Fountain[4:17]
They announce that the entire episode will be about refrigeration, how it changed history, and how it remade time and space[4:27]
They tease that listeners will meet a chemist who traveled by train for food safety and a notorious cheapskate who brought meat to the masses[4:32]

Transition from cold warehouse to warmer space

Nikki suggests continuing the interview in a warm place and says she loves the cold but not that much, and the host agrees[4:42]

Life before widespread refrigeration and inefficiencies of meat supply

Sensory and practical reality of mid-1800s food

The hosts set the scene in the mid-1800s, describing it as a simpler but smellier time because unrefrigerated food rots quickly[6:13]
Without refrigeration, there were only about two or three days between slaughtering an animal and needing to eat the meat before it spoiled[6:24]

Economic and sanitary inefficiency of pre-refrigeration meat distribution

In the mid-1800s, cows were raised far from cities and then walked or transported by train into urban centers for slaughter[6:43]
Cattle lost significant weight during these long journeys, making the system wasteful[6:54]
Slaughtering animals in city centers produced horrific scenes of blood and gore near where people lived, making conditions unsanitary[7:08]

Introduction of Gustavus Swift as transformative figure

To solve the problems of cattle commutes and urban slaughter, the story introduces Gustavus Swift, described as a notorious cheapskate with a New England sense of thrift[7:12]
Swift was born in 1839; his brother Noble was a butcher, and Gustavus followed in his footsteps at age 14[7:27]

Swift's early butchering business and realization about waste

As a young butcher, Gustavus would travel from Cape Cod to buy a cow near Boston, slaughter and quarter it, and bring the meat back to the Cape to sell door-to-door[7:55]
He noticed that only about 50% of the cow was edible and the rest, such as bones, intestines, hide, hooves, and blood, was essentially trash under his model[8:06]
Swift, famous for not wanting to waste anything, knew these byproducts could be used for soap, fertilizer, and glue, but that required scale to be profitable[8:29]
• He concluded that centralizing meat production would allow collection and sale of all byproducts in sufficient volume

Centralization in Chicago and emergence of meatpacking plants

Swift moved to Chicago, then the hub for beef arriving from the Great Plains, to build large-scale operations[8:50]
He set up giant butcher shops, now known as meatpacking plants, where carcasses moved along hooks and each worker performed a specific step in slaughtering and butchering[8:53]
These operations were called disassembly lines and later inspired Henry Ford's assembly lines[9:07]
The plants were horrendous for animals and workers, and they famously inspired Upton Sinclair's novel The Jungle[9:16]
• Despite their brutality, the plants allowed full utilization of the animal, aligning with Swift's aversion to waste

Challenge of transporting meat to distant markets

Chicago itself did not have enough demand for all the processed meat, so Swift needed to ship his perishable product to East Coast cities[9:38]
Early experiments with using ice in railway cars to keep meat cold consistently failed[9:45]
• Meat touching ice suffered freezer burn and became wet
• If ice melted too quickly, excess water made meat slimy and promoted bacterial growth
• Poor air circulation caused hot and cold spots, so some meat rotted while other portions might freeze
• Train stops could cause temperature failures that ruined entire shipments
Given these problems, many concluded refrigerated rail transport for meat would not work[10:09]

Swift's iterative engineering efforts with refrigerated railcars

Swift persistently experimented by placing ice at the bottom, top, and sides of the cars in search of a workable configuration[10:39]
He tried a design with a fan attached to the railcar axle to improve air circulation, which only worked while the train was moving[10:45]
• The fan idea failed whenever the train stopped because the axle stopped turning and the fan ceased blowing
Ultimately, Swift and an engineer designed a successful refrigerated railcar that kept meat cold reliably[11:01]
• The car was well insulated, allowed ice to be added from the top en route, and used that top ice to push cold air downward automatically

Economic transformation from centralized meat processing

Swift's system worked economically because he avoided paying to ship the inedible half of the cow and also sold all the byproducts[11:25]
He was able to significantly undercut competitors' meat prices, making meat affordable for poor, previously meat-starved urban workers[11:37]

Extending refrigeration across the supply chain: birth of the cold chain

Cooling meat immediately after slaughter

Swift also innovated by cooling his packing plants so that meat was chilled almost immediately after slaughter[12:00]
This ensured beef was refrigerated continuously from the point of butchering to its arrival in distant cities[12:26]
Over time, the same approach of immediate post-harvest cooling was applied to many other foods beyond meat[12:00]

Modern grocery store abundance enabled by cold chain

Nikki points out that shoppers can buy green beans from California, strawberries from Mexico, and butter from New Zealand in an ordinary grocery store[12:19]
She asks listeners to imagine a series of refrigerated links connecting their home refrigerator all the way back to the farm where the food was produced[12:26]
For something like a green bean, the chain includes immediate precooling after harvest, cold storage, refrigerated trucking, refrigerated warehousing, refrigerated retail display, and finally the home refrigerator[12:52]

Definition of the cold chain

Nikki defines the cold chain as all the cold spaces that allow food to move from farm to point of purchase without ever leaving refrigerated conditions[13:01]

Consumer distrust and scientific standardization of refrigeration

Initial skepticism about refrigerated foods

The hosts note that for most of human history, fresh food meant something picked or slaughtered within the last few days and within roughly a dozen miles[13:35]
Refrigerated foods from far away that had been slaughtered or harvested long before challenged this understanding and seemed like a recipe for food poisoning[13:58]
At the time, refrigeration was imprecise with no standardized oversight; warehouse operators simply guessed at appropriate temperatures for different foods[14:04]
• Operators chose what seemed like good temperatures for eggs, milk, chicken, or seafood without any systematic study

Introduction of chemist M.E. "Polly" Pennington

M.E. Pennington, known as Polly, is introduced as a central figure who made Americans trust refrigeration[14:41]
She sometimes used the professional name Dr. M. Pennington so men in her era would not realize she was a woman[14:36]

Pennington's career in food safety

Pennington began working for the Philadelphia Bureau of Health, focusing on cleaning up the city's milk supply[14:50]
She later joined the federal government to determine how to safely store and transport various types of foods[14:58]

Field experiments riding the rails

Pennington traveled the country in a small train car attached to refrigerated railcars like those used by Gustavus Swift[15:06]
She sampled food such as chicken inside the cars to ensure it was being kept at the proper temperature[14:19]
The hosts repeat the phrase that she was riding the rails for food safety and mention photos of her in a sensible divided skirt reaching into ice-filled cars[15:17]
She became an icon in the food industry due to this work[15:28]

Pennington's legacy in grading and consumer protection

If you have ever checked the grade on an egg carton, the hosts say you have Polly Pennington to thank[15:45]
They credit her with helping make American chicken, shrimp, and fish safe to eat without causing illness[15:51]

Shift in American perception of refrigeration

At the beginning of her career, Americans tended to think refrigerated food was a dangerous scam[16:23]
By the end of her life, Pennington had helped Americans come to believe that food not refrigerated could not possibly be fresh, representing a complete reversal[16:23]
The hosts playfully call her a fully pasteurized grade A legend and joke about pouring out some 2% milk for her[16:38]

Refrigeration's broader ripple effects on time, space, and society

Refrigeration as a time machine and endless summer

Nikki characterizes refrigeration as a kind of time machine that can stretch the life of foods like apples for up to 10 months after picking[17:01]
The cold chain allows consumers to live in an apparent endless summer where nearly everything is always in season[17:06]

Transformation of agricultural geography

Before the cold chain, if you wanted salad greens, you bought them from whatever farmer lived near you[17:24]
Today, a large majority of lettuce eaten in the United States comes from the Salinas Valley in California and Yuma, Arizona[17:29]
• Refrigeration enables the advantages of climate and soil quality to outweigh the historical advantage of proximity to cities

Impact on women's labor and domestic life

Before home refrigerators, women spent large amounts of labor in the summer canning fruits and vegetables to last through the winter[18:13]
In cities, women typically shopped every day trying to buy fresh food for that evening's meals[18:22]
There were no leftovers as we know them today and no frozen convenience foods in the pre-refrigeration era[18:27]
As home refrigeration and frozen food expanded in the 20th century, Nikki notes that women's participation in the workforce rose in lockstep[18:32]
• The hosts also mention that divorce rates rose alongside these changes and respond with joking "no comment"

Refrigeration's role in historical events and geopolitics

Nikki cites the example of refrigerated shipment of blood for transfusions that helped American soldiers during World War II[18:53]
She notes that the ability to transport fruit from Central America changed those countries' economies[19:02]
• American corporations then did everything they could to turn some of these places into so-called banana republics
Nikki recounts an economist's provocative question about whether Ireland would have become independent without refrigeration[19:19]
• Much of the beef consumed in England was raised in Ireland, but once frozen beef could be imported from South America, the price of Irish beef fell sharply
• This price drop made life harder for Irish tenant farmers and pushed British landlords to be more willing to sell their Irish land
• These changes contributed to conditions that led to Irish independence, though even the economist does not claim refrigeration was the sole cause
The hosts treat the Irish independence hypothesis as an intriguing theory they are inclined to accept, while acknowledging its speculative nature[19:49]

Downsides and trade-offs of global refrigeration

Changes in taste and perceived aliveness of food

Nikki argues that in some ways food no longer tastes the same because of refrigeration[22:14]
People in places that have not adapted to refrigeration may taste American food and describe it as tasting dead[22:14]
She notes that cherries picked a month ago in Chile and shipped to consumers will not taste as good as fresh cherries[22:27]
• Once a cherry is picked, it begins to lose acidity and flavor, even if it remains edible with refrigeration
Overall, refrigeration has given us more food and lower prices but often at the cost of some deliciousness[23:26]

Food waste shifting along the supply chain

Before refrigeration, between 30% and 40% of food spoiled before it even reached the market and had to be thrown away[23:01]
Refrigeration dramatically reduced this pre-market waste, but overall waste has not disappeared; it has shifted closer to the consumer[23:12]
On the consumer end, including household purchases and restaurants, food waste is now estimated to be 30% to 40% of all foods[23:12]
Because refrigeration and other factors have lowered food prices, it is easier for consumers to be careless with what they buy and store[23:16]
• One host mentions having three bags of aspirationally bought arugula in his crisper drawer, acknowledging that at least one will be thrown out
• The other host jokes that he shudders to look into his own crisper drawer

Energy use of refrigeration and climate implications

Nikki highlights the irony that as humans build more artificially cold spaces, natural cold spaces are disappearing due to climate change[23:58]
Refrigeration accounts for about 2% of global greenhouse gas emissions, a share comparable to aviation[24:01]
This percentage is expected to increase as many developing countries expand their own cold chains[24:10]

Potential efficiency improvements by adjusting freezer temperatures

Nikki mentions that some people in the industry are trying to persuade others to raise standard frozen food temperatures from minus 18 degrees Celsius to minus 15[24:40]
• Both temperatures are very cold and well below freezing, and minus 18 may be colder than necessary for safety
It has been estimated that shifting frozen food transport and storage from minus 18 to minus 15 degrees Celsius, which is still safe, could be equivalent to taking about four million cars off the road[24:40]
• The hosts emphasize how a small three-degree change in freezer setpoint could have a huge impact on emissions

Reassessment of refrigeration's significance and closing thoughts

Trade-offs and broader perspective on the cold chain

The cold chain, like other major technologies, has brought trade-offs and unintended consequences alongside its benefits[25:03]
Despite the issues with taste, waste, and climate, refrigeration has made the food system cheaper, safer, and more abundant than ever before[25:07]

Hosts' renewed appreciation for refrigeration

One host admits that before working on this story he had taken refrigeration for granted as something quietly humming in the background[25:20]
After reading Nikki's book, he now views the cold chain as a force that bends time and space and alters the economy and history[25:27]
The other host says that now every time he walks by his fridge he smiles, pats it on its stainless steel belly, and says thank you[25:42]
• He closes with the affectionate line to his refrigerator: "That'll do, fridge. That'll do."

Outro, listener engagement prompt, and credits

Call for stories about undersung economic technologies and people

The hosts ask listeners if there is an undersung technology or person who did not get their due in economic history textbooks or podcasts[26:01]
Listeners are invited to email Planet Money or contact the show on various social media platforms[26:10]

Production credits

Today's episode of Planet Money was produced by James Sneed, edited by Keith Romer, fact-checked by Sierra Juarez, and engineered by Valentina Rodriguez-Sanchez[26:20]
Alex Goldmark is listed as the executive producer, and the hosts sign off while reminding listeners to give their refrigerator a pat on its belly[26:32]

Lessons Learned

Actionable insights and wisdom you can apply to your business, career, and personal life.

1

Designing systems that capture value from byproducts and reduce waste can dramatically lower costs and open new markets, as seen in Gustavus Swift's centralized meatpacking and byproduct monetization.

Reflection Questions:

  • • Where in your work or life do you routinely discard byproducts-data, materials, or insights-that could be turned into something valuable?
  • • How could you redesign one process you own so that what is currently "waste" becomes a useful input for another activity or customer?
  • • What is one small experiment you could run this month to test whether a byproduct of your current work has commercial or practical value?
2

New technologies only achieve their full potential when paired with rigorous standards and transparent communication that build public trust, like M.E. Pennington's temperature research and grading systems did for refrigerated foods.

Reflection Questions:

  • • What tools or systems in your organization are underused because people do not fully trust or understand them?
  • • How might establishing clear, evidence-based standards and simple explanations increase adoption of a project you care about?
  • • What is one concrete step you could take this week to make an important process more transparent and trustworthy to its users?
3

Technologies that save time and stretch space-like refrigeration and the cold chain-quietly reshape labor patterns, gender roles, and even political structures, so strategic decisions should account for these second-order effects.

Reflection Questions:

  • • When you adopt a new tool or process, how often do you consider how it might change people's roles and relationships over the next five to ten years?
  • • In your current projects, who gains time or flexibility from the technology you use, and who might be taking on new, less visible burdens?
  • • What upcoming decision could you evaluate not just for its direct benefits, but for its likely ripple effects on culture, power, or incentives?
4

When resources become cheaper and more abundant, human behavior often shifts toward greater waste, so effective design must counteract our tendency to treat low-cost goods as disposable.

Reflection Questions:

  • • Which things in your life or business do you treat as easily replaceable because they are relatively cheap?
  • • How could you adjust your habits, pricing, or feedback loops so that waste becomes more visible and more costly to ignore?
  • • What is one specific item or resource you could track for a month to better understand how much of it you actually waste?
5

Small technical tweaks to system parameters-such as slightly raising standard freezer temperatures-can yield outsized environmental and economic gains, so it pays to search for low-effort, high-leverage optimizations.

Reflection Questions:

  • • Where in your operations or routines are there fixed settings or defaults that nobody has questioned in years?
  • • How might running a few low-risk experiments with these defaults uncover substantial savings in time, money, or energy?
  • • What is one "knob" you could turn-literally or figuratively-this week to test whether a small adjustment produces a disproportionate benefit?

Episode Summary - Notes by River

How refrigeration took over the world
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