Learn how cold chain technology is critical to keeping food refrigerated and safe providing consumers with food year-round while allowing growers to expand globally.
Consider the milk that you just poured over your cereal or into your coffee. The contents of that ubiquitous gallon container began with a cow, obviously to reach the door of your fridge, the milk embarked on a carefully arranged journey, during which it was consistently kept chilled and free of harmful bacteria.
That process is called the cold chain. The name refers to the interconnected network of processing plants, storage containers, and vehicles through which temperature-sensitive foods and beverages are processed, packaged, and distributed for the world’s use. Consumers may not think much about cold chain management, but dairy and meat producers—and some fruit and vegetable farmers—definitely do. It’s part science—knowing how to delay the chemical processes that cause food to degrade—and part advanced logistics, a detailed choreography that is acted out on a global stage.
Cold chain logistics are the most complex part of the world’s food web. It’s critically important, even though it’s largely invisible to most consumers. It reduces food loss due to spoilage, boosts food safety and quality, and helps balance supply and demand for certain goods. The cold chain lets developing countries export perishable products and participate in the marketplace, in some cases for the first time. It lets people in northern climates eat exotic tropical fruits in midwinter. And it’s getting honed and improved all the time, thanks to digital innovation and the Internet of Things.
“Technology to monitor temperature is not new, but in the last 20 years or so we’ve developed small enough devices that we can track almost anything,” says Donald Ratliff, executive director of the Supply Chain and Logistics Institute at Georgia Tech, where he is also a professor. “We can know in real time whether or not something has been processed and shipped in a way that’s going to be successful.”
That ability has benefited many across the entire planet, says Miguel Gómez, director of the Food Industry Management Program at Cornell University and an expert on international food systems. Berry growers in Chile and Argentina and avocado producers in Mexico, Colombia, and other Latin American countries have experienced enormous growth because of the cold chain. Similarly, India’s growers now export grapes to the European Union, relying on similar methods that deliver both speed and climate control. “They’re doing things better all the time,” Gómez says, “and they’ve learned how to adjust to specific conditions, temperatures, and humidity that these things need to travel those distances.”
In the case of that milk, the cold chain involves several steps, says Ben Brown, assistant professor of professional practice in agricultural risk management at Ohio State University. Milk typically moves from cows through pipes that lead to cooled storage tanks that keep it below 40 degrees Fahrenheit (4 degrees Celsius). Many such tanks are now embedded with smart sensors that immediately report any variation directly to a farmer’s phone or device. The milk is then pumped into refrigerated trucks and driven to processing plants.
There, the milk is tested to ensure it’s been properly chilled and is free of bacteria. Then it’s pasteurized, homogenized, and packaged into containers of various sizes. Finally, the product moves back onto refrigerated trucks for the journey to stores, which can be the trickiest part, because repeatedly opening vehicle doors makes it hard to maintain consistent temperatures. Ratliff says it’s during this so-called last mile—from delivery truck into the store, and then to consumers’ homes—that milk and other cold-chain products are exposed to the greatest temperature variations. The entire process could take from a couple of days to as long as a week.
Some of that has to do with unavoidable realities. With lettuce, for example, the leaves at the top of a shipment will not stay as cool as the greens in the middle of the pile. And while the temperature of bulk containers of milk is easy to track, there’s not yet an economically viable way to track individual gallon or half-gallon units, Ratliff says.
But the system is still remarkable for what it can pull off—for its ability to quickly precool produce and hustle it off on climate-controlled journeys of thousands of miles. Factor in other potential challenges—weather, problems with transportation infrastructure, natural disasters, and other unforeseen events—and the cold chain sometimes gets stretched thin. Early in the pandemic, demand for dairy products such as milk and cheese dramatically shifted when most schools and restaurants closed. Farmers endured a painful stretch of five or six weeks waiting for the supply chain to respond and shift. By May 2020, the industry was able to pivot from pint-sized containers for schools to larger units, and the cold chain adapted, Brown says. Fortunately, most dairy companies were able to change their systems relatively quickly, and many other parts of the cold chain remained viable.
“There were cold-chain logistics issues with getting product packaged differently and to the right spot,” Brown says, “but there was more than enough milk to go around.”
The advent of cold chain management changed the face of farming—and of entire nations. Susanne Freidberg, a professor of geography at Dartmouth, points out that the cold chain helped farming operations grow and specialize. One of its impacts, she says, “was to encourage farms not adjacent to cities to start producing for formerly inaccessible urban markets.”
For example, farmers in New Hampshire could specialize in milk once they were able to load it onto trains to Boston. From there, one of the tools of the cold chain—the refrigerator—helped launch the suburbs, along with the advent of the automobile. “People didn’t need to live near markets and shop daily,” she says. “But of course, the automobile was a big part of that picture.”
The cold chain eventually came to include rail lines that were insulated to keep the milk cold in warm weather and outfitted with heaters to keep it from freezing in winter. Such innovations made possible the creation of farming communities in California, like Petaluma, that have since become suburbs.
As for the future, cold chain logistics will continue to be honed through technology. In a business where delays can mean the loss of food, cold chain companies are deploying digital tools such as route optimization, scanning equipment, and real-time monitoring to improve results. The consumer benefits too. Ratliff points out that restaurant chefs used to have to rely on their eyes and noses to know whether to accept a batch of greens. Now they have access to real-time data that can show the conditions under which it was shipped.
Agriculture experts expect the industry to soon embrace blockchain, a record-keeping technology that allows data to be stored globally on thousands of servers. For food, that means growers can create an entry on a crop of lettuce that can be tracked through the cold chain all the way to its arrival in the consumer’s shopping basket. “If there’s a contamination outbreak, instead of banning the whole product, it can be traced back to the specific farm,” says Brown.
With consumers increasingly interested in knowing the source of their food, this seems like a no-brainer. Brown also imagines a time where customers will be able to scan food products and see the same temperature data that a restaurant chef can see—or information about the farm where a piece of produce was grown. “Maybe there will be a video of the farm where the food came from,” he says.
An entire cottage industry of consultants and solutions has cropped up around today’s cold chain, keen to solve problems and adapt. That leaves the world’s food systems well suited to deal with changes in climate, additional public-health crises, and other challenges that may lie ahead.
Dairy, meat, and poultry are the main beneficiaries of the cold chain, and they all start with a well-raised—and well-fed—animal.