Our task was simple enough: Find the most frugal way to cook pasta, and explain the science behind it.
But there was the Nobel laureate’s plan to consider, as well as the opinions of Michelin-starred chefs. There were only a few elements—pot, water, pasta—but many ways to vary them, along with heat and time. There were ecological considerations, cost breakdowns—and, constantly, puns boiling over. All part of demonstrating science’s real-world applications.
As often happens with scientific investigations, the inspiration came from something else entirely: a hummingbird hawk-moth using its slender proboscis to feed. As a physicist with a particular interest in all things soft or fluidlike, I was intrigued: How does the moth suck sticky nectar up that flexible tube?
So I challenged two students, Mia London and Ross Broadhurst, to scale up the problem using simple components. They chose bucatini, a long hollow pasta, and cunningly controlled its stiffness through cooking time. Success! They were indeed able to reproduce the conditions of proboscis drinking. End of story. Or so we all thought …
A few months later we were back in the lab, bubbling up more bucatini—because we’d plunged into a heated debate over the “best” way to cook pasta.
It began about a year ago, after Giorgio Parisi, a Nobel Prize–winning Italian physicist, shared architect Alessandro Busiri Vici’s Facebook post on an economical way to cook their nation’s favorite carb. Cut off the heat halfway through cooking and let the hot water finish the job, Busiri Vici advised. But “keep the cover always” on, Parisi emphasized, for insulation and to prevent heat loss from evaporation.
Even though energy and other living costs had soared in much of Europe, the thrifty suggestion Parisi and Busiri Vici shared stirred up angry responses from fellow Italians. “It’s a disaster,” raged renowned chef Luigi Pomata, admonishing that Parisi and other physicists should keep well away from the kitchen. Michelin-starred chef Antonello Colonna said customers in his restaurant would never tolerate the rubbery results of the recommended method.
But Colonna mentioned another cost-saving approach: the “cold water method,” endorsed by American chef Alton Brown. Defying all culinary traditions, this starts with the pasta in cold water and brings everything to the boil together.
Others joined the social media frenzy, tossing in their opinions, insults, and recipes. Despite Nobel laureate Parisi’s expertise—his theories uncover patterns in complex systems, from molecules to memory, from the flocking of birds to the spinning of planets—even he might not have predicted the reactions to his well-intentioned post.
What is pasta, in scientific terms? What happens when we cook dried pasta? And most important in the debate about the most delectable frugal-cooking techniques: Who’s right?
The answer to question one is simple. Dried pasta is made by adding H2O to ground durum, a subspecies of Triticum turgidum; that is, by shaping and drying a mixture of water and semolina flour milled from durum wheat.
The answer to question number two: When we cook dried pasta, two processes take place, both pretty straightforward. First, it must rehydrate and soften by absorbing water. It does this by diffusion, the same principle as when perfume’s scent spreads through a room. Driven by diffusion, boiling water molecules will penetrate to the center of a strand of typical-thickness spaghetti in about 10 minutes. Interestingly, diffusion slows down over time; in pasta twice the typical-spaghetti thickness, the water would take 40 minutes. This explains why you find chewy bits when strands get stuck together in the pot: There simply wasn’t time for water to diffuse to the center of the clumps.
Second, the pasta must cook, which requires heat. Like the water, heat also diffuses into the pasta, swelling the proteins, breaking down starch grains, and making everything edible.
Online tutorials, package instructions, and ChatGPT generally agree on a standard method to cook pasta. Per serving: Drop three ounces of pasta into a quart of vigorously boiling water with a pinch of salt. Add oil, suggest some. Stir occasionally to stop sticking (or don’t). Cook for around 10 minutes, enough time for both heat and water to wiggle their way in. Drain, rinse (or don’t rinse). Add sauce (or don’t). Serve.
Minor changes in preparation may alter the taste but won’t affect the cost of cooking, because it all boils down to the heating. The cost depends on how much energy is needed to heat the pot, water, and pasta to 212°F—and then, how much more energy is needed to keep it boiling for 10 minutes. To calculate precisely, we need to know the price of energy, whether you’re using electricity or gas, and the type of stove; the metal the pot’s made of, its thickness and weight, and the energy needed to heat it …
Yes, we did the calculations. Mia, Ross, and I cooked pasta by the standard method, over and over. We calculated the outcomes for various combinations of pot, stove, and energy source, and came up with an average cooking cost: about a dime a portion. Heating the water uses most of the energy; heating the pasta accounts for only one percent of it.
Across the United States, some six billion pounds of pasta are twirled and slurped every year, costing an estimated three billion dollars to cook. On a scale like that, even a small energy savings would make a big difference.
Let’s review the possibilities.
Parisi and Busiri Vici’s suggestion halves the energy used in the cooking stage and saves three of the 10 cents a portion. The cold water method of chef Brown also reduces the cooking stage, likewise saving around three cents.
Using less water will cut cooking costs too. Harold McGee, author of On Food and Cooking, encouraged New York Times readers years ago to try both a cold start and reducing the water to a third. He warned the approach “requires more attention” and regular stirring. But I reckon it would save some six of the 10 cents.
On SeriousEats.com, chef J. Kenji Lopez-Alt urges an even more dramatic method. He drops the pasta into minimal boiling water, stirs when it resumes boiling, then turns off the heat, covers the pot, and waits 10 minutes. Drain, eat—and save eight cents a portion, by my calculation.
Then Mia and Ross entered this culinary-science contest, and did not disappoint. They tried an alternative method—presoaking—whose success lies in separating the processes of rehydration and cooking. Though water diffusion is much slower at room temperature, after two hours the pasta becomes soft. Once drained, it can be heated briefly in a pot with water or sauce to finish cooking. By avoiding other methods’ generation of steam that escapes and hot water that’s thrown away—all wasted energy—this approach saves more than nine cents a portion. (The website of the Exploratorium, San Francisco’s science museum, has an article, a recipe, and a video about the method.)
(Explore the top 10 science museums in the United States.)
You might legitimately ask: Why are university scientists perfecting the cooking of pasta? Or the blowing of soap bubbles? Have they not heard about the threat of climate change or the challenges of sustainable energy production? Yes, we have. But to tackle these global issues requires a wider diversity of scientific voices and the support of a public that is both curious about the discoveries of science and trusting in its processes.
By lifting the lid on the science of everyday life, we hope to prepare many others to thrive in an increasingly technological world—and to use their awareness and passion to protect the planet.
This story appears in the September 2023 issue of National Geographic magazine.