Come for the Food

In 2008, world renowned Catalan chef Ferran Adrià visited Harvard University to speak with students and the public about the connection between modern science and modern cuisine (1). The buzz he generated, says Sörensen, was overwhelming. Huge lines formed out the door and around the building.

At the time, Harvard was revamping its general education curriculum, searching for subjects that would excite students across disciplines and remain relevant beyond the university gates. Harvard professors David Weitz, a physicist, and Michael Brenner, a mathematician, who together had invited Adrià, saw the wide appeal of the science-through-food approach.

In 2010, they launched the class “Science and Cooking: From Haute Cuisine to the Science of Soft Matter,” complete with guest lectures by Adrià, José Andrés, and a revolving door of other famous chefs (2). In 2011, Sörensen joined the team. Students study everything from the chemical processes at play as sauerkraut ferments to the molecular structure that makes marshmallows elastic. Since its inception, “Science and Cooking” has drawn 100 to 300 students each fall. Sörensen also now teaches a spinoff entirely focused on fermentation as well as online versions of both courses available through edX.

Across the country, a smattering of universities offer similar courses. “When you’re teaching somebody, you have to make a connection” says Keith Symcox, a chemistry instructor at the University of Tulsa, OK, who has taught “Chemistry of Cooking” for 14 years and led a handful of NSF-funded workshops for instructors who’d like to do the same. “[Students] have to have some point of reference, and everybody knows about food.”

Courses typically involve lectures—often cooking demonstrations by chefs who deftly prepare macarons or vinegar shrubs or liquid nitrogen ice cream while instructors offer real-time scientific explanations of the physical and chemical processes taking place.

Labs follow, giving students the opportunity to experiment with class concepts while cooking in a university kitchen or food-safe laboratory. In a typical biology class, students may not be able to watch proteins denature under a microscope. But they can watch an egg solidify when they apply heat and recognize that denatured proteins are the cause. At the end of the semester, many courses culminate in a cooking challenge. At Rice University, in Houston, TX, students across campus vie for tickets to sample the “chemistry of cooking” students’ culinary inventions alongside a panel of judges that includes university faculty and administrators as well as local chefs, explains Lesa Tran Lu, a chemistry lecturer at Rice, who’s taught “The Chemistry of Cooking” since 2014. Dishes are judged on presentation, taste, creativity, technical skill, and the students’ oral presentations on the scientific concepts behind their creations.

Although the ultimate goal is to teach science, many professors also aim to leave students with an appreciation of food. Chemical physicist Patrick Charbonneau at Duke University, in Durham, NC, who this summer is teaching his “Science of Cooking” class for the fourth time, wants to help educate his students’ senses of taste. In one lab, students make emulsions—the term chemists use to describe droplets of one liquid embedded within another liquid. A prime example is mayonnaise, which is essentially tiny droplets of oil suspended within water with an acid and raw egg yolks. “There are so many students who show up and say, ‘I hate mayonnaise,’” he says. “Maybe you do hate mayonnaise. But do you know what mayonnaise is? And once you know what it is, can you better understand what you don’t like about it?”

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Harvard students carefully craft molten chocolate cake in their classroom lab. Image credit: Flickr/Harvard School of Engineering and Applied Science.

Stay for the Science

Some scientific concepts are so central to the kitchen that they’re baked into the syllabi for nearly every science and cooking course. Heat diffusion—the movement of thermal energy through a material—is a popular topic, and not least of all because it can be perfectly illustrated with molten chocolate cake.

Students in Sörensen’s class learn that as heat moves through batter from the outside in, it triggers proteins in the egg to denature and coagulate and starch in the flour to swell. Students can’t see these molecular processes, but they can calculate how quickly heat should move through chocolate cake batter based on its molecular components. They can then bake a molten chocolate cake, slice it open, and test whether heat diffused at the rate that they expected. If students don’t apply heat for long enough, the solidified outer shell is too thin and won’t hold. If they bake the cake for too long, the center becomes solidified and the cake loses its characteristic gooey interior. “If you want your cake to be good,” says Sörensen, “this is the physics, this is the science to make that happen.”

Another common topic is the foam, a term for tiny gas bubbles dispersed in a solid or liquid. At Rice University, students learn tricks for making one classic foam, the macaron, from local chef Sandia Horng of Bite Macarons. They’re taught, for example, that super fine sugar, rather than granulated sugar, helps add body and retains moisture without disrupting the air bubbles as much. A few years ago, a group in Tran Lu’s class incorporated the technique into their final project—a dill macaron with a lemon black pepper cream cheese filling and gravlax salmon that the students cured themselves.

Students also frequently study spherification—a method for turning liquid droplets into gelatinous balls that can resemble caviar (3). The technique hinges on a chemical reaction that occurs when a chef mixes any edible liquid that doesn’t already contain calcium with sodium alginate and then submerses drops of the mixture into a bath of calcium lactate.

After studying spherification in Charbonneau’s class last semester, rising sophomore Evan Finley, a liberal arts student, crafted a final project with an Italian cuisine-inspired riff on a traditional Japanese sushi roll, trading seaweed for prosciutto. Instead of salmon roe, he used cantaloupe juice, spherified into balls. Working from his family’s kitchen because of the coronavirus school closure, Finley spent an hour transferring his cantaloupe mixture into the calcium lactate bath with an eye dropper until he had about 200 balls, just enough to cover the sushi roll. On a Zoom call with his class, he took one bite and the sushi fell apart. “The execution was not what I imagined it to be,” Finley laughs. But the taste? “If a real kitchen decided to make this dish,” he says, “I think it could be a real hit.”

A Chef Assist

Much of the excitement surrounding Harvard’s course centers on celebrity chef appearances.

When chefs cook in class, “there is something of the wow factor that draws you in,” says Sörensen. But the chefs don’t always fully understand the science underlying their inventive methods, leaving room for exploration along with students.

Last year, chef Selassie Atadika from a restaurant in Ghana called Midunu cooked a dish using potash, a natural potassium containing compound, one that Sörensen had never encountered as a thickener used in combination with oil. Sörensen encouraged a group of students to study the chemistry underlying how potash thickened the palm oil in the dish through curdling. “We were trying to figure out why only certain types of oil get curdled by potash,” explains Chanel Varney, who graduated this past spring with a degree in human developmental and regenerative biology. The team added potash to five different cooking oils at a range of temperatures and measured how much of the solution thickened into curdles. A definitive explanation proved elusive. But Varney suspects that palm oil may curdle more readily than others because of its long chains of saturated fats that readily tangle in response to potash’s extremely basic pH level. “We walked away saying it’s not the absolute content of saturated fats, but maybe it’s the long chain concentration,” she says.

At Rice, students also work directly with campus and Houston-area chefs, including chef Johnny Curet, the campus dining director, who co-teaches the course with Tran Lu. Chef Nick Fine and his Underbelly Hospitality restaurant group’s owner, award-winning chef Chris Shepherd, give demonstrations, advise students on independent research, and judge final projects.

Tran Lu and Rice students also help the chefs at Underbelly Hospitality explore culinary quandaries. “We’ll say, ‘This is a problem that we’re having. Can you help us figure this out?’” says Fine. The chefs, for example, had been importing fermented duck eggs known as “hundred-year eggs.” They wanted to learn how they might make their own.

Tran Lu connected Fine and Shepherd with Rice chemistry lecturer Caroline McNeil, who assigned the task to a small student group in her “Introduction to Scientific Research Challenges” course. Similar to published recipes, the students proposed using alkaline solutions, zinc oxide, and tea leaves to denature proteins and create the desired color and texture. Following the students’ advice, the chefs then began serving Texas-made, hundred-year eggs at their restaurant.

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Rice University instructor Lesa Tran Lu teaches her class alongside award-winning chef Chris Shepherd. Image credit: Jeff Fitlow (Rice University, Houston, TX).

Cooking (and Science) for Life

Tran Lu, who also teaches general chemistry, has noticed that certain concepts are easier to grasp in the kitchen. Her cooking class students, having mixed and heated or cooled ingredients, quickly learn the intermolecular principles of colligative properties—the way that properties such as boiling or freezing point change depending on how much solute is in a solution.

Sörensen hopes that students who cook their way through science lessons are also more likely to retain those lessons. She often hears students talking about how they told friends or family members about a cooking lab. “The whole idea with retention is that you repeat it a number of times and it sticks better,” says Sörensen. “You can imagine that by doing [science] within a topic that lends itself to retelling, that maybe you increase retention.”

Molly Leavens, who graduated from Harvard in fall 2019 with a degree in food and the environment, took the science and cooking course four years ago, yet readily rattles off a list of foods, from black garlic to oatmeal cookies, whose deliciously browned exteriors she says would not be possible without the Maillard reaction—the interaction of a free amino group like an amino acid with certain sugars like monosaccharides.

Regardless of whether cooking helps students retain science, Charbonneau considers his class a success if students, many of whom are not science majors, leave school with a positive impression of scientific disciplines. “I hope that ten years down the road, when they look at the importance of science in, say, predicting epidemics, they are more receptive to it,” he says, “having had a good last experience in science.”

This past spring semester, the coronavirus pandemic forced students to take all of these lessons out into the world—or at least into their parents’ kitchens—sooner than expected. Even after every other chemistry lab at his university had shut down, Symcox’s students kept cooking—making their own yogurt, key lime pie, and eggnog, for example, in an exploration of the pH required to make gels. He put the recipes online and asked students to send in pictures of their creations that he then used during online lectures. “Each one of you has to make the dishes at home,” he told his students. “Feel free to have your parents help you eat it.”