SCIENCE AND CULTURE

Universities move science labs to the kitchenCarolyn Beans, Science Writer

Coronavirus school closures left many science profes-sors scrambling for new ways to teach concepts tradi-tionally explored in the lab. Not so for Pia Sörensen, asenior preceptor in chemical engineering and appliedmaterials at Harvard University in Cambridge, MA. Shebreathed easy, knowing that even without advancedscientific instruments, her students could still access theonly laboratories they really needed: their own kitchens.

Sörensen is one of a small group of universityteachers who explore the science of matter throughthe art of cooking. Although often instructed with abig assist from professional chefs, these courses aim

to elucidate scientific concepts that underlie all kitchencreations—from the humblest of eggs to the most ele-vated of foams. “Food is this thing that draws people inand it’s something that people naturally do,” says Sör-ensen. “They are doing science and they are doing ex-periments. They’re just doing them in their kitchens.”

By letting students experiment in the kitchen, ratherthan the lab, instructors aim to draw more students toscience. And by serving up a heavy portion of chem-istry, math, and physics alongside mouthwatering labs,they hope to hold that interest in science—and food—for a lifetime.

Come for the FoodIn 2008, world renowned Catalan chef Ferran Adriàvisited Harvard University to speak with students andthe public about the connection between modernscience and modern cuisine (1). The buzz he gener-ated, says Sörensen, was overwhelming. Huge linesformed out the door and around the building.

At the time, Harvard was revamping its generaleducation curriculum, searching for subjects thatwould excite students across disciplines and remainrelevant beyond the university gates. Harvard profes-sors David Weitz, a physicist, and Michael Brenner, amathematician, who together had invited Adrià, sawthe wide appeal of the science-through-food approach.

In 2010, they launched the class “Science andCooking: From Haute Cuisine to the Science of SoftMatter,” complete with guest lectures by Adrià, JoseAndres, and a revolving door of other famous chefs(2). In 2011, Sörensen joined the team. Students studyeverything from the chemical processes at play assauerkraut ferments to the molecular structure thatmakes marshmallows elastic. Since its inception, “Scienceand Cooking” has drawn 100 to 300 students eachfall. Sörensen also now teaches a spinoff entirely fo-cused on fermentation as well as online versions ofboth courses available through edX.

Across the country, a smattering of universitiesoffer similar courses. “When you’re teaching some-body, you have to make a connection” says KeithSymcox, a chemistry instructor at the University ofTulsa, OK, who has taught “Chemistry of Cooking” for14 years and led a handful of NSF-funded workshops

Students in Harvard’s “Science and Cooking” class insert temperature probesinto molten chocolate cake batter to study how heat diffuses through the cakeas it bakes. Image credit: HarvardX/Amanda Justice.

Published under the PNAS license.First published August 12, 2020.

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for instructors who’d like to do the same. “[Students]have to have some point of reference, and everybodyknows about food.”

Courses typically involve lectures—often cookingdemonstrations by chefs who deftly prepare macaronsor vinegar shrubs or liquid nitrogen ice cream whileinstructors offer real-time scientific explanations of thephysical and chemical processes taking place.

Labs follow, giving students the opportunity toexperiment with class concepts while cooking in auniversity kitchen or food-safe laboratory. In a typicalbiology class, students may not be able to watchproteins denature under a microscope. But they canwatch an egg solidify when they apply heat and rec-ognize that denatured proteins are the cause. At theend of the semester, many courses culminate in acooking challenge. At Rice University, in Houston, TX,students across campus vie for tickets to sample the“chemistry of cooking” students’ culinary inventionsalongside a panel of judges that includes universityfaculty and administrators as well as local chefs, ex-plains Lesa Tran Lu, a chemistry lecturer at Rice, who’staught “The Chemistry of Cooking” since 2014.Dishes are judged on presentation, taste, creativity,technical skill, and the students’ oral presentations onthe scientific concepts behind their creations.

Although the ultimate goal is to teach science,many professors also aim to leave students with anappreciation of food. Chemical physicist PatrickCharbonneau at Duke University, in Durham, NC, whothis summer is teaching his “Science of Cooking” classfor 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 oneliquid embedded within another liquid. A primeexample is mayonnaise, which is essentially tiny dropletsof oil suspended within water with an acid and raw eggyolks. “There are so many students who show up andsay, ‘I hate mayonnaise,’” he says. “Maybe you do hatemayonnaise. But do you know what mayonnaise is? Andonce you know what it is, can you better understandwhat you don’t like about it?”

Stay for the ScienceSome scientific concepts are so central to the kitchenthat they’re baked into the syllabi for nearly everyscience and cooking course. Heat diffusion—themovement of thermal energy through a material—is apopular topic, and not least of all because it can beperfectly illustrated with molten chocolate cake.

Students in Sörensen’s class learn that as heatmoves through batter from the outside in, it triggersproteins in the egg to denature and coagulate andstarch in the flour to swell. Students can’t see thesemolecular processes, but they can calculate howquickly heat should move through chocolate cakebatter based on its molecular components. They canthen bake a molten chocolate cake, slice it open, andtest whether heat diffused at the rate that theyexpected. If students don’t apply heat for longenough, the solidified outer shell is too thin and won’thold. If they bake the cake for too long, the centerbecomes solidified and the cake loses its characteristicgooey interior. “If you want your cake to be good,”

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

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says Sörensen, “this is the physics, this is the scienceto make that happen.”

Another common topic is the foam, a term for tinygas bubbles dispersed in a solid or liquid. At RiceUniversity, students learn tricks for making one classicfoam, the macaron, from local chef Sandia Horng ofBite Macarons. They’re taught, for example, that superfine sugar, rather than granulated sugar, helps addbody and retains moisture without disrupting the airbubbles as much. A few years ago, a group in Tran Lu’sclass incorporated the technique into their final project—a dill macaron with a lemon black pepper creamcheese filling and gravlax salmon that the studentscured themselves.

Students also frequently study spherification—amethod for turning liquid droplets into gelatinousballs that can resemble caviar (3). The techniquehinges on a chemical reaction that occurs when a chefmixes any edible liquid that doesn’t already containcalcium with sodium alginate and then submersesdrops of the mixture into a bath of calcium lactate.

After studying spherification in Charbonneau’sclass last semester, rising sophomore Evan Finley, aliberal arts student, crafted a final project with anItalian cuisine-inspired riff on a traditional Japanesesushi roll, trading seaweed for prosciutto. Instead ofsalmon roe, he used cantaloupe juice, spherified intoballs. Working from his family’s kitchen because of thecoronavirus school closure, Finley spent an hourtransferring his cantaloupe mixture into the calciumlactate bath with an eye dropper until he had about200 balls, just enough to cover the sushi roll. On aZoom call with his class, he took one bite and the sushifell apart. “The execution was not what I imagined it tobe,” Finley laughs. But the taste? “If a real kitchendecided to make this dish,” he says, “I think it couldbe a real hit.”

A Chef AssistMuch of the excitement surrounding Harvard’s coursecenters on celebrity chef appearances.

When chefs cook in class, “there is something ofthe wow factor that draws you in,” says Sörensen. Butthe chefs don’t always fully understand the scienceunderlying their inventive methods, leaving room forexploration along with students.

Last year, chef Selassie Atadika from a restaurant inGhana called Midunu cooked a dish using potash, anatural potassium containing compound, one thatSörensen had never encountered as a thickener usedin combination with oil. Sörensen encouraged a groupof students to study the chemistry underlying howpotash thickened the palm oil in the dish throughcurdling. “We were trying to figure out why only cer-tain types of oil get curdled by potash,” explainsChanel Varney, who graduated this past spring with adegree in human developmental and regenerativebiology. The team added potash to five differentcooking oils at a range of temperatures and measuredhow much of the solution thickened into curdles. Adefinitive explanation proved elusive. But Varneysuspects that palm oil may curdle more readily thanothers because of its long chains of saturated fats thatreadily tangle in response to potash’s extremely basicpH level. “Wewalked away saying it’s not the absolutecontent of saturated fats, but maybe it’s the long chainconcentration,” she says.

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

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

Tran Lu connected Fine and Shepherd with Ricechemistry lecturer Caroline McNeil, who assigned thetask to a small student group in her “Introduction toScientific Research Challenges” course. Similar topublished recipes, the students proposed using al-kaline solutions, zinc oxide, and tea leaves to dena-ture proteins and create the desired color andtexture. Following the students’ advice, the chefsthen began serving Texas-made, hundred-year eggsat their restaurant.

Cooking (and Science) for LifeTran Lu, who also teaches general chemistry, has no-ticed that certain concepts are easier to grasp in thekitchen. Her cooking class students, having mixedand heated or cooled ingredients, quickly learn theintermolecular principles of colligative properties—the way that properties such as boiling or freezing

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

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point change depending on how much solute is ina solution.

Sörensen hopes that students who cook their waythrough science lessons are also more likely to retainthose lessons. She often hears students talking abouthow they told friends or family members about acooking lab. “The whole idea with retention is that yourepeat it a number of times and it sticks better,” saysSörensen. “You can imagine that by doing [science]within a topic that lends itself to retelling, that maybeyou increase retention.”

Molly Leavens, who graduated from Harvard infall 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 garlicto oatmeal cookies, whose deliciously browned ex-teriors she says would not be possible without theMaillard reaction—the interaction of a free aminogroup like an amino acid with certain sugars likemonosaccharides.

Regardless of whether cooking helps students re-tain science, Charbonneau considers his class a suc-cess if students, many of whom are not science majors,leave school with a positive impression of scien-tific 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,” hesays, “having had a good last experience in science.”

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

1 S. Sweeney, “In good taste” The Harvard Gazette (2010). https://news.harvard.edu/gazette/story/2010/09/in-good-taste/. Accessed22 May 2020.

2 P. M. Sörensen, O. G. Mouritsen, Science education and public understanding of science via food, cooking, and flavour. Int. J. Gastron.Food Sci. 15, 36–47 (2019).

3 P. Lee, M. A. Rogers, Effect of calcium source and exposure-time on basic caviar spherification using sodium alginate. Int. J. Gastron.Food Sci. 1, 96–100 (2012).

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