“For most of my career, I taught classes that people fall asleep in,” said Michael Brenner, professor of applied mathematics and physics at Harvard. But in a lecture Tuesday evening in a packed Salomon 101, Brenner, along with Mark Ladner, executive chef of the Michelin-starred Del Posto restaurant in New York City, entertained the audience by examining the intersection of cooking and mathematics.
The lecture, entitled “Mathematics of Cooking,” was co-hosted by the University’s Institute for Computational and Experimental Research in Mathematics and Johnson and Wales University, Ladner’s alma mater. The event also marked the first time that Brown and JWU have co-hosted an event.
Brenner opened the event by quoting Jean Anthelme Brillat-Savarin, a French lawyer, politician and epicurean: “The discovery of a new dish confers more happiness on humanity than the discovery of a new star.”
Brenner and Ladner maintained a theatrical commentary throughout the lecture, eliciting laughs from audience members and encouraging them to clap whenever a new mathematical formula was displayed on their PowerPoint presentation.
The lecture explored four scientific and mathematical topics that Brenner said are central to cooking — packing, phase transitions, elasticity and diffusion. Brenner explained the mathematical side to each topic with formulas, while Ladner and several assistants performed cooking demonstrations on a long table placed in the middle of the stage.
The first topic, packing, demonstrated the density of various foods. Brenner and Ladner called up three volunteers from the crowd and assigned them to whisk a bowl of egg yolks, a bowl of egg whites and a bowl of water, respectively. The egg whites turned into a solid foam after Ladner’s more practiced hands took over the task of whisking.
Brenner said the eggs contain molecules called surfactants that create bubbles in the foam. To create other kinds of foam that do not taste like eggs, the surfactants can be removed from the eggs and put into the mixture that a chef wants to turn into foam. Brenner held up a bowl of red beet foam as an example. For their participation, all three volunteers were awarded aprons decorated with mathematical formulas.
The second topic of the lecture was phase transitions — the changes among solid, liquid and gas states. Brenner dropped an ice cube onto a hot pan, which quickly melted into a liquid and evaporated into gas. Brenner then cracked an egg into the hot pan to demonstrate that the egg became a solid instead of a gas. Ladner feigned disdain and said “No, no, no” to much laughter from the audience.
Brenner and Ladner used gluten-free pasta to explain elasticity, the third concept. Brenner explained that kneading dough with gluten aligns the glutenin protein molecules, creating stronger bonds. When Brenner and Ladner pulled apart a highly processed dough containing gluten, it stretched out like putty for several feet before the bonds were broken and the dough fell apart.
When they pulled apart an outwardly identical but gluten-free piece of dough, the dough fell apart immediately because it did not have the glutenin proteins to form equally strong bonds. The only substance keeping the gluten-free dough together is xanthan gum, a thickening agent, which does not work as well as gluten.
Next, Brenner displayed a picture of steak, molten chocolate cake, rigatoni and ceviche made of salmon and lime juice. “What do they all have in common?” he asked the audience. All four foods, he said, illustrate diffusion, the fourth topic of the lecture.
Ladner proceeded by heating up a steak for three minutes. As the aroma of steak began filling the room, Brenner said, “This is one of the things that makes cooking better than mathematics, because you get to smell it.” When Ladner finished heating the steak, he showed the audience that it was cooked on the outside but still raw on the inside.
In contrast to the steak, Brenner held up a piece of partially cooked ceviche. Though the ceviche had been cooking for one hour, its cooked layer was not as thick as that of the steak, which had only cooked for three minutes. The reason for this discrepancy is that the ceviche had been cooked with an acid — lime juice — rather than heat.
To conclude the lecture, Brenner and Ladner threw a bowl of green marshmallow Peeps into liquid nitrogen. The peeps instantly froze. After trying the peeps themselves, Brenner and Ladner threw them into the audience, drawing much applause.
Brenner was chosen to give the talk because he had already garnered a reputation due to his popular undergraduate class at Harvard, “Science and Cooking: From Haute Cuisine to the Science of Soft Matter,” said Ruth Crane, assistant director of ICERM.
Peter Lehmuller, associate dean of academic affairs at the College of Culinary Arts atJWU, had the idea of inviting Ladner to the lecture as well, Crane said. Brenner and Ladner had already worked together for Brenner’s Harvard class.
In the question-and-answer session following the lecture, the two speakers were asked to recommend a book about science and cooking. Brenner suggested “On Food and Cooking” by Harold McGee. Ladner recommended the classic cookbook “Joy of Cooking” and New York Times food columnist Mark Bittman’s “How to Cook Everything” as cookbooks that should be in every kitchen.
