Delicious Science

Two top chefs combine molecular techniques with traditional Catalan cuisine.

Chef Joan Roca demonstrates the sous vide technique on a piece of Dover sole.
Chef Jordi Roca pours liquid nitrogen into a metal bowl as he makes his chocolate sorbet.
Chef Jordi Roca's chocolate sorbet—white in color after he distilled cocoa beans—was sampled by the audience.

Star Spanish chefs Joan and Jordi Roca know how to put on a show, even when their stage is a Harvard lecture hall. 

As their audience on Monday night watched a giant video screen displaying the famous brothers making cotton candy from sheep’s milk, and then an edible cigar that diners could actually smoke, Jordi poured a container of liquid nitrogen into a metal bowl. As the cauldron bubbled, he added his ingredients and—presto! His chocolate sorbet was made.

But as samples were passed to the crowd in Science Center Hall C, there were hushed gasps: his chocolate sorbet was as white as ice. 

“I wanted to make a dessert that was all white and I thought, ‘White represents purity, and what is more pure than a distillation process?’” said Jordi, who is the chef/owner, along with his brother, of el Celler de Can Roca, currently ranked the number-two restaurant in the world by Restaurant magazine. “I decided to distill cocoa beans—I thought it was very interesting that this whole dessert does not start white but ends up that way. The end result is something you really experience with smell.”

Linking this cooking lesson to science was the main theme of the night: the Roca brothers appeared as part of the School of Engineering and Applied Sciences’s (SEAS) “Science and Cooking” series that examines the relationship between the two fields. The popular Monday night talks are inspired by the General Education course Science of the Physical Universe 27: “Science and Cooking: From Haute Cuisine to Soft Matter Science,” which is being taught this fall by Glover professor of applied mathematics and applied physics Michael Brenner and Mallinckrodt professor of physics and applied physics David Weitz

This year’s lineup boasts an impressive list of world-class chefs, including Ferran Adriá (El Bulli Foundation), David Chang (Momofuku), José Andrés (Minibar), and Wylie Dufresne (WD-50), among others.

Whether concocting their alabaster chocolate sorbet; the cigar-shaped chocolate-coated cake, which has cigar smoke incorporated into fatty molecules to give diners a true Havana experience; intricately designed tapas that use ingredients like fermented soy paste frozen in liquid nitrogen; or caramelized olives served dangling from a bonsai tree, the Roca brothers use scientific methods to produce delicious results. 

During the lecture, they also demonstrated their knowledge of other techniques, such as sous vide—a cooking process in which food is encased in an airtight (typically vacuum sealed) plastic pouch and cooked for a long time at a low temperature, usually below 200 degrees Fahrenheit. The brothers are working with the Catalan government on methods to make this technique easier to teach to home cooks.

The chefs run their three-star Michelin restaurant, located in Girona, Spain, with their brother Josep: Joan runs the kitchen, Josep manages the front of house and wine list, and Jordi provides a sweet finish with his whimsical dessert creations. “Our cuisine is local, but we want our diners to branch out to the universe,” Joan says. “We do Catalan cuisine but we try to use as many scientific techniques as possible to play on the senses—especially senses that play with memory and the way our minds work.”

See a full list of upcoming lectures.

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