Isaac Newton in the Kitchen

Monday, November 19th, 2007

The New York Times calls Harold McGee, author of On Food and Cooking, Isaac Newton in the Kitchen, for his work combining “botany, history, animal husbandry, genetics, chemistry, thermodynamics, physiology and physics” into helpful cooking advice:

For example, although brining the turkey is now part of the Thanksgiving ritual for many cooks, Mr. McGee does not do it. “The bird does become juicier, but it’s just absorbing tap water, not the true juices that make a bird flavorful,” he said. “And the drippings become so salty that you can’t use them.” He says that his own experiments with turkey, though far from complete, show that drying the bird out, rather than infusing it with water, is more likely to make it flavorful and juicy with crisp skin. He unwraps his turkey a day or two before cooking, letting it air-dry in the refrigerator, and then cooks it at high temperature.
But the skin was only golden, not as brown and crisp as we wanted. “Crispness is a matter of heating and dehydrating the proteins,” Mr. McGee said, as he fired up an industrial-size blowtorch and began methodically stroking its blue flame over the turkey. Dissatisfied with the slow results, he switched to a heat gun, whose red-hot coils seemed to give a more concentrated heat. The skin turned from gold to clear and then to bronze, the juices visibly running out of it and through the turkey. “Caramelized has become a popular word since I wrote the first book,” he said. “But everything browned is not caramelized.”

Caramelization, he explained, is what happens to sugar — simple sucrose molecules — exposed to high heat. But the browning that takes place in savory foods like onions, potatoes, celery and turkey skin is a “Maillard reaction,” the explosive meeting of a carbohydrate molecule (which may or may not be a sugar) and an amino acid in a hot, dry environment.

Maillard reactions take place when coffee or cocoa beans are roasted or when a bread crust turns brown. Mr. McGee said: “Maillard reactions contribute even more to the pleasures of eating than caramelization does. But of course it doesn’t sound as good on a menu.”

The alluring scent of Maillard reactions filled the kitchen as Mr. McGee’s pie crust began to brown. Although it is almost impossible to do anything truly new in the kitchen — as Mr. McGee notes, it often turns out that even the most complex flavor combinations were routinely used by Roman cooks — his pie crust method seems revolutionary. “The goal of pie crust is to create thin, even layers of fat and flour,” he said. “That’s what makes them flaky. But the usual method isn’t really optimal for that.”

Instead of using his fingers to rub globs of fat into flour, then dribbling in ice water, Mr. McGee starts with square chunks of cold butter and a pile of flour on a board. With a rolling pin he presses and rolls the butter into the flour, flattening it into thinner and thinner flakes. Occasionally he scrapes the mixture into a bowl and freezes it for five minutes, to keep the butter from melting. Since the gluten is not activated until the water is added, there is no worry about overworking the dough, even though the process can take some time.

Finally, to add the water Mr. McGee fetched a plant mister. “I always found it was hard to get the water evenly into the dough” he said. “So I measured how many sprays of the mister it takes to get half a cup of water — it’s 150, by the way — and I use that to get uniform droplets.” Now working quickly, he lightly squeezed the mister over the dough 50 times, then turned the dough and folded it. After two repetitions the dough just held together. He divided it into two round discs and returned it to the freezer.

Hours later his careful work paid off in a golden-brown crust of unspeakable flakiness and buttery flavor: Mr. McGee’s method means that there is no need to add shortening to ensure a good texture.

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