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 A roast turkey Lisa Peardon / Getty Images Thanksgiving ResourcesTurkey PhysicsHistory of the turkey: Turkeys are native to North America, called "Indian fowls" in some writings of the 1500s. Around 1519, ships began transporting turkeys back to Spain, thus beginning its migration to Europe. American Benjamin Franklin advocated the turkey as the national bird.
The turkey became prominent in Europe in the 1800s during the holiday season, replacing the goose as the most popular Christmas bird in the latter part of the century. In 1851, Queen Victoria had a turkey in place of her standard Christmas swan. The make-up of a turkey: At the biochemical level a turkey is a combination of approximately 3 parts water to one part fat and one part protein. The majority of meat comes from muscle fibers in the turkey, which are mostly proteins - notably myosin and actin. Because turkeys rarely fly but rather walk, they contain far more fat in their legs than in their breast, which results in the strong differences in texture between these sections of the bird - and the difficulty in making sure that all portions of the bird are properly heated. The science of cooking a turkey: As you cook the turkey, muscle fibers contract until they begin to break up at around 180 degrees Fahrenheit. Bonds within the molecules begin to break down, causing proteins to unravel, and the dense muscle meat to become more tender. Collagen in the bird (one of three protein fibers that attaches muscles to the bone) breaks down into softer gelatin molecules as it unwinds.
The dryness of a turkey is a result of muscle proteins coagulating within the meat, which can result if it is cooked too long. Temperature differentials in cooking a turkey: Part of the problem, as described above, is that the different nature of the light and dark meat in a turkey result in different rates to reach the coagulation of the muscle proteins. If you cook it too long, the breast meat has coagulated; if you don't cook the bird long enough, the dark meat is still tough and chewy.
Harold McGee, a food science writer, indicates aiming for 155 - 160 degrees Fahrenheit in the breast (which concurs with the overall temperature indicated by Roger Highfield), but you want 180 degrees or above in the leg (a distinction Highfield does not address). Heating differentials in cooking a turkey: Since you ultimately want the breast and legs to be different temperatures, the question is how to successfully accomplish this. McGree presents one option, by using ice packs to keep the breast of the bird about 20 degrees lower than the legs while thawing, so that the legs get a "heat start" on the cooking process when they're put in the oven.
Alton Brown, of Food Network's Good Eats, presents another way to establish different heating rates. In his roast turkey recipe, he uses aluminum foil to reflect heat away from the breast, thus resulting in the legs heating faster than the breast. Cooking thermodynamics: Based on thermodynamics, it is possible to make some estimations of cooking time for a turkey. Considering the following estimations, it becomes fairly straightforward:
Traditional cooking times:
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