In engineering parlance we are faced this Thursday with a very tricky heterogeneous, heat transfer problem. That's a complicated way to say that cooking a turkey well is tricky.
Heat transfer is an essential part of an engineer's work. You can see the results all around you: Open you car's hood and you'll see a radiator. Or, listen to your computer. The optimal position of its cooling fan is found by a heat transfer calculation. The same techniques can be applied to figure out exactly how to cook a turkey.
The problem is this: The breast and the legs cook at different rates. The breast is composed of white meat, and the legs contain dark meat, which has more muscle and connective tissue than the white meat. The goal is to cook the turkey just long enough to break apart this tissue, so that the turkey becomes succulent. That is, the tissue turns to gelatin, which gives a velvety feeling in the mouth.
To achieve this you want the breast to be cooked to 155 degrees Fahrenheit, no more than 160 or it will be too dry. Yet, you want the dark meat to be 180 degrees and above. Under 180 it's unpleasantly chewy and even has a metallic taste. There's the problem: The white breast meat cooks faster than the leg meat, which means it's done well before the dark meat ever reaches the right temperature.
So, how can you avoid, this year, having to pour gravy all over your turkey to disguise its dryness? Here are some engineering, heat transfer cooking tips. First, make sure the turkey is fully thawed. Usually its best to do this in the refrigerator, otherwise the turkey could spoil. The second tip is very controversial: Don't stuff the turkey. It just messes up the heat transfer. By the time the stuffing is fully cooked, the turkey is overcooked by 60 degrees or so.
Third, before cooking cover the breast with an ice pack. As the rest of the turkey comes up to room temperature, the breast will be about twenty degrees cooler. This will solve our holiday heat transfer problem: it'll slow down the cooking rate of the white meat of the breast, making it cook about as fast as the dark meat in the legs.
The last suggestion is obvious, but not always followed: use a thermometer, two if possible. Pull out the turkey when the breast reaches 155 to 160 degrees, and check that at the same time the dark meat is 180 degrees.
Then stop thinking about heat transfer and enjoy your Thanksgiving meal.
[These cooking tips come from Food Scientist Harold McGee. You might check out his book On Food and Cooking for more details.]
Copyright 2004 William S. Hammack Enterprises