A busy mother preparing a Thanksgiving meal may be tempted to partially roast a turkey in advance the day before and then complete cooking the bird on the day of the meal. This, however, should not be attempted, as interrupting the cooking of turkey that hasn't been completely cooked can enhance the opportunity for harmful bacteria to grow and lead to potential health risks.
Cooking and Browning
The U.S. Department of Agriculture's Food Safety and Inspection Service is unequivocally clear in recommending that you never partially cook or brown a turkey and finish cooking it later. This method of cooking can create the perfect environment for bacterial growth; only fully cooking the bird will destroy all bacteria present. If partially cooked food is held — even if it is refrigerated — bacteria will grow, and subsequent cooking may not be enough to eradicate all bacteria.
Partial Cooking in a Micowave
It's safe to thaw or partially cook turkey in a microwave, but only if you continue to cook it immediately afterward; a turkey that has been partially cooked in a microwave should not be held for later cooking, for the same reasons outlined above. When roasting a turkey, the best way to determine whether it's fully cooked is to use a meat thermometer. When the thigh meat reaches an internal temperature of 180 degrees F and the breast meat is 170 degrees F, the turkey is fully cooked and safe to eat.
Best Thawing Methods
If you're going to be cooking a frozen turkey, the best way to thaw it is to let the bird thaw in the refrigerator. This can take awhile, as a full day in the refrigerator is required for every five pounds to thaw. If you need to thaw your turkey faster, place the bird in a cold water bath, which typically takes about a half-hour per pound. Keep the water running if possible or change the water regularly to prevent it from freezing. Never try to thaw a turkey by letting it sit unrefrigerated at room temperature, as this will cause bacteria to grow.
Reheating
Although you should never partially cook a turkey and complete cooking later, you can cook the bird ahead of time and reheat the meat later. After removing the fully cooked turkey from the oven, let it sit for 30 minutes to allow the juices to settle into the meat before carving. Layer the carved meat in a baking dish and cover with aluminum foil for reheating. Breast meat is more likely to dry out when reheated, so place the breast meat on the bottom of the dish. It may also be a good idea to cover the meat with gravy or some turkey stock in order to keep the meat moist during reheating.