Pork loin should be cooked for approximately 30 minutes per pound in an oven that has been preheated to 350 degrees. A good way to ensure that a pork loin is properly cooked is to use a meat thermometer. The meat will be done when the thermometer reaches a temperature of 155 to 165 degrees.
The thermometer should be inserted into the thickest part of the pork loin and should not be touching any part of the bone. This allows for an accurate reading. Browning the pork loin before cooking it will help seal in its juices, making it more flavorful.