It takes approximately 100 minutes to cook a 5-pound boneless pork loin roasted at 325 F. The USDA recommends that all whole cuts of meat be cooked to an internal temperature of 145 F and then allowed to rest for an additional 3 minutes.
Another roasting method, which takes approximately 90 minutes, involves browning the roast at 450 F for 10 minutes and then reducing the oven temperature to 250 F for the remainder of the cooking time. After cooking, cover the roast with foil, and let it rest for an additional 15 minutes. Roasts can be seasoned with salt, pepper, fresh or dried herbs and spices. To keep the meat moist, place the roast in the pan with the fat side on the top.