Pork shoulder roast is one of those old-fashioned dishes that families used to enjoy for days. After Sunday dinner, there was often enough left for sandwiches, casseroles and pulled pork barbecue. Pork is economical, a good source of protein and can be prepared in a wide variety of ways. Plan this hearty roast for a leisurely family day on a weekend, though, because it may take most of the afternoon to cook.
Pork shoulder roasts are large cuts--1.36 to 2.27kg. for boneless rolled roasts to as much as 10 to 11lbs. for a bone-in roast. A Boston butt (or Boston shoulder) is a rectangular roast cut from the top of the shoulder and is frequently sold boned and rolled. The lower part of the shoulder, also called a fresh picnic or picnic shoulder, is most often sold with the bone in it; a boned picnic roast is called a cushion-style picnic or rolled fresh picnic. When the shank portion of the picnic roast is removed, the roast is called an arm roast. Cooking times for shoulder roasts vary according to size and whether they are bone-in, boneless or rolled roasts. Roasts may take as little as a few hours for a small bone-in Boston butt roast to more than five hours for a 4.08kg. fresh picnic roast.
Shoulder roasts are not tender cuts of pork, so they need to be roasted slowly in a moist environment. Choose a covered roasting pan or roaster oven to keep moisture in during cooking or cover roasts with aluminium foil. Rolled and tied shoulder roasts can be done on a spit or in a barbecue cooker as long as the roast is four or more pounds (smaller roasts will cook too quickly) and the roasting heat can be kept to between 325 and 350 degrees. Unlike loin roasts and tenderloins, which roast best without moisture added, shoulder roasts need moisture to cook evenly and cook out their fat content. Use broth, bouillon or water in the bottom of the pan to establish continuous circulation of moisture. Rolled roasts are more densely constructed roasts that will take longer to cook than bone-in roasts.
Plan 40 to 50 minutes per pound for Boston butt roasts--the top of the shoulder contains more lipids (fats and "gristle") that take longer to break down. A 1.81kg. bone-in Boston butt will take approximately 2 hours and 40 minutes to cook at 325 degrees, but a 1.81kg. boneless Boston butt will take from 3 hours to 3 hours and 20 minutes. Picnic cuts take a bit less time per pound; a 2.27kg. fresh picnic roast will take just about 2 1/2 hours (30 minutes per pound) but a boneless picnic will take up to 3 hours. An arm roast will need 35 to 40 minutes per pound to roast properly. All cooking times can only be approximate because each roast varies in fat content and composition; always check your roast with a meat thermometer to make sure that its inner temperature has reached 170 degrees before taking it out to "rest." It will continue cooking for a few minutes after it leaves the oven.