Q. I'm confused. I get different answers to this question from different grocery stores. Is the Boston Butt taken from the hind quarters or shoulder area of the pig? Also why is some called Boston Butt and others called just shoulder roast? Are they one of the same cut of meat? Finally why is some of the pork roast reddish color and others are lighter in color, and how do you shop for a good pork roast?
Slow down. Take a deep breath. One pig question at a time, please. Different cuts of meat often go by different names in different parts of the country, but anyone involved in selling pork should be able to tell
whether the pig is coming or going.
The Boston butt, despite the rather inelegant and inaccurate reference, comes from the upper front shoulder of the pig. Commercial cuts from the Boston butt include the blade Boston roast, the blade steak, and the shoulder roll. The lower part of the front shoulder extending down to the hock is generally called the picnic shoulder, and cuts from that can be called arm picnic roast, arm roast, arm steak, picnic roast. The term shoulder roast is a little vague, but certainly comes from the front half of the pig, and probably the upper shoulder.
Why some meats not just pork are lighter or darker is a fairly complicated subject. In his very interesting but fairly scholarly book The Science of Cooking (Canada, UK), Peter Barham explains that several factors contribute to the color of meat. Haemoglobin, a molecule that carries oxygen around a body in its blood when it is alive, is absorbed in muscle, contributing a bit of red color. Muscles that are heavily used may not be able to get enough oxygen from the blood, and must resort to oxygen stored in myoglobin (protein) molecules. Both haemoglobin and myoglobin are red when carrying oxygen. Finally, there are two types of a protein called myosin found in a muscle. One, again depending on how much use the muscle sees, has more need of the oxygen stored in myoglobin, and will be darker as a result.
Barham explains that turkeys, which stand around a lot but hardly ever fly, have dark leg meat but breasts that are white. Game animals, which tend to use all their muscles, are essentially all dark meat, while domesticated animals generally have a mix of both light and dark. In terms of cooking, dark meat generally has more flavor, but, because those muscles were more actively exercised, tends to be tougher. Lighter meats tend to be more tender but have less flavor.
Now, you can imagine that the shoulder muscle of a pig gets plenty of use, so it tends to be on the red side, full of flavor, and fairly tough. A sirloin roast, from the relatively relaxed upper back, is whiter, more tender, and less flavorful. If you go with the shoulder, you might like to consider Shirley Corriher's famous Fall-Apart-Tender Slow-Cook Pork Roast recipe, which is cooked very slowly in liquid (braised). A more tender loin could simply be roasted in the oven at 375°F (190°C) for an hour or so, depending on the size. But it should be marinated, basted, studded, filled, or sauced before, during, or after cooking to make up for its general lack of flavor.