The " interior " of any muscle or cut meat of a healthy animal is 100% sterile as far as bacteria is concerned. Just like you may have bacteria on your hands and body, that does not mean it is IN your muscles unless you get cut. Bacteria can't and don't migrate into meat... When an animal is slaughter and cut open an Inspector is there and a great deal of precautions are taken to keep bacteria from the guts getting on the meat. It is not Sterile Conditions but this is why processor vac-packed meat has a 4-5 Week self life at temps below 36°, the bacterial count is limited. Now these large Primals get to the Grocery Store. There is some bacteria on the large cut surface and Lots of hands have now handled the vac-pacs and the budgetary and worker educational factors being what they are in store cutting rooms, sanitary conditions of people and equipment, while considered acceptable, is Poor compared to the Processing Facility. As the meat is further cut up in the store, it is possible for bacteria that was on the outside of the meat, packaging, workers hand, body or equipment to be spread to the " outside " of the meat and then to cut surfaces of the roasts, steaks, trays and wrapping equipment when the large cuts are broken down to consumer cuts. This is why a Store Bought Roast has a 5 day shelf life. We now assume because of handling and packaging, there is bacteria on the Roast and if we Grind or Inject or Bone it Out, our further processing can transfer the surface bacteria to the ground, injected or cut meat and follow IT guidelines.If we take an Intact Roast and just go from refer to smoker the bacteria is only on the surface and the 4 hour guideline does not apply.
Dan, mentioned 1/2" of the surface getting to temp but again, Bacteria can't migrate in so the immediate surface is the only concern. Think Searing a Steak...The Bacteria are Instantly killed on the surface, not only after the first 1/2" of each side is cooked! Heck, if that was true, eating a Rare Steak under 1" thick would always cause food poisoning...
The issue with store bought Poultry is because of the high volume mechanized processing it is impossible to maintain the sanitary conditions that are taken in Hand Slaughtered and Gutted Beef and Pork processing operations. Additionally, much of common poultry is now " Enhanced " meaning injected by the processor with a Solution where runoff and excess is collected and recycled throughout the run, thus contaminating the interior of all the breasts and legs of hundreds of birds. This is true of Turkeys, as well, but not the situation with most Duck, Quail and Game Foul processing so these meats even though poultry, can be eaten Rare.
Now, it has been established by the USDA that at 225°F or higher the Smoker heat quickly raises the Surface Temp of a cold hunk of meat in a timely manner, minutes not hours, and is the temp needed to get ground, injected and boned roasts up to or above an IT 140° in around 4 hours where say a 140°F to 180°F smoker temp would have a harder time raising the cold surface temp in short order and would take many many hours to get the interior up safely. I hope this answers some concerns...JJ
Edited by Chef JimmyJ - 2/26/16 at 6:44pm