I am cooking approximately 30 lbs of Boston butt pork roast. (One roast is a little over 15 lbs and the other is a little over 16 lbs.) Should I cook the roasts together in one big roaster at about 250 degrees or separate them? I am doing pulled pork for a crowd. How long do you think this might take?
You can keep them together, but I would recommend budgeting a very long time for cooking. In my opinion, your better bet would be to slow roast them in the oven, with some air space between the two roasts. I would also consider cutting each roast in half. Four 7-8 pound pork butts will cook much faster than two 15-16 pound ones.
I recommend roasting them separately (although at the same time) for one main reason: More surface area means more of the delicious brown crispy bits on the surface.
It will also take less time, probably, than if they are piled together or if you get an entire shoulder, but that is less important.
I disagree respectfully with MandoMando: pork butt cooked low and slow does not require brining in any way. It has sufficient fat and gelatin to be quite delectable after cooking.
I should add in terms of cooking time:
- If braising, 3-4 hours, probably
- If low roasting, 3-12 hours, depending on temperature, most likely in the 4-5 hour range at 250 since that is not as fast as braising at transferring heat energy to the food object
In either case, you will know it is done when it pulls easily. This is not a case where final internal temperature (you want about 180 F) is the goal; you also need time at temperature to covert the collagen in the pork to gelatin to give it that luxurious texture.
The time is determined by thickness of the roast more than the weight. It takes longer for the heat to penetrate depth.
I would do them separately for less humidity in the roaster and lower load on the roaster (unless your roaster is so big that it doesn't care). Crowding ovens and roasters isn't optimal. Patting them dry and rubbing oil on them also helps the process.
Stick one of those in-oven digital thermometer alarms in the center of the roast and be done with the time guessing and safety concerns. That way you can pull them out right when they're perfect. But if I were to guess, I'd say about 4-5hrs @250F possibly more.
Consider brining the meats for 12-24hrs in %6 salt-water brine to minimize juice loss and let the roasts rest (relax the protein) for about 30 minutes when they come to out before you cut/pull them.