Bump - from just having researched and completing this today. Can't talk about brining turkeys per se, but just finished a brined pork loin roast. Will most definitely brine preparing the next poultry meal, also.
I've found there are a few variables on brining that range from type of meat (some need less time than others), size, leanness of the cut, salt/liquid ratio, type of salt, temperature, and the proper amount of time (and method) to brine.
My understanding is that brining forces the meat to absorb water through osmosis, thereby making it a much more juicy meat (especially with a lean cut like center cut pork loin, for example).
After researching several web pages which appeared to have some level of expertise on the subject, I first figured out that I wanted to brine it overnight, and not just for 7 or 8 hours. I used a mixture of 3/4 cup kosher salt (not table salt, that's heavier than kosher and could throw off the ratio) to a gallon of liquid. Ended up brining for around 18 hours and did not taste over-salted at all.
And as long as we're forcing the meat to absorb, I figured, why not put a little flavor in there while we're at it? Half of the liquid was water and half was chicken stock. To counter the potential for over saltiness, I matched the amount of salt to sweet with a combination of maple syrup, apple jelly, and brown sugar (3/4 cup total). A small amount of peppercorns, thyme, and crushed red pepper (1 Tbsp total or so), and made sure the roast was completely submerged (I learned to cover the roast with a heavy plate to make sure it stays under the whole time).
The other challenge is (of course) cooking it without re-drying it out (easy to dry out a lean cut). I took it out at around 143 degrees and let it rest covered for 15 minutes or so. Damn, that was friggin' delicious. Never had a pork loin so juicy before.
Totally recommend giving this a go. Can't wait to try this with turkey or chicken.
