Roasted turkey breast, sautéed pork chops, and stir-fried shrimp all tend to suffer a common fate when they're cooked even a few minutes longer than necessary: they get dry and tough. Actually, any kind of meat or fish will taste like shoe leather if it's severely overcooked, but turkey, pork, and shrimp are particularly vulnerable because they're so lean. Luckily, there's a simple solution (literally) for this problem. Soaking these types of leaner meats in a brine—a solution of salt and water—will help ensure moister, juicier results.
For more turkey know-how, see our 21 Tips for Better Turkey and visit The Guide to Thanksgiving Dinner to watch videos demonstrating how to brine a turkey using a wet-brine method and a dry-brine method.
How a brine works
Moisture loss is inevitable when you cook any type of muscle fiber. Heat causes raw individual coiled proteins in the fibers to unwind—the technical term is denature—and then join together with one another, resulting in some shrinkage and moisture loss. (By the way, acids, salt, and even air can have the same denaturing effect on proteins as heat.) Normally, meat loses about 30 percent of its weight during cooking. But if you soak the meat in a brine first, you can reduce this moisture loss during cooking to as little as 15 percent, according to Dr. Estes Reynolds, a brining expert at the University of Georgia.
Brining enhances juiciness in several ways. First of all, muscle fibers simply absorb liquid during the brining period. Some of this liquid gets lost during cooking, but since the meat is in a sense more juicy at the start of cooking, it ends up juicier. We can verify that brined meat and fish absorb liquid by weighing them before and after brining. Brined meats typically weigh six to eight percent more than they did before brining—clear proof of the water uptake.
Another way that brining increases juiciness is by dissolving some proteins. A mild salt solution can actually dissolve some of the proteins in muscle fibers, turning them from solid to liquid.
Of all the processes at work during brining, the most significant is salt's ability to denature proteins. The dissolved salt causes some of the proteins in muscle fibers to unwind and swell. As they unwind, the bonds that had held the protein unit together as a bundle break. Water from the brine binds directly to these proteins, but even more important, water gets trapped between these proteins when the meat cooks and the proteins bind together. Some of this would happen anyway just during cooking, but the brine unwinds more proteins and exposes more bonding sites. As long as you don't overcook the meat, which would cause protein bonds to tighten and squeeze out a lot of the trapped liquid, these natural juices will be retained.
How long to brine depends on the size and type of meat you've got. Larger meats like a whole turkey require much more time for the brine to do its thing. Small pieces of seafood like shrimp shouldn't sit in a brine for more than half an hour. In fact, any meat that's brined for too long will dry out and start to taste salty as the salt ends up pulling liquid out of the muscle fibers. (Be sure not to brine meats that have already been brined before you buy them, such as "extra-tender" pork, which has been treated with sodium phosphate and water to make it juicier.)