I don't know why people just don't brine with lots of flavor. I do marinate my turkey instead of brining though.
excerpt from a Fine Cooking article:
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.
Whatever you're brining, remember to rinse the meat or fish well afterward to remove any surface salt. Properly brined meat shouldn't taste salty, just very juicy with good flavor. But do reduce the amount of salt called for in the recipe; that is, don't add salt until the dish is at a point where you can taste it and judge
There is a commonly held belief that soaking a tough cut of meat in a marinade will make it tender. Sadly, this just isn't true much of the time. While some marinades are very successful at adding flavor to meat, chicken, and fish, they are, with one exception, a disaster at tenderizing.
The two most popular types of marinades are acidic (made with citrus, vinegar, or wine) and enzymatic (made with ingredients such as pineapple and papaya). Although both types work primarily on the surface of the food, they lead to different results: highly acidic marinades can actually toughen food, while enzymatic marinades can turn the surface of the food to mush. For true tenderizing, the most effective marinades are those that contain dairy products.
Acidic marinades "denature" proteins. Imagine the protein in raw meat, chicken, or fish as individual units of coiled ribbon, with bonds holding each coil in a tight bundle. When these proteins are exposed to an acidic marinade, the bonds break and the proteins unwind. Almost immediately, one unwound protein runs into another unwound protein and they bond together into a loose mesh. (This is the same thing that happens when proteins are exposed to heat.)
I think marinades can make certain food mushy while brining won't.
Interesting cuz I don't brine much. I do a lot of marinating but I do marinate a lot of chicken and pork but these are usually marinated for a few days. Steak when marinated is usually overnight but not in an acidic one.