By Harold McGee
Brining has two initial effects. First, salt disrupts the structure of the muscle filaments. A 3% salt solution (2 tablespoons per quart/30 gm per liter) dissolves parts of the protein structure that supports the contracting filaments, and a 5.5% solution (4 tablespoons per quart/60 gm per liter) partly dissolves the filaments themselves. Second, the interactions of salt and proteins result in a greater water-holding capacity in the muscle cells, which then absorb water from the brine. (The inward movement of salt and water and disruptions of the muscle filaments into the meat also increase its absorption of aromatic molecules from any herbs and spices in the brine.) The meat’s weight increases by 10% or more. When cooked, the meat still loses around 20% of its weight in moisture, but this loss is counter-balanced by the brine absorbed, so the moisture loss is effectively cut in half. In addition, the dissolved protein filaments can’t coagulate into normally dense aggregates, so the cooked meat seems more tender. Because the brine works its way in from the outside, it has its earliest and strongest effects on the meat region most likely to be overcooked, so even a brief, incomplete soaking can make a difference.