Brining doesn't impart the intense flavors to ribs that a marinade does, but it isn't supposed to. Brining primarily flavors meat with salt -- a most effective flavor enhancer on its own. The process in which it does so also increases the moisture within the meat by as much as 10 to 15 percent -- a friend with benefits, you could say. Beer is mostly water, making it a capable vehicle to transport salt and moisture into the meat during soaking, and alcohol is a natural solvent so it helps pull the flavor from herbs and spices. Beer-based brines do everything regular brines do, and then some.
Baby-back ribs have a tight sheath of cartilage membrane, called a fell, covering the bone side of the rack. If it's left on, the fell constricts during cooking, misshapes the rack and, like cartilage does, leaves a chewy, shrunken remnant of itself that is anything but tender. It also prevents the brine from reaching the meat from the underside of the rack. Using a butter knife or metal skewer, work about 1 inch of the membrane loose from a corner of the rib rack -- enough to grasp it between your thumb and forefinger. Grasp this loosened tab and pull it from the rack -- it should come away in a single sheet. Use a paper towel to improve your grip on the membrane, if needed.
The brine standard is 5 percent salt content -- more than 5 percent and you risk introducing too much salt into the ribs. Too little, and you won't attain the benefits brining invests. Ideally, you should weigh the salt -- the weight of different brands varies by volume -- but if you use standard kosher salt and measure it by the cup you won't encounter any problems. Pour 1 gallon of room-temperature beer in a large saucepan or pot. Add 8 ounces of kosher salt, or about 1 cup, to the beer, and stir.
As with infused liquor, the alcohol in beer acts as a solvent in which the esters and flavonoids -- the compounds responsible for flavor and aroma -- become the solute, or the chemical extracted by the solvent. Beer's alcohol by volume varies, but an average domestic contains about 5 percent ABV -- not nearly as much as liquor, but enough to benefit the brine if you add aromatic ingredients. Save the dried spices for a dry rub and use fresh herbs and aromatics in a brine. A few crushed garlic cloves, a smashed knob of ginger, 5 or 6 fresh herb sprigs, a spoonful of crushed peppercorns and pinch of mustard seeds per gallon of brine goes a long way toward flavoring. Bruise the fresh herbs by pressing them with a spoon to release their oils; crush the garlic and any ginger you use with the broad side of a kitchen knife. Stir the aromatics into the brine.
Bring the brine to a boil to help the flavors coalesce. But before you do, add a tablespoon or two of sugar to offset the saltiness of the brine. Sugar isn't required, but it helps achieve balance. Once the brine reaches a boil, stir it once or twice and take it off the heat. After the brine reaches room temperature, transfer it to a nonreactive container -- stainless steel, glass or food-grade plastic -- and chill it in the refrigerator for about an hour. The container should be deep enough to submerge the ribs without overflowing the container.
After the brine chills to refrigerator temperature, submerge the ribs in it. You can stack the ribs flat on top of each other. If the ribs float from air trapped inside the fat -- which is rare -- set a plate on top of them to keep them under. Cover the container with its lid or a couple of tightly wrapped layers of plastic wrap, and return it to the refrigerator. When you're ready to cook, remove the ribs; pat them dry and let them reach room temperature.