Most of us have heard of brining meats, and some of us have even cooked using the process, but how does brining actually produce a moist end product? Before I get into some of my findings, I want to start out by stating that even today, there isn't a scientific reason that everyone agrees on. From what I can tell though, the main discrepancies lie in the terminology used, rather than the overall picture (as you'll see shortly). Despite these differences in explanations, brining does work and no one is denying that. The following is my take on the process after reviewing several trusted sources.
|Although I altered several units and added a new column, credit goes towards Cook's Illustrated's The Science of Good Cooking for the general layout and quantities.|
- The salt must be fully dissolved in the water before you add your chicken, turkey, or pork. Contrary to countless recipes, this can done by simply stirring the salt mixture for a minute or two, rather than heating up the water, dissolving the salt, and completely cooling the mixture back down.
- Your submerged protein must be fully immersed. This can be accomplished using a ziplock bag for smaller cuts of meat, or else putting some sort of weight on the top of a whole bird if using a large container.
- To keep the process safe, the brine must stay at 40° F or slightly cooler. The refrigerator is an ideal place to achieve this temperature, but if your container is too large, add ice packs to the brine to bring the water down to temperature. The main point to make here is that letting your pork or poultry sit in the brine at room temperature is a no-no!
- When done brining, make sure to pat your meat dry using paper towels. This will allow for any seasonings to stick and will help achieve a crispy sear.
When a cut of meat is submerged in a brine, you have a protein that naturally contains a certain amount of water, and a solution that is almost entirely water. Since molecules will naturally move from areas of higher concentration to areas of lower concentration until equilibrium is met, the cut of meat will naturally absorb water from the brine. This general idea is referred to as diffusion, not the more commonly used term: osmosis.
Unlike diffusion, osmosis deals with "the movement of water from an area of higher concentration to that of a lower concentration, through a semi-permeable membrane." If osmosis applied towards brining, this would mean that the dissolved salt in the brine would not be able to pass through the semi-permeable membrane. To counteract this unbalance, water would move from the protein to the brine until the water content between the two reached equilibrium. As several sources have pointed out, osmosis does not occur during brining for two reasons. First, it is clear that the cut of meat gains a saltiness after brining, hinting that water from the brine flows into the cut of meat (and not the opposite). Second, if osmosis were actually occurring, water would flow out of the cut of meat, actually drying it out. We know this is not the case since protein is visually larger (and heavier) after brining due to the gain in water.
So far we've seen that water plays a huge role in brining, but where does the addition of salt come into play? As some of us may remember from chemistry class, the chemical makeup of salt is sodium (+) and chloride (-). As these ions break up in a solution of salt dissolved in water, they seek out areas of lower concentrations and aid in the 'juiciness factor' through several ways. Chloride ions enter muscle fibers and tend to group alongside the cylindrical walls (rather than clumping together) due to their like-forces. Because of these like-forces, a gap is widened within the muscle fibers and allow for more water to enter. Imagine being able to line the insides of a tube balloon with tiny magnetic disks. If they're all positioned so that the positive poles are all facing the inside (towards each other), the balloon will expand. This is essentially what is happening with chloride ions.
In addition to increasing the volume within muscle fibers, sodium and chloride ions actually cause protein molecules to readjust their positions to accommodate for the new opposing charges. This physical readjustment of molecules actually "compromises the structural integrity of the meat." Thus, salt helps make your lean meat more tender in addition to retaining more water.
Pretty interesting stuff, eh? I still have my own questions (as do others) regarding the science behind brining, but it's nice to have a decent grasp behind why it works.
Sources used in this article include stella culinary (who largely cited Modernist Cuisine: The Art and Science and Cooking in their findings), The Science of Good Cooking, and The New Best Recipe.