At first, osmosis wicks out water from cells, forming those droplets of moisture that you see on freshly salted meat. Though it may appear that your meat is losing vital liquid, just wait a couple hours. That's when diffusion kicks in.
Diffusion is a slower process, in which salt evenly distributes itself in an environment to create balance. It takes a good chunk of time; salt permeates into meat tissue at a rate of just one millimeter — or about the width of a dime — per hour. After the first few hours, it travels even more slowly.
Samin Nosrat, author of "Salt, Fat, Acid, Heat," points out that as salt pushes into the turkey, it loosens coiled strands of proteins and causes the muscles to swell, pulling surface liquids back in. This prevents proteins from clumping up and squeezing out water molecules. As a result, the proteins get a better grip on moisture.
Because the meat retains more liquid in the oven, the turkey will come out juicy and tender. This extra moisture also gives nervous chefs a larger margin of error for overcooking.
When it comes to measuring salt for your dry brine, you'll need some simple math. The volume of salt crystals can vary depending on grain size; one cup of smaller-grained table salt could hold more salt crystals than a cup of larger-grained sea salt. Your best bet is to go by weight.
"As a chef, I would never use volumetric measurements because they're too unreliable," said food chemist Chris Young, founder of ChefSteps and coauthor of Modernist Cuisine. You can measure the same salt in the same measuring cup several times, and you'll find its weight differs by about 5 or 10 percent each time based on how you pack the cup, he said.
Instead, take a kitchen scale and calculate 1.5 percent of your turkey's weight in salt. Letting your dry-brined turkey mellow in the fridge for the next 24 to 48 hours will transform a tough bird into a scrumptious, tender delight.
If your kitchen doesn't have a weighing device, here's a nifty trick: Young recommends heavily coating your turkey in salt, letting it sit for an hour and then rinsing off the excess before adding seasonings and refrigerating. The turkey won't be too salty, because it won't be exposed to the salt long enough to cure the meat.
The Best Roast
Say you want more than juiciness. You're looking for crackling skin, bursting with rich, savory flavors.
Try amping up the Maillard reaction.
Whenever you happily munch on the deep brown crust of a hunk of bread or delight in a juicy steak, you're indulging in a symphony of flavors created by the Maillard reaction, otherwise known as "nonenzymatic browning."
During the Maillard reaction, amino acids — the building blocks of proteins — and sugars in the meat break down with time and temperature. They recombine into thousands of new flavor compounds in what chef and author J. Kenji López-Alt calls a "cascade of chemical reactions."
These new compounds are responsible for the enticing aromas and fragrant flavors that emerge after roasting, baking, frying and searing foods. And this reaction really packs a punch.
"The amazing thing is some of these compounds are formed in infinitesimal amounts, and yet we can still smell it," Young said. "You put a single droplet of a particular roast flavor of meat into an Olympic sized swimming pool, the water would taste beefy."
Scientists still struggle to understand the complex mechanisms behind the Maillard reaction. They know the reaction creates compounds like nutty and sweet chemicals called furans and savory chemicals called thiophenes, but they have been unable to nail down how long it takes or which temperature is ideal.
The reaction kicks into gear at temperatures above 220 degrees Fahrenheit, the point at which water starts boiling off, leaving behind higher concentrations of proteins and sugars. However, if temperatures exceed 340 degrees for long periods of time, food can undergo pyrolysis — a type of heat-induced decomposition.That creates bitter flavors even before the exterior looks burned.
We roast Thanksgiving turkeys at a high temperature over a relatively quick time span to maximize the Maillard reaction. We don't boil our Thanksgiving turkeys, for example, because we want water to evaporate, leaving a high concentration of sugars and proteins to react. A method like boiling also means that the turkey's skin wouldn't dehydrate in the oven, and it would never get crispy.
At some point during the cooking process, acidic byproducts interfere with the Maillard reaction, causing it to slow down. Luckily, food chemists like Young and López-Alt have found a nifty trick to overcome this hurdle: baking soda. Baking soda works by increasing the pH level of a batter, mixture or surface to neutralize the acidic by-products.
As food chemist Matt Hartings explained, every amino acid has a side chain made of nitrogen attached to hydrogen ions. As you increase the pH level, one hydrogen ion detaches from the side chain, removing the positive charge. The uncharged nitrogens are now more likely to go through the Maillard reaction, speeding up reaction rates.
To bring this reaction to your Thanksgiving masterpiece, dissolve a small amount of baking soda into water and lightly brush it onto the surface of your turkey just before putting it into the oven.. Young recommends using about 1 percent of your turkey's weight in baking soda.. You can also add some baking powder to your dry brine — although it's not alkaline enough to significantly raise the pH like baking soda will, its leavening properties will form tiny bubbles in the skin, which will also crisp up nicely in the oven.
If you're still skeptical about using dry brines with baking soda (or baking powder), you can experiment with caramelizing onions. Simply divide the cooking onions into two separate piles and add a pinch of salt and baking soda to one half. After a few minutes, the onions with salt and soda should be sweeter and browner than the other half.