Strictly speaking, brining means soaking something in a brine solution, that is, a mixture of salt and liquid, usually water, often with the addition of sugar and spices. Pickles are made by brining, often substituting vinegar for the water. Brining is an ancient method of food preservation that has recently made a culinary come-back as a way to improve the texture and flavour of lean meats like pork as well as chicken, turkey, and shrimp. I'm going to focus on brining meats, drawing information on the hows and whys from the champions of the technique, Cook's Illustrated magazine.
To prepare enough brine for 1 pound/.5 kg of food, combine:
- 1 quart/4 cups/1 litre of cold water
- 1/2 cup/120 ml kosher salt or 1/4 cup/60 ml table salt (Cook's Illustrated recommends kosher salt because it's more pure and has an airier structure, making it dissolve more quickly)
- 2 tablespoons/30 ml to 1/2 cup/120 ml sugar (use the lesser amount of sugar if you're broiling or high-heat grilling, because you don't want the skin to burn)
- (optional) for extra flavour, add crushed peppercorns, bay leaves, coriander seeds, and the like
Cook's Illustrated recommends that you combine all this in a large heavy-duty ziplock plastic bag, which does make it easy to submerge your food in the brine, remove as much air from the bag as possible, zip it up, and put it in the fridge for 30 minutes to 8 hours. If you don't have bags and have to do this in a bowl or pot, it may help to weigh the food down so it's completely covered in brine.
What's happening as the food sits in the brine is that it wants to reach a state of equilibrium, so it draws salt, sugar, and water from the surrounding medium into the food substance. Then, when you cook the food, it retains more moisture and is better seasoned.
Note that chicken and turkey skin can get kind of waterlogged from brining, so it helps to air dry the poultry on a rack in the fridge for several hours before cooking.
Why wouldn't brining work as well for beef or lamb? Because they are generally served more rare, so they are cooked to a lower internal temperature than chicken or pork; if you like your beef well-done, you might try it. In addition, beef and lamb, as well as poultry like duck or goose, contain more fat than pork or chicken, which makes them more flavourful and moister. Cook's Illustrated also claims that brining firms up shrimp, but I'm just the bearer of news here because I haven't tried it. I will say, though, that brining chicken, turkey, and pork does result in a much more juicy, flavourful end product. Try it.