Sous Vide At Home -
The Science Behind Brining
With Turkey Day quickly approaching, there has been a lot of talk on the web about whether or not you should brine your bird. Although there are good arguments from both camps, I think it is first important that the science of brining is understood before making any decisions.
A traditional brine is a water based liquid that contains between 3-6% salt by weight. Along with salt, a brine will contain aromatic herbs, spices and sometimes vegetables (usually mirepoix, garlic, etc).
So Why Would You Brine Meat?
Brining has two distinct effects on muscle tissue.
First, the high salinity of the brine “disrupts the structure of the muscle filaments” (On Food and Cooking, Pg 155). At about 3% salinity, the brine will partially dissolve “the protein structure” which supports the muscle filaments that contract when cooked. The more these muscles filaments are allowed to contract, the tougher your meat will be.
At about 5.5% salinity, the muscle filaments themselves are partially dissolved. Since their contracting ability is hindered by the salt, the muscle filaments contract less, effectively making your meat more tender.
Second, they way in which salt interacts with protein, allows the protein to retain more moisture, which is absorbed from the liquid of the brine itself. According to Harold McGee’s on Food and Cooking:
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 counterbalanced by the brine absorbed, so the moisture loss is effectively cut in half. (PG 156)
This is what allows brined meat to stay more moist, compared to its unbrined counterpart.
The reason why a lot of people prefer to brine their turkey for the big day is because turkey breasts are finished cooking at around 145 degrees F, and start to dry out at around 155 F. The legs on the other hand need to be cooked to about 165 degrees F, because they have a much higher amount of connective tissue (in the form of collagen), and collagen doesn’t begin to break down until about 160 degrees F.
So by the time the turkey legs are done, the breasts are overcooked and dried out.
The problem with brining a turkey is the drippings contain much more water, and are too salty to make a proper pan gravy. Harrold McGee actually doesn’t brine his Thanksgiving Bird, and he explains why in his New York Times Article “Miracle Cure or Just Salt Water?”
Also, check out this Stella Forum Thread on Brining.