food&fish wrote:So to brine a chicken how much salt in say 4 liters water also do you put anything else in the water
Normally I wouldn't bother with such a detailed discussion, but since the topic header is "the science of brining", I thought I would make a more detailed post
To get an idea of the magnitudes of salinity involved, here are a few numbers for you.
- Normal concentration of salt in blood = 0.9% (i.e. 9gm NaCl dissolved in 1000mL water)
- Concentration of salt in food which tastes "excessively salty" = 2.5%
- Concentration of salt in seawater = 3.5%
- Target salinity for brined chicken = 1.5%.
Suppose you have a 2kg chicken and 4L of water. Let us also assume that the chicken starts of with uniform salinity of 0.9% throughout, and that it is possible to achieve uniform salinity when exposed to another solution (in practice, the salinity never equilibrates - I am only making an assumption for the purpose of this calculation). If you leave the chicken in there for a day, and assume everything equilibrates, the water and chicken will have a final salinity of 0.3%
If you salt the water so that the concentration of the brine is 8% and leave it to equilibrate, the final salinity will be 5.6% (80*4 + 9*2) / 6000 - way too salty.
If you use an 8% brine but use only 2L of water, the final salinity will be 4.45% (80*2 + 9*2) / 4000.
It should be clear that there are 4 factors that affect the final salinity of the chicken:
1. Concentration of salt in the brine,
2. Amount of time you leave the chicken in the brine, and
3. The volume of brine that you have used.
4. The rate at which salt diffuses through the chicken (this in turn is dependent on other variables, e.g. thickness of meat, whether the chicken has been cut to pieces, etc).
The third point is often something which is missed when people discuss brine recipes. This is why a brine recipe that works for me may not work for you. You choose the volume of brine you need to cover your chicken, and in your pot - and my size of chicken and shape of my pot is definitely different to yours.
The fourth point illustrates another important but frequently forgotten factor when it comes to brining. The shape and cut of the chicken matters. 2kg of sliced breast meat will brine differently to 2kg whole chicken, simply because the sliced breast meat will brine very quicly and will
equilibrate, whereas a whole chicken will brine slowly and never equilibrate. I do not know the rate at which brine penetrates whole chicken. If I did, I could do a calculation and give you a formula to calculate exactly how much brine you need and how long you need to brine it for to achieve the desired final salinity. This is part of the uncertainty of brining.
As for the first two points (concentration of salt, and amount of time) - you can think of this in a similar way to cooking. Just as high heat means short cooking time - at the risk of overcooking the surface and undercooking the interior - high salt means shorter brining time at the risk of uneven brining. There is no easy way to test salinity unfortunately - if you use a salinity meter you have to somehow remove a piece of chicken and then measure it.
Having said all that, you will find a variety of brine recipes on the 'net. Heston recommends a 6% brine for 8-10 hours. I find that this brine results in juicy, tender, but underseasoned chicken. I personally prefer an 8% brine for 8 hours. I tend to use 4L of water for 2kg chicken. Again, take note of the various factors that might affect the outcome of my brine recipe to yours. What is important is that you develop your own brine recipe and stick to it.