Denaturation. Proteins and cells. Osmosis and diffusion. And what salt and water do to meat at the cell level.
We can make a roast chicken (or turkey) with more succulent meat and crispier skin by applying salt onto the surface before we cook the bird. It is the interplay of osmosis and diffusion and osmosis again that gives us such a delicious roast chicken.
The salt on the surface draws out water by osmosis. When some of the water evaporates during cooking, the highly concentrated salt solution will see salt diffusing (i.e. passing) into the chicken.
The more concentrated salt solution inside the chicken then draws water back in from the surface through osmosis (you can read the details in this 1-Minute NomNom “The wizard of os-mosis”)
At the cell level…
But what is going on in the protein structure at the cell level in the meat for all this to happen?
It has to do with what salt and water do to protein structure and cells. When the salt diffuses into the chicken, the proteins in the meat denature.
Proteins, on the other hand, are biological macromolecules and are polymers of amino acids. In meat, the proteins are myosin and actin (see far right).
When salt diffuses into the protein cells, the latter’s structure breaks down, i.e. protein denatures to accommodate the structure of the sodium chloride. Gaps open up as a result. Because there is now more salt in the cell, water is absorbed into the cells and fills these gaps. This makes the meat juicier.
There’s more (science… just a bit more)…
At the same time, when the protein denatures, some of it is dissolved by the salt, coagulating into a gel that traps and hangs onto the water even during cooking. Moreover, since the protein cells have denatured, the protein structure of the meat no longer holds up as well, and the meat is no longer as tough.
All these phenomena give us a juicier, softer and more tender piece of roast chicken (or turkey). Yums.
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photos: in order – depositphotos/ramirezom; aboikis; Dr.PAS; Leonid_Andronov; Paul_Cowan