Cooked or not cooked Saint-Jacques?
It seems improbable to you and yet, who has never observed the blanching of the Saint-Jacques pulpit after having seasoned it with lemon? Although it looks like a cooked scallop, you haven’t raised the temperature. What happens then?
Lemon contains a well-known acid: citric acid, which gives it a pungent taste on the tongue.
This citric acid attacks the proteins that make up the Saint-Jacques flesh. How? Not by breaking them into small pieces, but by unwinding them or destroying their 3D shape. In other words, proteins, which are gigantic molecules, collapse and shrivel on themselves.
Denaturation of cold proteins.
This is called protein denaturation. This denaturation involves a modification of the physical, biological and chemical properties of the latter. This explains the change in color.
You will make exactly the same observation with fish or meat when you let them macerate in a marinade made up of lemon or vinegar. Except that instead of “cooking” in a few minutes, they will need a few hours of cold dip.