Meu conhecimento sobre o fenômeno em si é limitado, mas eu o vi mencionado em "Modernist Cuisine" (Nathan Myhrvold, p. 147)
Many recipes for foie gras, liver, sweetbreads, and other offal include a soaking step before cooking. For kidneys, this step serves a very simple purpose: to remove any trace of the animal's bodily fluids. Recipes often call for soaking foie gras, liver, and sweetbreads in milk. It is often said that milk improves the taste, purges blood, lightens the color, or affects some other property of the meat. We were skeptical, so we tried several experiments. With a mild-flavored organ meat like foie gras, we could taste a difference, but, frankly, in our tests, we prefer the taste of water-soaked to milk-soaked foie gras. With stronger-flavored organ meats, there is even less of a difference than with foie gras. So our suggestion is to simply soak the meat in water.
Então, você tem isso.