Yosef Karo

“ But if they got blanched and then regained their normal appearance, it's kosher.
3 If these parts did not change but then it happens that they get blanched and their color changes - it's treif, since it had fallen into the fire before.
4 Changing tint yellow-green (yerakut) does not invalidate the liver of a domesticated bird whose species exist in the wild, for all the wild ones have a liver that's green like leek.
5 If it fell in a fire and it's unknown if its intestines got burned - it needs checking. If there's no one present who can check, it's forbidden. ”

“ Rema: And if the spleen is turned green at where it's against there, even if it's the smallest quantity, it's treif because it will ultimately have a hole (B"Y in the opinion of Rashba) . 2 The fact that a change in these parts invalidates it, is specifically when they remain changed after blanching (shalak) . ”