2,556. Green to Red, Red to Green

Hilchos Shechita 7:20

If a bird falls into a fire and its heart, liver or craw turns green, or if its digestive organs turn red, the bird is a treifa; this is so even if only the smallest portion changes color. This is because whenever fire turns green organs red or red organs green, it’s as if the organ were removed, with the result that the animal’s a treifa, provided that the organ remains this color after slight cooking and being rubbed.

Hilchos Shechita 7:21

If the liver of a bird looks like its digestive organs, or if one of the other digestive organs changes and stays that way after slight cooking and rubbing as has been explained, we assume that the bird fell into a fire and the digestive organs got burned, with the result that it’s a treifa. Not only that, if there’s no apparent change in a bird’s digestive organs, but they change color when cooked slightly so that green organs turn red or red organs turn green, we assume that the bird fell into a fire and its digestive organs got burned, rendering it a treifa. Similarly, if the esophagus changes so that the outer skin is white and the inner is red, it's as if it’s missing, and the animal or bird is a treifa.