My grandmothers friend was wondering why Chicken bones some times turn black. She believed that this happened after the chicken was frozen... I thought it had something to do with blood clots or something of this nature. Plus I am not sure if the chicken already had the blackness to the bone, or if this only occurred after cooking. I could not find the answers on the internet. Please help!

Cooking a chicken or turkey too long makes the bones turn black.

I have found after making stock for chicken soup, that yes, the chicken bones have turned extremely dark. I am a cook, I know these things. You got an answer in my opinion and you said 'it may or may not be true'.

Years ago I heard that small amounts of arsenic were in the chicken feed which made chickens hungrier so that they ate more so they grew faster. That caused discolouration of the joint areas. I've also heard that very young chickens show this discolouration at the joint area - the bones and meat have a dark look - which is caused by the blood entering into the meat at the time of slaughter. Although cooking a long time will darken bones, this does not account for the discolouration in, for example, baked chicken pieces. This is worth more research, I think.

Kosher is slaughtered in a different way all together (that's why it is Kosher) so I don't think it is relevant.:)

Sorry, old thread, but I felt I needed to comment.:D

Commercial chickens are often slaughtered very young, before the bones have had time to completely calcify. This means that the bones are still very pourus, note that the ends of the bones, where the growth plates are, is the last to calcify. This causes the marrow to seep out of the bones during cooking and as it heats it turns dark. It's perfectly safe to consume.