During the cooking process, myoglobin is denatured.
All of the pigment is not affected at the same time or
to the same extent and this is why you get reddish
color at different end point temperatures when
cooking. The cooked pigment is denatured
metmyoglobin. It is brown and is easily recognized in
cooked meat products. Certain meat conditions can
result in protection of the myoglobin.
The ultimate pH of the muscle is one of these
conditions. The ultimate pH of meat or meat
products will affect how the meat color changes
during cooking. If the meat has a high pH, it will
have to be cooked to higher end-point temperatures
to get the same visual degree of doneness as one
with normal pH. Frequently, complaints of this hard
to cook defect are associated with a high pH of the
meat or meat product. This meat appears raw in
color, dark red to purple, long after appropriate
cooking temperatures have been reached.