Advertising touts pork as "the other white meat" because its color goes from pink to a light opaque color when cooked. But according to the USDA, pork is a red meat. Oxygen is delivered to muscle within swine by red blood cells, and this oxygen is held within the muscle by a protein called myoglobin. The amount of myoglobin present in an animal's muscle is what determines whether its meat is classified as red or white. Pork has more myglobin than poultry, but less than beef.
Myoglobin and Meat Color
A variety of factors affect to what degree meat changes color when cooked. Caramelization, or the browning of natural sugars present in the meat, impacts the surface color. When high heat denatures myoglobin during the cooking process, meat with little myoglobin, such as pork, changes from pink to tan or white.