According to the United States Department of Agriculture, a change in a steak's color does not mean that the steak is spoiled. To determine if steak is safe to eat, its smell, appearance and texture should be examined. A foul odor, tacky feel or a slimy appearance are all signs that the meat has spoiled.
The color of meat is affected by the age, sex, species, diet and activity level of the animal. Animals that were active or older tend to have meat that is darker in shade.
Reactions between the meat's myoglobin and oxygen can cause the color of meat to change. These reactions are harmless and do not cause the meat to go bad.