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About Food Safety & Handling
What factors affect the color of meat and poultry?
Myoglobin, a protein, is responsible for the majority of the red color in meat and poultry. Myoglobin does not normally circulate in the blood but is fixed in the tissue cells. When bruising occurs during gathering, myoglobin circulates in the blood, and a small amount can be found in the meat after processing. This purplish color can leave small dark spots that resemble bruising. Exposure to light in the meat case can also affect color. (USDA)