What factors affect the color of meat ?
Myoglobin, a protein, is responsible for the majority of the red color. Myoglobin doesn’t circulate in the blood but is fixed in the tissue cells and is purplish in color. When it is mixed with oxygen, it becomes oxymyoglobin and produces a bright red color. The remaining color comes from the hemoglobin which occurs mainly in the circulating blood, but a small amount can be found in the tissues after slaughter.
The apparent color is affected by the amount of water in or on fresh meat. For example, proteins in meat with a low pH (<5.4) do not bind water very tightly. This "free water" in the tissues reflects light in many directions (scatters it) making the meat appear very light compared to higher pH meat in which water is more tightly bound. While these two pieces of meat may be the same color red, one may be much lighter (pale, soft exudative) than the other (dark, firm, dry), however, consumers often think one is more red than the other, and make purchase choices. The color of red meat changes over time as the pigments bind oxygen then ultimately become oxidized to brown or grey. Color also changes due to microbial growth, cooking and exposure to various ingredients (vinegar, salt). However, the conditions known as "pale, soft and exudative" (PSE) and "dark firm and dry" (DFD) are particular problems in the pork industry due to certain genetics and types of pre- and postmortem handling. Po
