Frequently Asked Questions : Beef

I purchased ground beef and noticed that outside surface was reddish brown but inside meat was red. Is this safe to eat or is it going bad?
This colour change does not mean the meat has gone bad. Optimum surface colour of fresh meat is highly unstable and short-lived. When meat is fresh and protected from contact with air, it has the purple-red colour that comes from the pigment myoglobin. When exposed to air, myoglobin forms the pigment, oxymyoglobin, which gives meat the cherry red colour. The use of plastic wrap that allows oxygen to pass through it helps ensure that the cut meats will retain this bright red colour. However, exposure to store lighting as well as the continued contact of myoglobin and oxymyoglobin with oxygen leads to the formation metmyglobin, a pigment that turns meat brownish-red.