Red meat is named such due to the higher amounts of myoglobins present in the animal’s blood as compared to poultry or fish. Red meat includes pork, lamb and veal, all of which can react to the presence of oxygen. When red meat is vacuum packed, it will turn a deep burgundy or purple due to the lack of oxygen. Once the package is opened and exposed to air, the myoglobins receive oxygen and the meat turns a bright red. Clear plastic wrap allows some oxygen to pass through, so the meat remains an attractive red color.

After your package of raw meat has been stored in the refrigerator for five days or more, it may fade, darken or turn an unappetizing gray. This indicates a chemical change has occurred in the protein of the meat. Examine this meat carefully before cooking. After extended storage, the gray-brown color is a sign of spoilage if the meat is also sticky to the touch, smells bad and develops a clear goo on the meat’s surface. Do not taste or cook this meat; instead, throw it away.

Raw meat stored in the coldest parts of a refrigerator between 39 and 40 degrees Fahrenheit stays fresh for three to five days after purchase. Ground meat only keeps for one to two days. To extend its storage life, especially if you are going out of town, freeze your meat. While it’s safe to just pop your meat in the freezer in its clear plastic wrap, long-term storage requires better wrapping. Using aluminum foil, freezer paper or bags marked as “freezer safe” will prevent gray patches -- known as freezer burn -- from drying out your meat. If your meat does turn gray from freezer burn, it is still safe to eat; just trim away the gray.

While frozen meat can be cooked without thawing, it will take 50 percent longer to reach safe internal temperature. To safely thaw frozen meat, remove it from the freezer and store it in the refrigerator. Ground meat will be ready to cook in one or two days; whole, bone-in roasts may take up to five days to defrost. A roast thawed in the refrigerator can keep an additional three to five days before being cooked. For faster thawing, submerge raw meat in cold water, using a leak-proof bag, changing the water every 30 minutes. Microwaves can also thaw frozen meat, but the meat may become partially cooked with this method, so it must be used right away. Partially cooked meat cannot be put back in the freezer for storage because bacteria may be present.