Myth: If Meat Turns Brown, That Means It Is Spoiled
Red meat products are somewhat like sliced apples. Their color can change rapidly – even though the product is still safe and wholesome. In fact, retail stores often discount red meat products that have changed color but are still safe and wholesome – and well within their shelf life. These color changes in foods like apples and meat are the result of chemical changes caused by oxygen exposure. 1
The untouched surface color of fresh meat such as cherry-red for beef is highly unstable and short-lived. When meat is fresh and protected from contact with air (such as in vacuum packages), it has the purple-red color that comes from myoglobin, one of the two key pigments responsible for the color of meat. When exposed to air, myoglobin forms the pigment, oxymyoglobin, which gives meat a pleasant cherry-red color. The use of a plastic wrap that allows oxygen to pass through it helps ensure that the cut meats will retain this bright red color. However, exposure to store lighting as well as the continued contact of myoglobin and oxymyoglobin with oxygen leads to the formation of metmyoglobin, a pigment that turns meat brownish-red.
Color is also not an appropriate indicator of whether meat is cooked. The only clear way to tell if meat is cooked thoroughly is to use a meat thermometer to ensure it has reached the recommended internal temperature for that meat.
Beyond color change, there are ways you can tell if your meat is spoiled. Spoilage is a process that occurs over time and is the result of the growth of spoilage bacteria. There is no one point in time where a product is fresh and wholesome and then suddenly becomes spoiled. Changes in color can be an indicator that the process is beginning, but color change alone does not mean the product is spoiled. The most potent indicator of spoilage is an off odor. A spoiled product also can be sticky or tacky to the touch, or it may be slimy. If meat has developed these characteristics, it should be discarded. A use-by date on a package can also be a good guideline.
Some meat may also show an iridescent sheen. This is because meat contains iron, fat, and other compounds. When light shines on a slice of meat, it splits into colors like a rainbow. There are various pigments in meat compounds that can give it an iridescent or greenish cast when exposed to heat and processing. Wrapping the meat in airtight packages and storing it away from light will help prevent this situation. Iridescence does not signal decreased quality or safety.
USDA generally recommends the following:
- Raw ground meats, all poultry, seafood, and variety meats: can be refrigerated 1 to 2 days.
- Raw roasts, steaks, and chops (beef, veal, lamb, and pork) can be refrigerated for 3 to 5 days.
- Cooked meat, poultry, and seafood can be stored in the refrigerator 3 to 4 days.