What It Actually Means When Your Roast Beef Turns Gray

Piled high on Dutch crunch bread with provolone and Dijon mustard, or folded into a French baguette with Swiss, grilled onions, and toasted, roast beef has different cuts that make great sandwiches. Whether you buy roast beef at your local deli counter or roast it at home in your oven, you may notice that after several days in the fridge, your pink roast beef looks gray. Why? 

Considering that the CDC reports that approximately 48 million Americans get sick from food poisoning annually, it's natural to show concern when your roast beef starts changing colors. According to the USDA, freshly butchered beef is a dark purple-red, but when exposed to air, the pigments in meat react with oxygen and transform to a bright red color — what you typically see on ground beef packets in the grocery store. Sometimes you'll get beef that's gray in the center, but more often than not, it's simply an indication that oxygen was unable to reach the inside of the meat.

All meats contain lipids, or fats, that are highly susceptible to oxidation — caused by exposure to air and light– which leads to degradation of the food. Unlike the rainbow or iridescent spots seen on deli meat, when roast beef starts to go gray, it can be a sign of spoilage, but there are other ways to tell if your roast beef has gone bad. In addition to visual cues, spoilage can also be detected through odor and texture. If your gray roast beef smells sour and feels slimy or sticky, it's probably past time to throw it out.

As with any fresh food product, storage is important for safety. Be sure to keep roast beef in the coldest part of your refrigerator, at least 40 F. Freshly sliced roast beef from the deli should be eaten within five days, and pre-packaged items should be consumed within five days of opening. Although gray meat doesn't always indicate spoilage, you should always play it safe and be sure to employ all of your senses before tossing it out.