Tossing beef that appears to have turned brown

If you've ever seen ground beef that has become brown, you might have assumed that microbial growth is to blame. A portion of ground beef that changes from pink to brown, however, doesn't necessarily indicate that the meat is rotten. The USDA states that fresh beef first displays a reddish hue when chopped. Oxymyoglobin, a flesh pigment that reacts when beef is exposed to oxygen, causes the meat to turn redder and eventually take on the distinctive pink hue you may see in your grocery meat section. Meat pieces will remain brown or even grey if they are not exposed to oxygen.

According to the USDA, ground beef that is still brown should be safe to consume. Having said that, meat left outside in an atmosphere with lots of oxygen fosters the growth of bacteria. A chunk of meat will become brown as bacteria spread throughout it and continue to proliferate. However, the USDA advises that cooked raw brown ground beef should be safe to consume provided there are no other indications of spoiling, such as an unpleasant odor.