You bought some hamburger meat, and it had a fresh looking pink color to it. When you go to cook it a day or two later, you notice that it looks brown on the inside. Has it gone bad? Should you throw it away or cook it anyway? If you find yourself in this dilemma, this short guide can tell you all about the color of your hamburger and what it means when it goes bad.
So Many Colors
Meat contains a protein known as myoglobin. Myoglobin is ferrous iron-based and its natural color is purple. All meat, when it is first cut, begins as this purple color. As myoglobin is exposed to oxygen, the iron reacts to the oxygen and creates a ferrous iron-oxygen complex known as oxymyoglobin, which is a red color. When you buy your hamburger meat in the supermarket, it has been exposed to oxygen for quite some time and this is the color you’ll see.
Continued exposure to oxygen can change the color further. Oxymyoglobin can further react with oxygen to create metmyoglobin—turning the red color into a red-brown color. This occurs because the iron in the myoglobin loses an electron and becomes ferric iron. This process can lead to brown looking hamburger meat.
However, while all hamburger meat is exposed to oxygen when it is ground for the first time, once the ground beef is layered and placed in packaging, some of the meat is no longer exposed to oxygen. While the rest of the meat is turning to its reddish color, the interior may wind up looking grayish-brown.
Color Changes and Spoilage
The color changing explained above is natural and happens with all hamburger meat. It does not mean that the meat has spoiled and gone bad. However, not all color changes are safe. Some color change can mean that your meat has gone bad.
When hamburger meat spoils there will be a change in color, usually a fading or darkening. The difference is that this color change comes along with a bad odor or a change in texture. Hamburger meat that has spoiled will either smell bad or feel sticky or slimy. It is in these cases that your hamburger meat should be thrown out.
Cook within a Couple of Days
Hamburger should be OK as long as you use it within 1 to 2 days after purchase. Browning that occurs during these few days should be of the perfectly natural sort. After that time, you run the risk of spoilage. If you don’t plan on using your hamburger right away, put it in the freezer. It can be stored indefinitely that way—although you may lose quality if it’s not used within 3 or 4 months. Color changes to your hamburger can occur even while it’s in the freezer, but as long as it was still good when you put it in there, it won’t go bad.
Browning of the inside of your hamburger is natural and should not be a concern. If you aren’t quite sure if your meat has gone bad, be on the safe side and throw it out.