As your blood travels through the rest of your body, the oxygen gets delivered to other tissues and taken off the hemoglobin. As the oxygen comes off the hemoglobin, it turns a dark red or purple color.
Then the hemoglobin gets back into your lungs, picks up more oxygen, and the process starts all over again. The same kind of thing happens in muscle with myoglobin. Check out this great explanation about the color of steaks from Mom at the Meat Counter. In meat, myoglobin starts out as a dark purple color. When it is exposed to oxygen either from hemoglobin in the blood or from the air , it turns red.
Enzymes in the meat use the oxygen. In order to use the oxygen, these enzymes take away some of the electrons from the iron in the myoglobin, which turns the myoglobin brown. In ground beef, things are a little bit different than in a steak or roast. Because so much of the meat is exposed to air when ground beef is made, the myoglobin gets saturated with oxygen. The enzymes that use the oxygen still work, turning the myoglobin brown. So the myoglobin and the meat stays brown.
When ground beef is packaged, the outside of the meat is exposed to air again, so it turns that pretty red color. The air can only penetrate so far through the meat, so the inside stays brown. When you get it home and break it open, the brown part of the meat should start to turn red again when it is exposed to the air! Neat, right? We can help! Shared on:. Well that may be in some cases but stores do turn meat I know when I was in school I worked in a grocery store in the meat dept before I went to classes.
Spoilage bacteria are generally not harmful but cause food to lose quality and develop a bad odor and taste 3. On the other hand, pathogenic bacteria are dangerous, as they can lead to food poisoning. Furthermore, spoilage makes it more likely for them to be present in your food. Ground beef may change color due to multiple factors, including temperature, light, microbial growth, and exposure to oxygen 4.
Fresh, raw ground beef should be red due to its levels of oxymyoglobin — a pigment formed when a protein called myoglobin reacts with oxygen 3.
The interior of raw ground meat may be greyish brown due to a lack of exposure to oxygen. Additionally, mold can spoil cooked ground beef, so you should toss your leftovers if you notice any fuzzy blue, grey, or green spots 5. Raw ground beef should be bright red on the outside and brownish on the inside. If its surface has turned thoroughly brown or gray or grown mold, it has gone bad and should be discarded. Fresh ground beef should have a relatively firm consistency that breaks apart when you squeeze it.
However, a sticky or slimy texture — either when cooked or raw — may indicate the presence of spoilage bacteria. You should toss it immediately To avoid spreading bacteria from one surface to another, wash your hands thoroughly after touching raw meat.
If your ground beef has a sticky or slimy texture when raw or cooked, it has most likely gone bad. This test is probably the easiest and fastest way to determine whether meat has spoiled. It applies to both raw and cooked ground beef. Though the scent of fresh ground beef is barely perceptible, rancid meat has a tangy, putrid odor. The scent changes due to the increased growth of spoilage bacteria, such as Lactobacillus spp.
Sell-by and expiration dates are additional guidelines for determining whether your ground beef is good 7. A sell-by date tells the retailer how long a product can be displayed for sale.
Ground beef can be refrigerated and safely eaten up to 2 days past this date 3 , 6. Food will have the best taste and quality before this date. Be sure to carefully read the product label when buying ground beef. Sell-by and expiration dates tell you the best time to eat ground beef. Look for ground beef with a bright red color. Ground beef can turn brown in the absence of oxygen. While this is not necessarily a sign of spoilage, extended exposure to air reduces the normal shelf life of the product.
Staff Login. Fridge time: 1 to 2 days Freezer time: 3 to 4 months. If using microwave or cold-water submersion methods of defrosting, following the general safe handling instructions. Note: Pregnant women, children, elderly and immuno-compromised individuals can be at an increased risk of developing foodborne illnesses that can have dire consequences. Additional care should be taken for safe handling.
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