The form of myoglobin and other factors contribute to cooked meat color and make color a poor indicator of if meat is safe to eat.
Have you ever eaten a hamburger that is brown in color and actually undercooked? What about one that is still pinkish in color and safe to eat? If you are scratching your head thinking this is not possible, purchase and use a meat thermometer and see what happens. Michigan State University Extension indicates that using a meat thermometer is the only safe way to determine doneness of meat. Color is not an indicator of doneness, especially in ground meats. Ground meat needs to be cooked to 160 degrees Fahrenheit, whole muscle meats to at least 145 F, and poultry to 165 F.
Myoglobinbreaks down during cooking and causes meat to be brownish in color when cooked to well done (170+ F). Meat at lower degrees of doneness such as rare (140 F) and medium rare (145 F) has not fully denatured and still provides some red or pinkish red color to the cooked meat. For the most part, this holds true for whole muscle fresh meat purchased at retail, however this is not always the case. The presence of oxygen and the state that the iron attached to the myoglobin protein can determine what cooked color actually appears.
Premature browning is what happens when the inside of a ground beef patty is completely brown but not cooked to a high degree of doneness (around 130-135 F). This can pose a significant food safety problem, especially for consumers who rely on color as an indicator of doneness in ground beef. Ground beef that has a higher amount of oxidized myoglobin in the metmyoglobin form is more apt to result in premature browning. Other factors that can contribute to premature browning include exposure to oxygen during packaging, pH, freeze-thaw dynamics of patties, the length and temperature meat was stored at, type of muscles that were used in grinding and the addition of salt to the meat. Since metmyoglobin is brown in color, it is not surprising that hamburger containing metmyoglobin will be brown in patties regardless of the endpoint temperature. The important part to remember is that cooked ground beef must be cooked to an internal temperature of 160 F for one second, regardless of its internal color.
Persistent pink is when portions of fully cooked meat have red or pink appearance to them. Persistent pinking is found on the inside of a ground beef patty and when not all of the myoglobin breaks down during cooking. This occurs more when the iron on the myoglobin protein is in the reduced state and is purplish (deoxymyoglobin) or red (oxymyoglobin) in color, if the meat has high myoglobin content (from cows or bulls), and if muscle pH is higher. Increasing the endpoint temperature of this kind of meat may decrease the pinkness, but it may never turn completely brown. Persistent pink also can occur in the first few millimeters of the surface of a meat product. This is most common in meat grilled on charcoal or gas and shows up as a pink ring. The gas nitrogen dioxide may be present during the cooking as the fuel combusts. This creates a pigment from myoglobin called nitrosylhemochrome. The pink ring that forms near the surface of the cooked meat often fades or disappears after it is exposed to air or light. The bottom line regarding persistent pinking in cooked meat is that it is safe to consume providing the endpoint temperature is confirmed with a thermometer.
The majority of the original research conducted on premature browning and persistent pinking was conducted at Kansas State University.
Other articles in this series
The color of meat depends on myoglobin: Part 1
Cured meat color: Part 3
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FAQs
In cooked meat products, dull-brown interiors are considered the hallmark of a well-done product, whereas a pinkish interior color indicates meat cooked to a lower degree of doneness, which can be undercooked and unsafe (King & Whyte, 2006).
What is the color code for cooked meat? ›
Yellow chopping boards should be used for cooked meat. Do not use the same cutting board for cooked and raw meat as this can lead to cross-contamination of food. The yellow chopping board can be used for cutting cooked chicken, for instance.
Can you still eat a meat with greenish color? ›
Spoiled meat will change in colour, smell very pungent and wrong, and will be slimy to the touch. If you end up cooking that meat, it will also not taste very good. If your meat has turned a tinted white-blue, green, gray, purple-brown, or any other unusual colour, it doesn't belong on your barbecue or your plate.
Why does meat turn color when cooked? ›
Myoglobin breaks down during cooking and causes meat to be brownish in color when cooked to well done (170+ F). Meat at lower degrees of doneness such as rare (140 F) and medium rare (145 F) has not fully denatured and still provides some red or pinkish red color to the cooked meat.
Can cooked meat still be pink? ›
To be sure all harmful bacteria are destroyed, cook all ground beef products to an internal temperature of 160 °F throughout. Ground beef can be pink inside after it is safely cooked. The pink color can be due to a reaction between the oven heat and myoglobin, which causes a red or pink color.
Why is my cooked meat purple? ›
There are two types of myoglobin: oxymyoglobin and deoxymyoglobin. Oxymyoglobin is the form of myoglobin that is oxygenated and gives fresh Beef its red colour. Deoxymyoglobin is the form of myoglobin that is deoxygenated and gives aged Beef its purple colour.
What color is medium cooked meat? ›
Medium (140°-150°F)
A steak cooked “medium” will be mostly pink. A small ring of grey may form on the outside and a strip of red will remain in the center. For steaks with more marbling, this will be the temperature where the fat begins to liquefy and add flavor.
What is the color change in cooked beef? ›
The color of cooked ground beef can be quite variable. At 160 degrees F, a safely cooked patty may look brown, pink or some variation of brown or pink. When a patty is cooked to 160 degrees F throughout, it can be safe and juicy, regardless of color.
What color of meat is safe to eat? ›
Look: Red meat should be bright red — that's when it's at its freshest. If it turns purple or brown-ish, it is probably still safe to eat, but it has been exposed to some oxygen. As raw chicken spoils, it turns from pink to a greyish colour.
Why is my cooked meat green? ›
Sliced cooked beef or lunchmeat can have an iridescent color. Meat contains iron, fat, and many other compounds. When light hits a slice of meat, it splits into colors like a rainbow. There are also various pigments in meat compounds which can give it an iridescent or greenish cast when exposed to heat and processing.
The green discoloration usually shows up after an anaerobically stored product is exposed to air and thus the spoilage may not be apparent until the package is opened by the consumer. Lactobacillus viridescens is the most common greening bacteria but Streptococcus spp. and Leuconostoc spp.
Can you eat meat that looks GREY? ›
If only the interior is gray, you can bet that oxygen hasn't touched it to turn it red. This means ground beef with a gray interior is safe to eat. On the other hand, meat that looks gray or brown all over (on the inside as well as the top layer) has likely begun to spoil and is not safe to eat.
Is meat still good if it changes color? ›
This darkening is due to oxidation, the chemical changes in myoglobin due to the oxygen content. This is a normal change during refrigerator storage. Beef that has turned brown during extended storage may be spoiled, have an off-odor, and be tacky to the touch and should not be used.
How to tell if meat has gone bad? ›
Obvious signs of spoilage, like mold, are clear indicators that you'll be tossing that cut and buying a new one. Other tell-tale signs of spoilage include meat that looks slimy, shiny, crusty, and/or off color.
How can you tell if meat is cooked by color? ›
A consumer preparing hamburger patties and using the brown color as an indicator of doneness is taking a chance that pathogenic microorganisms may survive. A hamburger cooked to 160 °F (71.1 °C), regardless of color, is safe. The only way to be sure food is safe is to use a food thermometer.
How can you tell if meat is fully cooked? ›
When you pierce the thickest part of the meat with a fork or skewer, the juices should run clear. For a whole chicken or other bird, the thickest part is the leg between the drumstick and the breast. Cut the meat open with a clean knife to check it is piping hot all the way through – it should be steaming.
Is dark meat still pink when cooked? ›
The USDA says that as long as all parts of the chicken have reached a minimum internal temperature of 165°, it is safe to eat. Color does not indicate doneness. The USDA further explains that even fully cooked poultry can sometimes show a pinkish tinge in the meat and juices.
Why is cooked meat gray? ›
Metmyoglobin, a process that happens when a protein in muscle tissue called myoglobin reacts with oxygen, causes a loss of color that causes your steak to turn gray, but don't worry, it is entirely safe to eat as long as it is not slimy or has an unpleasant odor.
Why is cooked meat iridescent? ›
Meat contains iron, fat, and other compounds. The commonly accepted mechanism for iridescence involves optical light diffraction resulting from muscle's striated structure and fibrous nature. When light hits a slice of meat, it splits into colours like a rainbow.
