If you've ever cut into a burger to check if it's done, looked at the color, decided it was fine, and put it back on the grill — you've been using a system that the USDA has called an unreliable indicator of doneness for decades. Color feels like useful information. It looks like progress. But meat color is determined by chemistry, not by temperature, and the two don't always move together the way people assume. A brown burger can be dangerously undercooked. A pink one can be perfectly safe. The color is telling you something — just not what most people think it is.
What Actually Determines Meat Color
The color of cooked meat is primarily driven by a protein called myoglobin, which carries oxygen in muscle tissue and gives raw meat its red color. When meat is heated, myoglobin denatures and changes color — typically from red or pink toward grey or brown. But this process is affected by pH, fat content, the concentration of pigment in the meat, and the presence of other compounds. The USDA's own research found more than 25% of fresh ground beef patties turned brown before reaching the safe temperature of 160°F. That's a burger that looks done, tests as done by the only method most people use, and is still carrying live pathogens. Brown does not mean safe. It means the myoglobin changed color. Those are different things.
The Pink Burger That Was Actually Fine
The opposite problem is just as real. Meat can remain pink well above the temperatures needed to destroy harmful bacteria. The USDA has documented cases of ground beef remaining pink at internal temperatures of 160°F and above — fully safe by any food safety standard, but pink enough that most people would send it back or keep cooking. The cause is usually pH. Meat with a pH of 6.0 or higher denatures myoglobin more slowly, requiring higher temperatures and longer cooking times before the color shifts. Certain cuts, particularly those from older animals or with higher pigment concentrations, show the same behavior. Pink is not evidence of undercooked meat. It's evidence of myoglobin chemistry, which doesn't care what you think it's supposed to look like.
The Juice Test Isn't Reliable Either
The variation on the color check — piercing the meat and looking at the color of the juices — has the same problem. Clear juices are often cited as a sign that meat is fully cooked, and pink or red juices as a sign that it isn't. But juice color is also affected by myoglobin, pH, and the same variables that make meat color unreliable in the first place. The USDA is direct on this point: the color of the juices is not an accurate indicator of doneness. A food thermometer is the only way to know what's actually happening inside the meat. Everything else is interpretation of visual data that doesn't correlate reliably with temperature.
Why the Thermometer Is the Only Answer
A properly calibrated meat thermometer inserted into the thickest part of the cut gives you the one number that actually matters — the internal temperature, which tells you whether the heat has reached the level needed to destroy pathogens. Color gives you a visual cue that is sometimes correlated with doneness and sometimes actively misleading. The thermometer gives you the truth. The USDA's Meredith Carothers, a technical information specialist at FSIS, put it directly: color and texture are not reliable indicators of doneness, and a food thermometer is the only accurate way to ensure meat has reached a safe internal temperature. There's no ambiguity in that position, and the research behind it has been consistent for decades.
The Cuts Where This Matters Most
The color problem is most dangerous with ground meat, because grinding distributes any surface bacteria throughout the entire batch — and ground beef is the cut most likely to be judged by color. A burger that looks done can be harboring live E. coli in the center. Poultry is the other high-risk category, where the stakes of undercooking are high, and the color of the meat can vary significantly based on breed, age, and cooking method. Whole muscle beef is somewhat more forgiving because contamination is primarily a surface concern, but even there, a steak that looks grey and done on the outside can have a center that hasn't reached 145°F. The thermometer applies across the board.
Final Thoughts
Color is not a food safety tool. It's a visual cue that evolved as a rough proxy for doneness back when thermometers weren't widely available, and it was never reliable enough to be trusted as the primary check. The USDA has been saying this since at least 1998. A meat thermometer is inexpensive, takes seconds to use, and gives you information that color simply cannot. Use it every time, on every cut, and stop asking the meat to tell you something its color was never equipped to communicate.
The burger looked done. The thermometer tells you if it actually is.
Happy grilling,
The Harder Charcoal Team