If you use a thermometer fish is done at 145 degrees F. Meat. When you cut into thoroughly cooked ground meat, the color is no longer considered a reliable indicator of ground beef safety. Research indicates that a brown middles doesn't always signal doneness. Some ground meat may turn brown before it has reached a temperature at which bacteria are destroyed. Using a thermometer helps assure a safe product.
Hamburger patties are a common ground meat food.
Adding sauces or spices to hamburger patties may make them look brown before they're done. It's easier to tell if your patty is done if you brush or sprinkle sauces and spices onto the surface of the cooked burgers rather than add them to the raw burger. Below the temperature of 160 degrees F, the center of the roast will be pink or red, depending on the internal temperature. A beef roast cooked to 145 degrees F in the center can be considered safe since the exterior of the roast would have reached a temperature high enough to destroy bacteria, unless it is a rolled roast or one that has been mechanically tenderized. A consumer would not be able to determine if a roast that was pink in the center had reached the safe temperature of 145 degrees F without a food thermometer.