Like hamburgers made from beef, undercooked lamb burgers run the risk of contamination with disease-causing bacteria. The lamb's color can indicate the degree of doneness, but it's sometimes misleading. Exposure to smoke, light and freezing temperatures all affect the color of the lamb, whether it's rare or well done. The surefire way to cooking a lamb burger that is both safe and juicy is to check it with a thermometer and incorporate tenderizing ingredients into the meat.
To destroy harmful microbes, the U.S. Department of Agriculture recommends cooking ground lamb patties to a minimum internal temperature of 160 degrees Fahrenheit., which is higher than the recommended 145 F temperature for whole cuts of lamb, such as lamb chops. Since bacteria live on the surface of raw meat, whole pieces of lamb that are thoroughly cooked on the outside are safe to eat. Burgers, in contrast, contains bits of the contaminated surface distributed throughout the ground meat.
At 160 F, lamb typically transforms from red or pink to a gray-brown color. A pink center could indicate that the lamb burger was not cooked to the recommended safe temperature; however, burgers cooked over flames on a wood, charcoal or gas grill sometimes undergo a chemical reaction that creates a permanent pink hue, regardless of how long the burger is cooked. A pink lamb burger that meets the minimum internal temperature is still safe to eat.
Shades of Gray
The absence of a pink color does not guarantee that a lamb burger is cooked through. Other factors besides heat affect myoglobin, the protein that gives raw meat its red color. Exposing meat to light or freezing temperatures for prolonged periods of time denatures the myoglobin, causing it to turn gray. To be certain that the meat reaches 160 F, check the burger with an accurate food thermometer. In restaurants, you can request that your burger is cooked "well-done."
Keep It Juicy
Despite the risk of pathogens, many recipes recommend cooking lamb burgers to "medium," whereby the internal temperature is 145 F, and the inside is typically quite pink. Cooking lamb burgers past this point tends to make them dry and tough. To counteract these negative effects, incorporate tenderizing acidic ingredients into the ground lamb, such as yogurt or wine. A mixture of milk and bread crumbs, called a "panade," is another option that you can incorporate to keep burgers moist and tender.