It’s a logical question. Why does the USDA recommend that ground meat be cooked well done but generally deem it okay to cook steaks and roasts medium rare? After all beef is beef, isn’t it? That’s true but when it’s ground, the rules change, for your own safety.
Bacteria, which include E.coli and Salmonella is literally everywhere, and can contaminate beef (or any food) at any point along the supply chain. Even at home through cross-contamination. It’s likely the surface area of steaks and roasts can harbor bacteria even after USDA inspection.
In small amounts most bacteria are relatively harmless. but bacteria can multiply at a rapid rate under certain conditions such as meat being stored at temperatures that are above 40 degrees Fahrenheit. This is particularly true when meat is exposed to warmer temperatures for 2 hours or more.
Since bacteria will mostly contaminate only the surface or near surface area of steaks and roasts, high cooking heat will kill bacteria. Therefore, steak cooked medium-rare is relatively safe since surface area bacteria would be eradicated. However, steaks that are cooked rare could still be somewhat suspect. That’s why restaurants warn diners that eating under-cooked steaks could expose them to harmful food borne bacteria.
Why Hamburger is Vulnerable
Hamburger and ground meat are cuts of beef that are processed through a grinder. If the cut of meat has been contaminated with bacteria it would reside on the meat surface or near surface. When ground, any bacteria will be uniformly distributed within the ground mixture.
Therefore, the entire product would be contaminated with active harmful bacteria. The only way to ensure all food borne bacteria is killed is cooking the hamburger or ground meat to an inside temperature of 165 degrees Fahrenheit which is required temperature to achieve well done.
BE SAFE. Cook all hamburger and ground beef well done.
USDA Ground Beef Safety
Importance of Cold Storage
Safe Freezing of Meat
Ground Beef Safety