To help improve tenderness of some cuts of beef, the cuts of meat are mechanically tenderized. This means needles or sharp blades are inserted to break up the meat muscle fibers.
This type of tenderizing can increase the risks of bacteria on the surface of the meat to be pushed inside the meat. If not cooked properly, the bacteria could lead to foodborne illness.
The USDA now requires new labels for these products to give safe cooking instructions to consumers. For more information, see http://1.usa.gov/1VXZj8v.