So it’s important to cook hamburgers thoroughly. Here are some tips from the National Cattlemen’s Beef Association for handling and cooking burgers:

• Purchase meat last when shopping to ensure that it stays as cold as possible.
• Choose packages that are cold and tightly wrapped without tears or punctures.
• Check the package for the "sell by" date, and make sure that date hasn’t passed.
• Store ground beef in the coldest part of the refrigerator, and use or freeze within 2 days. Ground beef can be frozen in its original transparent packaging for up to 2 weeks. To freeze ground beef for up to 4 months, rewrap tightly in heavy-duty aluminum foil, or place in food-safe plastic freezer bag. Press out as much air as possible before freezing.
• Defrost frozen ground beef in the refrigerator (never at room temperature) to prevent bacterial growth. Allow about 24 hours to defrost a 1- to 1 1Ú2-inch-thick package.
• Wash hands with hot, soapy water before and after handling raw meat. Also, wash any surface or utensils that raw meat has touched.
• Cook burgers until the centers are no longer pink and the juices show no pink color. Brush brown sauces such as teriyaki, Worcestershire or soy sauce on the uncooked surface of the patties. When these types of sauces are mixed into the ground beef, it may be difficult to determine doneness.
• Use an instant-read thermometer, if possible, to check the internal temperature of burgers, of 160 degrees. Insert the stem of the thermometer horizontally into the center of the patty, without touching the grill. Allow 10 to 15 seconds for the temperature to register. It should read at least 160 degrees.