Raw ground beef can harbor harmful bacteria that multiply rapidly when the meat's temperature is between 40 and 140 degrees Fahrenheit. For safety and to maintain freshness, never leave ground beef at room temperature for more than two hours. If the ambient temperature is above 90 F, do not leave it out for more than one hour. These food safety guidelines apply to both raw and cooked ground beef.

Tempting as it may be to leave a package of frozen ground beef on the counter to thaw, this method will encourage the growth of harmful bacteria. The safest way to thaw ground beef is to thaw it in the refrigerator, although this may take several days, depending on the volume of meat. Alternatively, you can place the package in a bowl of cold water and change the water every 30 minutes until the meat is thawed. You may also defrost it in the microwave, although this can result in partially cooking the outside and compromising the texture of the meat. If you're thawing in cold water or the microwave, you must cook the beef straight away.

Store raw ground beef in its original package for up to two days, or in the freezer for up to four months. For best quality when freezing, wrap the original container of ground beef with aluminum foil or plastic wrap, or place it in a resealable freezer bag, to minimize freezer burn. Cooked ground beef can be stored in an airtight container in the refrigerator for up to four days or in the freezer for up to three months.

Discard your ground beef if it's been out at room temperature for more than two hours, or after one hour on hot days. Other indicators that ground beef has gone bad include a gray or brown color throughout -- not just inside, which is normal -- and/or a sour smell. Frozen ground beef should be discarded if it has freezer burn, which shows as dull white patches, covering too much of the beef to be reasonably cut off.