Ground beef is one of the most popular forms of red meat consumed in the United States. According to my calculations (as inspired my a mentor of mine), if all of the ground beef consumed in the U.S. per year was made into quarter-pound patties that are about a half-inch thick, then stacked end-to-end, that stack-o-beef could reach from Earth to its Moon (then have to double-back one quarter the distance)!
Any intact, whole muscle (most roasts, steaks, chops) is essentially sterile in the interior, and this is why meat eaters can safely enjoy beef or lamb cooked rare or medium-rare (pork is another issue, especially with new evidence of the re-emergence of Trichinella spiralis in pork that was raised “free-range” — you guessed it, there will be a blog entry on that topic soon). Ground meats, however, have had their exterior surface (which may harbor pathogenic bacteria) exposed to the interior, and thus the potential exists that the whole lot of ground meat may be contaminated. And so, the meat must be cooked thoroughly and completely to kill any ill-doers lurking. Sometimes I hear people say it’s only meat that has been “mixed” (i.e. ground pork + ground beef) that is a safety concern. Nope. This goes for all ground meat — and this should go for all ground meat regardless of how the animal was raised and/or fed.
Moving on. As you’ve read in my previous entries about meat’s fresh color, there are a lot of factors associated with it, and those factors tie in to meat’s cooked color. (It’s a complicated deal, this meat color business.) Cooking meat results in denaturation of myoglobin, its pigment (yes, referring to cooking at “thermal protein denaturation” takes something away from the overall idea of cooking). Because of a host of chemistry factors (again, most of them are completely natural, normal happenings), meat can look cooked, or brown, at a less-than-done and less-than-safe (i.e. @145°F) temperature (this is referred to as “premature browning”), or remain pink at a higher-than-done (i.e. 170°F) temperature (this is referred to as “persistent pinking”). As such, one cannot rely on cooked color to indicate doneness (unless of course you cook like my Grandmother – sorry, Granny – whose philosophy was “when it’s brown it’s cooking, when it’s black it’s done…”). USE A MEAT THERMOMETER!
There is a lot of scientific literature on this subject, and rather than spell this out piece by piece, I refer you to a nicely comprehensive review of this topic as developed by USDA’s Food Safety and Inspection Service. There you can read all about it, as well as gather some other safe handling advice about meat. When eating out, consider exercising caution when the individual taking your order asks, “How‘d like your burger done?” by answering with the question, “How do you monitor doneness?” If the answer is color, maybe you can supply them with a lesson on how one assess ground beef doneness by politely asking that they USE A MEAT THERMOMETER!