Good article, and nice primer on food...
Excerpt:
“Each package consisted of the meat from at least four different cows, and sometimes from as many as eight,” says microbiologist Mansour Samadpour, whose IEH Laboratories did the analysis.
Cargill’s contaminated patties were made by grinding beef trimmings from at least three sources: the giant slaughterhouse Greater Omaha Packing, a facility in Texas that slaughters older dairy cows and bulls, and a slaughterhouse in Uruguay where USDA inspectors later found improper testing for E. coli.
The trimmings were combined with a meat mash made by a South Dakota plant. The facility warms fatty meat scraps, centrifuges away much of the fat, and treats what’s left with ammonia to kill E. coli, according to a New York Times investigation last fall.
The U.S. Department of Agriculture doesn’t require companies to test their foods—or the raw materials that go into them—for E. coli O157:H7. And Cargill, like many other meat processors, didn’t test the trimmings or mash before mixing them together.
That explains why the company and the USDA never figured out how the E. coli got into the frozen patties. In the weeks leading up to the outbreak, USDA inspectors did find unsanitary conditions in the Cargill plant, according to the Times. They reported seeing large numbers of patties on the floor, grinders encrusted with old bits of meat, and a worker who routinely dumped inedible meat on the floor close to a production line.
Full Article... http://www.cspinet.org/nah/articles/cautio... 
