Behavior of Selected Food-Borne Pathogens in Raw Ground Beef

Abstract

Raw ground beef was inoculated with five strains each of Escherichia coli, enterococci, salmonellae, staphylococci, Bacillus cereus, and Clostridium perfringens. Changes in population levels of these organisms, psychrotrophs, and total aerobic flora as these were influenced by temperature and packaging film were recorded. Among the organisms inoculated, only E. coli, salmonellae, and the enterococci were able to grow and then only at the highest test temperature (12.5 C), As expected, the packaging film did not influence the behavior of any of the test organisms. These results and the fact that a cooking step is involved demonstrate why ground beef is very rarely involved as a vehicle in bacterial food poisoning. This study indicates that there is no reason to expect protection of public health to evolve from bacteriological standards which limit numbers of non-pathogenic organisms.