POTENTIAL FOR GROWTH FROM SPORES OF BACILLUS-CEREUS AND CLOSTRIDIUM-BOTULINUM AND VEGETATIVE CELLS OF STAPHYLOCOCCUS-AUREUS, LISTERIA-MONOCYTOGENES, AND SALMONELLA SEROTYPES IN COOKED GROUND-BEEF DURING COOLING

The ability of 16 foodborne pathogens, representative of 5 different s pecies, to grow during cooling of previously sterilized cooked beef wa s studied to determine a safe cooling rate. Autoclaved ground beef sam ples (3 g) were inoculated with heat-shocked spores of Bacillus cereus (strain BH 86) or Clostridium botulinum (nonproteolytic type B strain s CBW 25, 17B, and KAP B5 and type E strains Whitefish, Saratoga, and Alaska) or vegetative cells of Listeria monocytogenes (strains HO-VJ-S , V-7, and Scott A), Staphylococcus aureus (strains 196E, B121, and B1 24), or Salmonella serotypes (S. dublin, S. enteritidis, and S. typhim urium), vacuum-packaged, and cooked in a stirred water bath to an inte rnal temperature of 60 degrees C in 1 h. In some experiments combinati ons of C. botulinum and B. cereus spores or S. aureus and salmonellae vegetative cells were used. Heated samples were cooled through the tem perature range of 54.4 to 7.2 degrees C at rates varying from 6 to 21 h. Samples were removed at various times during cooling to determine i f growth of the pathogens had occurred. No growth was observed with co oling periods of up to 21 h. This study with the model meat system (3 g autoclaved ground beef inoculated with selected pathogens and then p asteurized) indicated that cooling from 52.4 to 7.2 degrees C in up to 21 h would not pose a food safety hazard from growth of these pathoge ns.