SURVIVAL OF LISTERIA-MONOCYTOGENES, YERSINIA-ENTEROCOLITICA AND ESCHERICHIA-COLI O157-H7 AND QUALITY CHANGES AFTER IRRADIATION OF BEEF STEAKS AND GROUND-BEEF

Beef steaks and ground beef were inoculated with Listeria monocytogene s, Yevsinia enterocolitica, or Escherichia coli O157:H7. Samples were packaged in air or under vacuum and irradiated at low (0.60 to 0.80 kG y) or medium (1.5 to 2.0 kGy) doses, with each dose delivered at eithe r a low (2.8 M/min conveyor speed) or high (6.9 M/min) dose rate. Medi um-dose irradiation accompanied by 7 degrees C storage resulted in no Y. enterocolitica or E. coli O157:H7 survivors being detected. There w as no effect on survival of the pathogens by dose rate or storage atmo sphere. No difference (P>0.05) was observed in meat pH or color, but T EA values increased after 7 days storage.