1. Inactivation of Listeria monocytogenes, E. Coli O157:H7 and Salmonella in Frozen Ground Beef Patties by Electron Beam Irradiation ABC Research Corporation James “Ken” Kennedy, Ph.D. Director, Research Microbiology.

2. Objective To determine the inactivation rates and reduction of Listeria monocytogenes, Salmonella typhimurium and E. coli O157:H7 in Vacuum Packaged, Frozen Ground Beef Patties by doses of 1.1 to 4.4 kyG of electron beam irradiation.

3. Methodology Product: Ground Beef (15% fat) fabricated at Univ.of Florida Department of Animal Sciences Inoculated, formed into patties, frozen, vacuum and shrink packaged at ABC Research Corp. Test Microorganisms: Listeria monocytogenes (ATCC 19115, Serotype 4B) Salmonella typhimurium (ATCC 14028) E. coli O157:H7 (MF1847)

4. Methodology Methodology continued Sample Inoculation/Preparation: Each microorganism separately inoculated into product at high (10,000-1,000,000/g) or low (10-10,000/g) levels Product formed into patties, frozen and vacuum/shrink packaged in an irradiation approved barrier film Irradiation Treatment: Frozen patties irradiated by e-beam at “Florida Accelerator Services and Technology,” Gainesville, FL Irradiation dosages of 1.1, 2.2, 3.3, or 4.4 kGy via one to four passes through the irradiation unit

5. Inactivation of Low Inoculum Levels of Pathogens Counts (per gram) Dose (kGy) Listeria Salmonella E. coli monocytogenes typhimurium O157:H7 020 -1,600 30 - 380 30 - 45,000 1.1 <10 <10 <10 - 50 2.2 <10 <10 <10 3.3 <10 <10 <10 4.4 <10 <10 <10

6. Pathogen Reductions Pathogen Reductions (High Inoculum Level) Percentage (%) Reductions 1.1 kGy 2.2 kGy Listeria monocytogenes 86.8 - 97.2 >98.2 - >99.97 Salmonella typhimurium 82.2 - 99.0 >99.0 - >99.94 E. coli O157:H7 98.5 - 99.9 >99.96 - >99.998

7. Pathogen Reductions Pathogen Reductions (Low Inoculum Level) Percentage (%) Reductions 1.1 kGy 2.2 kGy Listeria monocytogenes >56.3 - >99.4 > 56.3 - >99.4 Salmonella typhimurium >67.6 - >97.4 >67.6 - >97.4 E. coli O157:H7 >67.6 - 99.9 >67.6 - >99.98

8. Summary of Pathogen Inactivation Rates Microbial inactivation quantitatively described by: D 10 value  dose in kiloGrays required to inactivate 90% of the microbial population D 10 -Values (kGy) in Raw Red Meats NCBA Gr. Beef Study Literature Listeria mono. 0.72 - 1.25 0.45 - 1.21 Salmonella 0.69 - 1.18 0.55 - 1.28 E. coli O157:H7 0.38 - 0.60 0.24 - 0.88

9. Conclusion Electron beam irradiation was effective in reducing pathogen levels in frozen ground beef patties at low doses (1.1 – 2.2kGy) and may serve as an additional intervention method to enhance the safety of fresh ground beef products.