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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 . Objective.
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Inactivation of Listeria monocytogenes,E. Coli O157:H7 and Salmonellain Frozen Ground Beef Pattiesby Electron Beam Irradiation ABC Research Corporation James “Ken” Kennedy, Ph.D. Director, Research Microbiology .
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.
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)
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
Inactivation of Low Inoculum Levels of Pathogens Counts(per gram) Dose(kGy)Listeria Salmonella E. coli monocytogenes typhimurium O157:H7 0 20 -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
Pathogen Reductions(High Inoculum Level) Percentage (%) Reductions 1.1 kGy2.2 kGy Listeria monocytogenes86.8 - 97.2 >98.2 - >99.97 Salmonella typhimurium82.2 - 99.0 >99.0 - >99.94 E. coli O157:H798.5 - 99.9 >99.96 - >99.998
Pathogen Reductions(Low Inoculum Level) Percentage (%) Reductions 1.1 kGy2.2 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
Summary of PathogenInactivation Rates • Microbial inactivation quantitatively described by: D10 value dose in kiloGrays required to inactivate 90% of the microbial population D10-Values (kGy) in Raw Red Meats NCBA Gr. Beef StudyLiterature Listeria mono. 0.72 - 1.25 0.45 - 1.21 Salmonella 0.69 - 1.18 0.55 - 1.28 E. coli O157:H70.38 - 0.60 0.24 - 0.88
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.