Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2013
Publication Date: 7/28/2013
Citation: Sommers, C.H., Scullen, B.J., Hwang, C. 2013. Gamma radiation inactivation of non-0157:H7 shiga-toxin producing Escherichia coli in foods. Meeting Abstract. IAFP Annual Meeting, Charlotte, NC.,7/28 to 7/31/2013. P1(1). Interpretive Summary:
Technical Abstract: Non-O157:H7 serovars of shiga-toxin producing Escherichia coli are emerging foodborne pathogens that have been associated with illness outbreaks and food product recalls on a global basis. Ionizing (gamma) radiation is a nonthermal food safety intervention technology that has been approved for use in over fifty countries to improve the safety and shelf-life of foods. In this study, the use of gamma radiation to inactivate pathogenic E. coli in foods was investigated. A cocktail of six non-O157:H7 serovars, O26: H11, O45: H2, O103: H2, O111: H11, O121: H19, and O145, or six O157:H7 serovars was inoculated (8 log CFU/g) into ground beef (GB), ground turkey (GT), catfish fillets (CF), or shrimp (SH). Food Samples (10g) were placed in sterile polynylon sample bags, sealed under vacuum and then frozen for 3 min at -59 deg C using a Cryo-Test Chamber by exposing the samples to controlled liquid nitrogen vapor. The samples were then irradiated (0, 0.6, 1.2, 1.8, 2.4, and 3.0 kGy) using a self-contained 137-Cs gamma radiation source (0.074 kGy/min at -20 deg C). Duplicate samples were processed per experiment at each radiation dose, and each experiment was conducted 3 times. Radiation D values (the radiation dose needed to inactivate 1 log of pathogen) for E. coli O157:H7 were 0.47, 0.46, 0.52, and 0.42 kGy in GB, GT, SH, and CF, respectively. The D values for the non-O157:H7 serovars were 0.40, 0.34, 0.41, and 0.38 kGy in GB, GT, SH, and CF, respectively. With the exception of catfish, the D values for the non-O157:H7 serovars were significantly lower (p<0.05) than those for O157:H7. These results indicate that the radiation doses used to inactivate E. coli O157:H7 in these foods can also be used for the non-O157:H7 serovars.