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Efficacy of pulsed-UV light treatment inactivating Escherichia coli O157:H7 and Listeria monocytogenes on raw salmon
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Paper number 046021, 2004 ASAE Annual Meeting . @2004
Authors: Nil P. Ozer, Ali Demirci
Keywords: Salmon fillet, Pulsed UV-light, decontamination, E. coli O157:H7, and L. monocytogenes
Several technologies have been investigated to eliminate pathogenic microorganisms on seafood. However, they may not be completely effective in eliminating these pathogens, or they may change the color, flavor, or texture of the seafood. Pulsed UV-light has a potential to eliminate pathogens while preserving the quality. Pulsed UV-light treatment is more effective and rapid than continuous UV-light. The use of pulsed UV-light to inactivate of Escherichia coli O157:H7 and Listeria monocytogenes Scott A on salmon fillets was investigated in this study. Skin and muscles of fillets were inoculated with either of the pathogenic microorganisms. In order to study the effect of distance from the UV strobe on inactivation E. coli O157:H7 and L. monocytogenes Scott A, salmon fillet sample (3 cm x 1.5 cm) in Petri dish was placed in the treatment chamber at 3 different distances from the UV strobe; 3, 5, and 8 cm. At each distance, the pulsed UV-light treatment was performed for 15, 30, 45, and 60 s. For E. coli O157:H7, maximum log reduction was 1.09 log10 CFU/g on skin side at 8 cm for 60-sec, whereas 0.86 log10 CFU/g reduction on skin at 5 cm for 30-sec. For L. monocytogenes Scott A, maximum reduction was 1.02 log10 CFU/g at 8 cm for 60-sec treatment on skin side, whereas 0.74 log10 CFU/g reduction on skin at 8 cm for 60-sec. The salmon's surface temperature was increased with treatment time up to 85oC. Therefore, some samples were overheated after 30, 45, and 60 sec at 3, and 5 cm distance from light source, respectively, which resulted in color and quality changes. Overall, this study demonstrated that one log10 reduction (~90%) of E. coli O157:H7 could be achieved at 60-sec treatment at 8 cm distance, whereas one log10 reduction (~90%) of L. monocytogenes Scott A could be achieved at 60-sec treatment at 8 cm distance without affecting the quality.
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