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Radiation D10-Values on Thawed and Frozen Catfish and Tilapia for Finfish Isolates of Listeria monocytogenes

Rajkowski, Kathleen T.
Journal of food protection 2008 v.71 no.11 pp. 2278
catfish, tilapia (common name), Ictalurus punctatus, farmed fish, frozen fish, thawing, raw fish, isolation, Listeria monocytogenes, food pathogens, bacterial contamination, food irradiation, food preservation
With the popularity of catfish and tilapia in the healthy diet, the consumption and harvesting of farm-raised finfish have increased. Since 1987 the pathogenic bacterium Listeria monocytogenes has been isolated from seafood, particularly farmraised catfish in the United States. Seafood isolates of L. monocytogenes are now available. In order to maintain the raw finfish product, nonthermal interventions to remove bacterial pathogens need to be evaluated using these isolates. A nonthermal intervention process, irradiation, was used to determine the destruct values of the L. monocytogenes seafood isolates along with a nonpathogenic Listeria strain and an L. monocytogenes strain previously studied. The irradiation destruct values were obtained for each individual isolate inoculated on raw and frozen catfish or tilapia irradiated at 4 or 10 °C. The D(radiation) values obtained for L. monocytogenes inoculated on raw or frozen catfish did not differ (P > 0.05) from the values obtained for strains inoculated on the raw or frozen tilapia. The D(radiation)-values ranged from 0.48 to 0.85 kGy, with an average of 0.62 +/- 0.09 kGy, which is typical for Listeria. The data obtained have identified a multi-isolate cocktail that can be used for future radiation inactivation studies for L. monocytogenes inoculated on finfish.