Use of capillary tubes and plate heat exchanger to validate U.S. Department of Agriculture pasteurization protocols for elimination of Listeria monocytogenes in liquid egg products.
D-values for a five-strain cocktail of Listeria monocytogenes in five different liquid egg products (whole egg, egg yolk, egg white, egg yolk + 5% sucrose + 5% NaCl, and egg yolk + 10% NaCl) were determined using 100-microl capillary tubes. The egg products were inoculated with approximately 1 x 10(10) organisms/ml and heated in capillary tubes to temperatures ranging from 53 to 69 degrees C for various time intervals. Using a pilot scale plate heat exchanger, the U.S. Department of Agriculture (USDA) protocols for pasteurization were also evaluated using egg products inoculated with approximately 1 x 10(7) L. monocytogenes/ml. Results of experiments with capillary tubes suggested that all processes would result in less than the 9D process recommended by USDA. Moreover, although pasteurization with a plate heat exchanger provided greater lethality than did capillary tubes, all products still received less than a 5.4D process. Hence, these results suggest that the current USDA protocol may not be adequate to assure a large margin of safety.
Center for Food Safety and Quality Enhancement, University of Georgia, Griffin 30223, USA.
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Michalski
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Brackett
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Hung
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Ezeike
D000818:Animals; D019411:Clinical Laboratory Techniques / Q000592:standards; D004531:Eggs / Q000382:microbiology*; D005516:Food Microbiology; D006358:Hot Temperature; D006801:Humans; D007881:Legislation, Food; D008089:Listeria monocytogenes / Q000254:growth & development*; D014481:United States; D016885:United States Department of Agriculture