title: Factors affecting thermal resistance of Salmonella enterica serovar enteritidis ODA 99-30581-13 in shell egg contents and use of heat-ozone combinations for egg pasteurization.
abstract: Infection of laying hens with Salmonella enterica serovar Enteritidis leads to deposition of the pathogen into the albumen or yolk of forming eggs. Heat treatment can inactivate internalized Salmonella Enteritidis in shell eggs, but factors such as the nature and location  of contamination may influence the efficacy of thermal treatments. In the current research, natural contamination was mimicked by introducing small inocula of Salmonella Enteritidis into different locations of shell eggs and incubating inoculated eggs. These pathogen-containing eggs  were heated at 57°C for 40 min, and temperature within eggs was monitored at the locations of inocula. Comparison of inactivation at equivalent internal temperatures revealed similar levels of lethality regardless of inoculum location. Refrigeration between incubation and heat treatment  did not increase thermal resistance of cells in albumen but decreased cell inactivation in yolk. Sequential application of heat and gaseous ozone allows for the development of a process capable of decontaminating shell eggs with minimal thermal treatment and impact on egg quality. Inoculated  eggs were subjected to (i) an immersion heating process similar to that used in commercial pasteurization or (ii) immersion heating, at reduced duration, followed by vacuum (50.8 kPa) and treatment with ozone gas (maximum 160 g/m(3)) under pressure (∼187.5 kPa). All treatments  tested produced greater than 5-log inactivation, which is required for "pasteurization" processes. Differences were observed in the visual quality of eggs depending on treatment parameters. Application of ozone subsequent to heating allows for a significant reduction in heating  time without decreasing process lethality.
authors: Department of Food Science and Technology, The Ohio State University, Columbus, OH 43235, USA.
authors: Jennifer J
authors: JJ
authors: Perry
authors: Ahmed E
authors: AE
authors: Yousef
mesh_terms: D000818:Animals; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004528:Egg Shell / Q000382:microbiology; D004531:Eggs / Q000382:microbiology* / Q000592:standards; D005516:Food Microbiology; D010126:Ozone / Q000494:pharmacology*; D061352:Pasteurization / Q000379:methods*; D012477:Salmonella enteritidis / Q000254:growth & development*; D013696:Temperature
chemical_list: D010126:Ozone