Enumeration of Salmonellae in Table Eggs,Pasteurized Egg Products,and Egg-Containing Dishes by Using Quantitative Real-Time PCR |
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| Authors: | D?iuginta Jako?iūn? Frédérique Pasquali Cristiana Soares da Silva Charlotta L?fstr?m Jeffrey Hoorfar Günter Klein Gerardo Manfreda John Elmerdahl Olsen |
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| Institution: | aDepartment of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark;bDepartment of Veterinary Medical Sciences, University of Bologna, Ozzano Emilia, Bologna, Italy;cInstitute of Food Quality and Food Safety, University of Veterinary Medicine, Hannover, Germany;dNational Food Institute, Technical University of Denmark, Søborg, Denmark |
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| Abstract: | Salmonellae are a major cause of food-borne outbreaks in Europe, with eggs and egg products being identified as major sources. Due to the low levels of salmonellae in eggs and egg products, direct quantification is difficult. In the present study, enrichment quantitative real-time PCR (qPCR) was employed for enumeration of salmonellae in different matrices: table eggs, pasteurized egg products, and egg-containing dishes. Salmonella enterica serovar Enteritidis and S. enterica serovar Tennessee were used to artificially contaminate these matrices. The results showed a linear regression between the numbers of salmonellae and the quantification cycle (Cq) values for all matrices used, with the exception of pasteurized egg white. Standard curves were constructed by using both stationary-phase cells and heat-stressed cells, with similar results. Finally, this method was used to evaluate the fate of salmonellae in two egg-containing dishes, long egg and tiramisu, at abused refrigeration temperatures, and results indicated the growth of bacteria over a 1-week period. In conclusion, enrichment qPCR was shown to be reliable for enumeration of salmonellae in different egg products. |
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