Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2009
Publication Date: 5/1/2010
Citation: Mcquestin, O.J., Musgrove, M.T., Tamplin, M.L. 2010. Kinetics of Salmonella enterica serotype Typhimurium DT104 growth and inactivation in pasteurised liquid egg products. Food Microbiology 27:396-402. Interpretive Summary: There is a potential security risk by post-process contamination of liquid egg products which are often transported in bulk. Antimicrobial resistant strains of Salmonella Typhimurium DT104 (ST DT104) can cause salmonellosis of greater severity and longer duration than other Salmonella serotypes, making this strain a greater threat as a potential food security agent. A previous paper generated data that was then used to create potential growth modeling curves for ST DT104 in several liquid egg products. This information will be used by risk assessors to determine the likelihood of ST DT104 in liquid egg products, allowing the prevention of such attacks on national food security or given that the growth rates determined were so slow that other organisms and toxins may be of greater interest for future work.
Technical Abstract: The potential impact of intentional post-pasteurisation contamination of liquid egg products with the multi-antibiotic resistant pathogen Salmonella enterica serotype Typhimurium definitive type 104 (DT104) was assessed by determining the viability of this bacterium in whole egg, albumen and 10% sugared and salted yolk incubated at 4 to 42°C. Results indicated that populations of S. Typhimurium DT104 were slowly inactivated in all four products when stored at 4°C. However, based on the typical shelf-lives of cold-stored liquid egg, less than 0.6 log-kill would be achieved in those products prior to their use. Incubation at temperatures pertaining to abuse situations (10, 15, 20 and 25°C) revealed an increasing potential for growth of S. Typhimurium DT104 in whole egg, albumen and sugared yolk, as indicated by trends in growth rate, lag duration and maximum population density. At even higher temperatures (30, 37 and 42°C), growth rates of S. Typhimurium DT104 in whole egg and sugared yolk continued to increase. The same was true for S. Typhimurium DT104 in albumen except that growth was not observed at 42°C; instead populations were inactivated within 30 h. At no temperature tested was S. Typhimurium DT104 able to grow in salted yolk. The influence of these growth and inactivation patterns on the risk of salmonellosis in relation to product type and storage temperature is discussed with particular reference to the potential for large outbreaks of illness caused by deliberate contamination.