ARS | Publication request: Modeling Surface Cross-contamination of Salmonella spp. on Ready-to-Eat Meat via Slicing Operation

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 6, 2009
Publication Date: June 6, 2009
Citation: Sheen,S.2009.Modeling Cross-contamination of salmonella spp. on Ready-to-Eat meat via slicing operation[abstract].Institute of Food Technology's Annual Meeting.Anaheim,CA.p.1.

Technical Abstract: Food pathogen cross-contamination occurring at home, retail food service or production site is one of the major factors causing foodborne illness. Studies on Salmonella Typhimurium surface transfer on ready-to-eat (RTE) deli meat and the slicer used for slicing RTE products are needed to ensure RTE food safety with respect to this pathogen. The objectives of this study were to investigate and to model the surface cross-contamination of Salmonella during slicing operation. A five-strain cocktail of Salmonella Typhimurium was inoculated directly onto a round slicer’s blade rim area at an initial level of ca. 4, 5, 6, 7, 8 or 9 log CFU/blade (ca. 3, 4, 5, 6, 7 or 8 log CFU/cm-squared of the blade edge area). Thereafter, the RTE deli meat (ham) was sliced to a thickness of 1-2 mm. For another cross-contamination scenario, a clean blade was initially used to slice ham which was pre-surface-inoculated with Salmonella cocktail (ca. 2, 3, 4, 5, 6 or 7 log CFU/cm-squared with a total area of 100 cm-squared), followed by slicing un-inoculated ham. Empirical models were developed. These models were accurate in describing the surface transfer trend/pattern of Salmonella between the blade and ham slices when the total inoculum level was equal to or greater than 5 log CFU on the ham or blade. With an initial inoculum level equal to or less than 4 log CFU, the experimental data showed a rather random microbial surface transfer mode. Overall, the developed non-linear models, which depend on microbial load and sequential slice index (operation time related), showed the F-statistic test result was highly significant (i.e. P greater than F (less than 0.0001)) and the r-squared value was equal to 0.70. The models predict the surface cross-contamination of Salmonella Typhimurium (at any initial level) for sliced deli meat (ham) and will provide a useful tool in developing the RTE meat risk assessment.