Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/23/2002
Publication Date: 10/1/2002
Citation: Murphy, R.Y., Berrang, M.E. 2002. Thermal lethality of salmonella senftenberg and listeria innocua on fully cooked and vacuum packaged chicken breast strips during hot water pasteurization. Journal of Food Protection. 65:1574-1579. Interpretive Summary: Salmonella and Listeria are bacteria that can cause foodborne disease. It may be possible for bacteria to contaminated meat between the commercial cook step and packaging. This would result in a fully cooked meat product that is not safe for some consumers. In this study, marker strains of Salmonella and Listeria were place on the surface of fully cooked chicken breast strips in order to examine the use of a second heat treatment applied after packaging to kill bacteria. Salmonella and Listeria were eliminated from « lb packages after 20 minutes at 88 C, and from 1 lb packages after 34 min. at 88 C. An equation was derived that can be used to calculate the time necessary to achieve acceptable levels of bacterial death in packages of differing weights. These data can be used by commercial processors to design effective post packaging pasteurization systems.
Technical Abstract: Seven log**10 cfu of S. Senftenberg or L. innocua were surface inoculated on fully cooked chicken breast strips. The inoculated strips (227 or 454 g) were vacuum packaged in 0.2 mm thick pouches (114 x 114 mm or 241 x 114 mm). The products were then heat treated in a hot water cooker at 88 C for a time of 0 - 40 min. After heat treatment, S. Senftenberg and L. innocua surviviors were enumerated. Increasing treatment time increased the thermal lethality for S. Senftenberg and L. innocua. The effect of treatment time interacted with product size. In order to achieve 7 log10 reduction for S. Senftenberg and L. innocua, the 454 g packages needed to be heat-treated for 34 min and the 227 g packages needed to be treated for 20 min. Models were developed to correlate treatment time with bacterial survival rate and could be used to predict up to 7 log**10 reduction of S. Senftenberg or L. innocua for similar products.