2007 Annual Report 1a.Objectives (from AD-416) The objectives of this project are: 1)quantify the degree fo L. monocytogenes transfer during deli slicing of cured ham based on slicer blade composition, blade surface roughness, product temperature and product composition, 2)characterize the prevalence and levels of L. monocytogenes in deli-sliced meats and the likelihood and mechanism of cross-contamination occurring during deli slicing due to specific food service handling behaviors, 3)develop a compartmental mechanistic mathematical risk model of L. monocytogenes associated with the deli slicing process, including cross-contamination, 4)use the model to identify candidate risk mitigation strategies, and 5)develop educational and outreach strategies, including the development of specific risk communication messages, targeting deli slicing machine operators to reduce the risk of contamination and growth of L. monocytogenes. 1b.Approach (from AD-416) The proposed work will involve cooperative research between the MFS and Michigan State University (MSU). Using a combination of laboratory-based studies, mathematical modeling, and communication/education programs, specific data gaps will be filled for the likelihood of L. monocytogenes contamination during the slicing of ready-to-eat meats. These data will be used to revise an existing L. monocytogenes risk assessment targeted at the retail/home handling phase of the farm-to-fork continuum. Subsequent sensitivity and what-if scenario analysis will identify critical variables impacting risk. In response to these findings, risk communication and education strategies/guidelines for consumers and deli workers will be developed. 3.Progress Report 1935-42000-057-12S - This report serves to document research conducted under a General Assistance Type agreement between ARS and the Michigan State University. MSU conducted the Listeria transfer using mechanical slicer and RTE deli meat with consideration of different knives, product compositions (e.g. fat content), etc. MSU proposed to develop the transfer model using an experimental design. The most significant accomplishments to date include: (1) acquisition of four model 2612 Hobart slicers, (including three types of blades) as well as one Berkel slicer (donated by Berkel) that was recently re-designed for enhanced cleanability; (2) set up of the three Hobart slicers and the Berkel slicer at a local delicatessen for one year of use and monthly sampling; (3) identification of the product contact areas on the slicers for sampling; (4) optimization of the blade inoculation method using surface-inoculated ham; and (5) collection of initial data on the potential and extent of sequential transfer of L. monocytogenes from the slicer blade to ham and other areas of the slicer during slicing. ARS has contributed to the measurement of the blade surface profiling of brand new blades and delivered the blades to MSU. All the blades will be re-profiled after one year of use. The blade surface character is one of the key parameters to be used by MSU for model development. The profiling was performed in the ERRC Lab using the Confocus method (led by Dr. Peter Cooke). The monitoring activities included phone calls and receipt of written reports.