Transfer of Listeria monocytogenes during mechanical slicing of turkey breast, bologna, and salami

• Published in: Journal of food protection Vol. 69; no. 3; pp. 619 - 626
• Main Authors: Vorst, K.L, Todd, E.C.D, Ryser, E.T
• Format: Journal Article
• Language: English
• Published: Des Moines, IA International Association of Milk, Food and Environmental Sanitarians 01.03.2006
• Subjects: Animals; bacterial contamination; Biological and medical sciences; bologna; breast muscle; Colony Count, Microbial; Consumer Product Safety; cross contamination; delicatessen foods; Equipment Contamination; food contamination; Food Contamination - analysis; Food Handling - methods; Food industries; Food Microbiology; food pathogens; food processing equipment; Fundamental and applied biological sciences. Psychology; Humans; Listeria monocytogenes; Listeria monocytogenes - isolation & purification; Meat and meat product industries; Meat Products - microbiology; salami; slicers; turkey meat; Salami; Turkey meat; Meat product; Pork product; Listeria monocytogenes; Transfer; Bacteria; Slicing
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028x-69.3.619

A commercial delicatessen slicer was used as the vector for sequential quantitative transfer of Listeria monocytogenes (i) from an inoculated slicer blade (approximately 10(8), 10(5), or 10(3) CFU per blade) to 30 slices of uninoculated delicatessen turkey, bologna, and salami, (ii) from inoculated product (approximately 10(8) CFU/cm2) to the slicer, and (iii) from inoculated product (10(8), 10(5), or 10(3) CFU/cm2) to 30 slices of uninoculated product via the slicer blade. Cutting force and product composition also were assessed for their impact on L. monocytogenes transfer. Five product contact areas on the slicer, which were identified from residue of product bathed in Glow-Germ, were also sampled using a 1-ply composite tissue technique after inoculated product had been sliced. After being sliced with inoculated blades, each product slice was surface or pour plated on modified Oxford agar and/or enriched in University of Vermont medium. Greater transfer (P < 0.05) occurred from inoculated turkey (10(8) CFU/cm2) to the five slicer contact areas from an application force of 4.5 kg as compared with 0 kg. On uninoculated product sliced with blades inoculated at 10(8) CFU per blade, L. monocytogenes populations decreased logarithmically to 10(2) CFU per slice after 30 slices. Findings for the inoculated slicer blade and product (10(5) CFU per blade or cm2) were similar; L. monocytogenes concentrations were 10(2) CFU per slice after 5 slices and enriched samples were generally negative for L. monocytogenes after 27 slices. For uninoculated product sliced with blades inoculated at 10(3) CFU per blade, the first 5 slices typically produced L. monocytogenes at approximately 10 CFU per slice by direct plating, and enrichments were negative for L. monocytogenes after 15 slices. The higher fat and lower moisture content of salami compared with turkey and bologna resulted in a visible fat layer on the blade that likely prolonged L. monocytogenes transfer. As a result of cross-contamination, those delicatessen-sliced meats that allow growth of L. monocytogenes during prolonged refrigerated storage likely pose an increased public health risk for certain consumers.