The microtopography of turkey skin resulting from three different defeathering systems and consequent effect of skin microtopography on the adhesion of Salmonella typhimurium were examined. Turkeys from common flocks were scalded and picked using conventional, kosher, and steam-spray systems. Breast skin was subsequently removed, irradiated to eliminate the resident microflora, then inoculated with S. typhimurium for 30 min. Scanning electron microscopy (SEM) and light microscopy revealed that three processes caused different skin microtopographies, which resulted in different amounts of bacterial adhesion. Conventional skin had a comparatively smoother surface and less bacterial attachment. Kosher skin was very rough with a scaly keratinized epidermis and showed little bacterial attachment. Steam-spray skin had a highly convoluted surface (probably with underlying collagen fiber bundles) and showed three times higher attachment of cells than conventional and kosher skins. Contrary to counts of attached cells obtained by scanning electron microscopy, plate counts of all inoculated skins were similar and increased linearly with increasing inoculum concentration. The highest Sm value (an indirect measurement of attachment strength) of kosher skin reflected deep penetration/entrapment of cells within the skin rather than strong attachment of cells, whereas the high Sm value of steam-spray skin would reflect the strong attachment of cells to the specific receptors in the skin. The lowest Sm value and much bigger cell size of S. typhimurium on conventional skin reflected loose bacterial attachment and different surface properties, respectively.

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