PENETRATION OF SALMONELLA-TYPHIMURIUM INTO TURKEY SKIN

Penetration of Salmonella typhimurium into the turkey skins from three different defeathering systems (conventional, kosher, and steam-spray ) was quantified by transverse sectioning of inoculated skins with a c ryostat and fluorescent antibody staining of skin section homogenates. The microtopography of each skin observed by transmission electron mi croscopy was correlated with cell penetration. Although few cells were recovered due to freeze injury or freeze killing, direct plating of s kin section homogenates showed the different properties of each skin f or cell penetration. Fluorescent antibody staining recovered the most cells and revealed the cell distribution within the skin. In conventio nal skin, over 90% of cells resided in the upper 50 mum depth of skin, which implies the poor penetration of cells. Kosher skin showed relat ively even distribution of cells up to 150 mum in depth, which indicat ed the penetration of cells even into the dermis. Steam-spray skin all owed the deepest (over 200 mum depth) and the highest number of penetr ation among the three types of skin. Conventional skin retained a thin layer of epidermis (0.3 approximately mum of stratum germinativum) on the surface, and it appeared to act as an effective physical shield a gainst bacterial invasion. The loss of all epidermis on steam-spray sk in could explain the deep penetration following this process. Kosher s kin retained the most epidermis; however, the characteristic lengthy p icking time in kosher processing caused mechanical damage to the skin and allowed deep penetration of cells.