Attachment of Salmonella typhimurium to the skin of turkeys that had been processed through three different defeathering systems (conventional, kosher, and steam-spray) was examined at varying incubation times (10~60 min) using scanning electron microscopy. The extent of attachment varied with the type of defeathering method and increased with incubation time. Conventional and kosher skins showed slow rate of attachment, whereas steam-spray skin allowed a sharp increase of attachment, due to the collagenous connective tissue of dermis exposed during processing. Exposed dermis in kosher skin revealed the very adhesive properties of dermis. Attachment fibrils appeared as incubation time increased. Cells on steam-spray skin produced a considerable amount of long, thin fibrils connecting them to each other and to the skin after 30 min of incubation. While a few thick and short attachment fibrils were observed in conventional skin, no fibrils were detected in kosher skin. The high number of attached cells and the greatest amount of fibril formation on the surface of steam-spray skin suggest the positive relationship between bacterial attachment and fibril formation. Depressions produced by attached cells were observed in conventional skin surface, but not in kosher skin, probably due to the fatty and pliable properties of conventional skin. Pits, observed only on the surface of steam-spray skin, reflected the weak property of basal membrane covering the dermis. The above results suggest that exposing dermis is undesirable for reducing bacterial attachment during poultry processing.
1 Current address: Department of Poultry Science, University of Arkansas, Fayetteville, Arkansas 72701