ATTACHMENT OF SALMONELLA-TYPHIMURIUM TO SKINS OF CHICKEN SCALDED AT VARIOUS TEMPERATURES

Microtopography of chicken skin was studied by varying scalding temper ature to determine the least favorable skin surface for salmonellae at tachment. Birds were scalded at 52, 56, and 60-degrees-C, and the chan ges of skin morphology were examined by light and transmission electro n microscopy throughout the whole processing. Breast skins obtained im mediately after picking were inoculated with Salmonella typhimurium, a nd the attachment was quantified by using scanning electron microscopy and microbiological plating techniques. Skins scalded at 52 and 56-de grees-C retained most of the epidermis, although the latter temperatur e caused the loss of twice as much stratum corneum layers and produced a smoother surface than the former. Skins at 60-degrees-C began to lo se most of epidermal layers during scalding and exposed dermal surface after picking, which was sometimes covered with thin fragmental epide rmis or basal tissue. The number of salmonellae attached to 60-degrees -C-processed skins was 1.1-1.3 logs higher than diose attached to the skins processed at 52 and 56-degrees-C, as measured by scanning electr on microscopy. Microbiological plating, however, showed no significant difference in attachment among three skins processed at different tem peratures. This was probably due to the insensitivity of the plating m ethod to differentiate attachment strengths of salmonellae to the skin . The above results suggest that removal of whole epidermis should be avoided in processing to reduce salmonellae attachment to the skin.