The effect of processing procedures and overall environmental and hygienic conditions on the microbiological quality and safety of chicken carcasses was studied in a modern processing plant on two separate days. The level of microorganisms on chicken carcasses was assessed by a neck-skin “maceration” method. Carcasses were heavily contaminated by different types of organisms, including indicator organisms (total aerobics, Enterobacteriaceae, coliforms and Escherichia coli) and pathogens (e.g., Salmonella, Campylobacter and Staphylococcus aureus). Microbial levels varied during processing, but the highest levels were detected after scalding and defeathering. Microbial levels did not change during vent opening or evisceration.
Spray washing after evisceration did not reduce levels of bacteria. No substantial change occurred in bacteria levels during air-chilling, packaging and cold-storage; however, the finished product was heavily contaminated. In the freshly processed carcasses, mean counts (log colony forming units [CFU]/g neck-skin) of aerobic bacteria Enterobacteriaceae, coliforms, E. coli, Campylobacter and S. aureus were 6.6, 4.5, 4.1, 3.6, 5.2 and 2.7 on the first sampling day, and 6.5, 4.6, 4.9, 3.6,4.7 and 4.1 on the second day. Salmonella was present in all birds examined, including those coming directly from the farm. Major serotypes detected on dressed carcasses were Salmonella ohio, Salmonella enteritidis, Salmonella paratyphi and Salmonella krefeld.