Medycyna Wet. 67 (11), 760-764, 2011
full text
| Bełkot Z. |
| Bacterial contamination of chicken carcasses as influenced by the time of slaughter during the |
| The objective of the research was to determine bacterial contamination on the surface of chicken carcasses as influenced by the order in which chickens were slaughtered during the day. The research was conducted on 75 carcasses of chickens aged 6-8 weeks, originating from a plant licensed to trade on the markets of the EU and to export to third countries. The plant complied with the HACCP system and had obtained ISO certificates related to production hygiene. The daily production of the plant amounted to 60 thousand chickens. The plant used an evaporative chilling system. Samples were collected on consecutive days of a production week. Each day, samples were collected three times: at the beginning of production (from the first 1,000 carcasses), in the middle (3,000-31,000 carcasses) and at the end (59,000-60,000 carcasses). A sample for examination consisted of skin removed from the breast and the thigh areas. Directly after chilling, 20 cm2 of skin was collected by a destructive method from each carcass. The number of the following bacteria was determined per 1 cm2 of skin: aerobic bacteria, psychrotrophic bacteria, bacteria from the Enterobacteriaceae family, and Enterococcus faecalis. The presence of Salmonella bacteria was determined in 25 g samples consisting of neck skin tissue from three carcasses. All microbiological examinations were conducted in accordance with Polskie Normy (Polish Standards). The results obtained were expressed as logarithms. The significance of differences was evaluated by Tukey's multiple range test. The total count of aerobic bacteria amounted to 4.78 log CFU/cm2 at the beginning of a slaughter cycle, 5.11 log CFU/cm2 in the middle, and 5.19 log CFU/cm2 at the end. The bacterial contamination of carcasses at the beginning of a slaughter day was significantly lower than contamination in the middle or at the end of the day, between which there was no significant difference. A similar pattern was observed for psychrotrophic bacteria, which numbered 4.56 CFU/cm2 at the beginning of a slaughter cycle, 5.02 CFU/cm2 in the middle, and 5.10 CFU/cm2 at the end. The number of bacteria from the Enterobacteriaceae family amounted to 2.97 CFU/cm2 at the beginning of a slaughter cycle, 3.01 CFU/cm2 in the middle, and 3.16 CFU/cm2 at the end. No significant differences in contamination with this group of micro-organisms were observed between the three batches of samples. There were also no significant differences in contamination with Enterococcus faecalis. The number of bacteria from the Enterococcus family amounted to 3.28 CFU/cm2 at the beginning of a slaughter cycle, 3.33 CFU/cm2 in the middle, and 3.38 CFU/cm2 at the end. Salmonella bacteria were found on the skin of chickens from all three batches of samples collected during a slaughter day. They were detected in 7 samples (28%) collected at the beginning and at the end of a production day, and in 6 samples (24%) collected in the middle of the day. The predominant serotype was S. Enteritidis, but S. Virchow was also found in two samples collected at the beginning of a production day. The order in which chickens were slaughtered during a slaughter day had a significant influence on the general level of bacterial contamination and on the level of contamination with psychrotrophic bacteria. Carcasses of chickens slaughtered at the beginning of a production day were characterized by a lower general level of contamination, including contamination with psychrotrophic bacteria, compared with carcasses produced later during the day. No such pattern was observed for contamination with bacteria from the Enterobacteriaceae family and Enterococcus faecalis. Salmonella bacteria were detected in 27% of carcasses examined. The time of slaughter did not appear to have any significant effect on contamination with these bacteria. |
| Keywords: slaughter chickens, the order of animals slaughtered, bacterial contamination, Salmonella |