M01017: Standardisation of sampling and analysis in poultry abattoirs in support of HACCP-based hygiene solutions

Study Duration: October 2001 to September 2004

Contractor: Direct Laboratory Services

The project was commissioned to investigate if standardised microbiological sampling protocols and examination methods suitable for use in poultry slaughterhouses for verification of HACCP could be produced.

• A survey carried out in 20 poultry abattoirs found no widely-used microbiological testing and sampling plans.
• Studies were performed to determine the appropriateness of counting a range of potentially useful process hygiene bacteria (TVC, Enterobacteriaceae, E. coli, Pseudomonas, and coliforms) on poultry carcasses and neck skins in commercial slaughterhouses. Statistical variation was lowest for TVC, Enterobacteriaceae and Pseudomonas in neck skin samples and these were taken forward for further study.
• Samples taken from 18 plants throughout the UK in the summer and winter seasons showed that bacterial numbers (TVC, Enterobacteriaceae, and Pseudomonas) were significantly higher (P <0.05) in summer when compared to winter.
• Bacterial levels on carcases were sampled weekly at a typical medium-to-high throughput plant for almost a year to investigate the possibility of seasonal bias. No seasonal trends, or significant (P <0.05) changes in the bacterial indicator numbers on carcasses were observed despite a wide variety of changes in plant operating cleanliness during this time. Further visits to three other plants were carried out and bacterial numbers determined at periodic intervals after the start of a days processing. Plant cleanliness deteriorated visibly as the days’ processing continued. However no significant changes (P <0.05) to the bacterial numbers were observed with process time.
• The errors associated with the measurement of bacterial numbers for each indicator were calculated from dual analyses of single samples in a laboratory. Errors were lowest overall for TVC. In general, measurement errors were higher when lower bacterial numbers were being measured. Using five neck skin samples at once for microbiological analyses was found not to be significantly different (P <0.05) to the mean of individually-analysed samples. Thus bulking samples together for analyses is appropriate for neck flap samples. Bacterial numbers increased by a factor of ten when stored under chilled conditions similar to those used for sending samples to external analyses laboratories. The increases were not significant (P <0.05) for Pseudomonas and TVC when storage time was less than 17 hours.
• Studies concerning Campylobacter numbers on poultry during processing showed that the draft International Standard method for determining Campylobacter counts is not reliable when low numbers are present. It was also shown that Campylobacter contamination of poultry carcasses in processing plants across the UK is significantly lower (P <0.001) in the winter compared to the summer.

From this study it was concluded that, at the plants visited for this study, there was a poor relationship between bacterial indicator numbers and actual process cleanliness. Consequently bacterial analysis for process verification purposes in poultry slaughterhouses may not be appropriate. The study findings were used as evidence for the removal of some of the proposed microbiological process hygiene criteria for poultry processing plants from EU draft regulation SANCO 4198/2001. ( EC) 2073/2005)
The findings for Campylobacter detection and enumeration have been used in an EFSA working group to develop a harmonised protocol for an EU survey of poultry.

• Hutchison, M. L., Walters, L. D., Allen, V. M., Mead G. C. and Howell, M. (2006). Measurement of Campylobacter numbers in carcasses in British poultry slaughterhouses. Journal of Food Protection 69: 421-424.
• Hutchison, M. L., Walters, L. D., Mead, G. C., Howell, M. and Allen, V. M. (2006). An assessment of sampling methods and microbiological hygiene indicators for process verification purposes in poultry slaughterhouses. Journal of Food Protection 69:145-153.