Chicken food chain analysis
Campylobacteriosis is the most frequent source of foodborne illness in the UK and in surveys is frequently associated with chickens and chicken meat.
High level analysis therefore identified campylobacter in the chicken food supply chain as a priority for detailed food chain analysis. A team, drawing on expertise across the agency, reviewed risks and controls through the chicken food supply chain to identify:
- sources of risks and understand how risk varies through the food chain
- points in the food chain where breakdowns in food safety have a key impact on public health
- potential options for reducing the risk, and/or improving the alignment of controls to risks
Evidence on microbiological hazards (summarised in the document that can be downloaded at the end of this page) highlighted that current controls were not effective in reducing the risks associated with this pathogen, which is introduced into the food supply chain at primary production stage (around 70% of flocks are contaminated1). This contamination spreads through the slaughterhouse2 and persists at high levels right through the food chain, with 65% of raw chicken still contaminated at retail.3
There is also strong evidence that campylobacter spreads from chicken onto other foods through cross-contamination and that campylobacter is frequently isolated both in catering and domestic kitchens.4 Evidence indicates that it is cross-contamination of ready-to-eat foods, rather than undercooking of chicken meat, that poses the greatest public health risk. A small survey (n=30) found cooking chicken reduced prevalence of campylobacter from 80% to 5%, and some of the residual contamination was attributed to cross-contamination from surfaces after cooking.
The analysis identified four main areas for potential control of campylobacter in chicken:
- prevent infection and spread at primary production
- prevent contamination of carcases at defeathering and evisceration
- decontaminate carcasses post evisceration
- prevent cross-contamination of other foods
Using these headings, the team then identified a wide range of control options from a combination of existing literature, research and international comparisons. Examples of options showing reductions in experimental research include steps to prevent faecal leakage during processing5 and the use of steam washes.6 International comparisons identified a range of practices from freezing of contaminated carcasses in Iceland to the strategy in New Zealand that is focussed on setting standards for slaughterhouses bases on carcass contamination rates and monitoring performance against these, taking escalating levels of enforcement action when standards are not met. More innovative ideas were also explored with in-house experts including the use of bacteriophages in animal feed or as treatment during processing, and ideas for reengineering the poultry slaughter process.
These options were assessed in terms of their likely impact on campylobacter contamination and whether this would feed through the supply chain; the feasibility of implementing the option including current legislative constraints, cost issues and likely take up; the timing and how much progress could be made during the current strategic planning period; and any risks associated with the option, such as if it would have an impact on other pathogens or hazards.
- There are few control options currently available at primary production so short to medium term delivery of significant public health gains therefore need to focus on later in the food chain. Options around reducing the contamination of carcasses and the spread of pathogens at slaughter and cross-contamination right through the food supply chain are most efficient in bringing public health gains.
- A number of options used in combination (such as consistent application of good hygiene practice, HACCP and correct calibration of processing equipment) have the potential to reduce the campylobacter load on chicken meat. However, to achieve a step reduction in the risk from campylobacter a more radical approach would be required.
- Based on the options currently approved for use in the UK, the recommendation for achieving a significant reduction in campylobacteriosis was to work with industry to agree standards that lead to a reduction in the level of contamination on chicken and work in partnership with industry in taking necessary actions to ensure the agreed standards are achieved. The Agency's foodborne disease strategy is currently being refreshed and these recommendations will be reviewed in that process.
1. Bull et al (2003), Studies to identify critical points for infection of live birds or contamination of poultry carcases with campylobacter and salmonella species (B03008).
2. H. Rosenquist et al (2006), The effect of slaughter operations on the contamination of chicken carcasses with thermotolerant Campylobacter, 'International Journal of Food Microbiology' 108, p226-232 (a Danish study).
3. FSA report for the UK survey of campylobacter and salmonella contamination of fresh chicken at retail sale (B18025).
4. Harrison et al (2001), Determining Exposure Assessment and Modelling Risks Associated with the Preparation of Poultry products in Institutional Catering and the Home (B01015).
5. M.T. Musgrove et al (1997), Effect of Cloacal Plugging on Microbial Recovery from Partially Processed Broilers, 'Poultry Science' 76 p530–533.
6. C. James et al (2007), Decontamination of poultry carcasses using steam or hot water in combination with rapid cooling or freezing of carcass surfaces. 'International Journal of Food Microbiology' 114 p195-203.
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