Food safety is consistently almost among the top priorities in consumer surveys often even ahead of price and it is the constant preoccupation of many involved in the industry, particularly researchers and poultry plant managers and personnel. These two groups came together in September last year for the 18th European Symposium on the Quality of Poultry Meat. The conference was held in Prague and organised by the Czech branch of the World's Poultry Science Association.
Food safety in the poultry chain
Dr Fredi Schwägele from Germany's Federal Research Centre for Nutrition and Food gave an introduction to the topic of poultrymeat safety with a presentation describing two approaches to food safety in the poultrymeat chain. As he explained, European consumers are fortunate to have a choice of a wide range of safe and high quality food products but food scares continue to occur from time to time. These underline the importance of traceability, a system that links products to their source, identify components, counteract fraud and ensure proper processing has taken place. Clearly, this requires a thorough understanding of the working of the food chain, as well as fast, accessible and reliable methods to detect potentially harmful resides and contaminants.
Taking the antibiotic, sulphonamides, as an example, the author explained how the use of veterinary drugs in the European Union is regulated by Council Regulation No. 2377/90, which describes the procedure for establishing a maximum residue level (MRL) for veterinary medicines in foods of animal origin, including poultrymeat, and succeeding regulations. A recent study established and then implemented an analytical method for the determination of sulphonamide residues in poultrymeat, important to minimise the risk of antibiotic resistance in humans. This uses High Performance Liquid Chromatography for the extraction step, followed by diode array detection (DAD) and/or fluorescence detection (FLD). DAD is fast and allows confirmation of the presence of the antibiotic but FLD can be used to quantify the level with some sensitivity, even below the MRL.
Coccidiosis vaccines can play a role in reducing residues in poultry products, according to Petr Bedrnìk of Biopharm (Research Institute of Biopharmacy and Veterinary Drugs) in the Czech Republic. Anticoccidial drugs, especially the ionophores, can have adverse side-effects in other farm animals, particularly ruminants and horses. Although health issues in humans have not been reported, the risks for other animals are being reduced as coccidiosis vaccines are becoming more widely used and accepted around the world.
Several well publicised cases of dioxins and similar compounds entering the food chain in recent years have focused attention on their levels in poultrymeat and other foods of animal origin. New MRLs for dioxins and dioxin-like polychlorinated biphenyls (PCBs) came into force for poultry products (and other foods of animal origin) in the European Union in November 2006. This is based on the sum of dioxins, furans and dioxin-like PCBs in animal fats. The European Commission also set a maximum level for the sum of six marker PCBs in fat.
Because there was a dearth of data, the German government funded a project at the Federal Research Centre for Nutrition and Food into the levels on these toxins in feed and animal products. Dr Wolfgang Jira reported the results of 200 samples of animal feeds and a selection of the 300 samples of animal products examined. Average values for 35 chicken meat samples and 14 turkey samples were well below the action levels.
The authors also presented a poster on their findings on the levels of the same toxins in animal feeds in Germany. Here too, they found the levels of dioxins and dioxin-like PCBs significantly below the action levels.
M. Gensler from the same research institute reported studies on the levels of polybrominated diphenylether (PBDE) in poultrymeat and eggs. PDBEs are flame retardants widely used in the manufacture of consumer goods. They find their way into the environment and thus, into the food chain but unlike PCBs and dioxins, the levels of PBDEs are still rising. PDBE concentrations found varied between samples of chicken meat, ranging from 0.02 to 1.1mcg/g fat useful data to track how these levels change over coming years.
Zoonoses and poultrymeat
As an introduction to this topic, Nico Bolder of Wageningen UR in the Netherlands outlined the effect of EU zoonosis and related legislation on the European poultry industry. Amid a rising tide of legislation, he described the latest directives and regulations, particularly as they apply to food safety issues, supporting the need for legislation to protect consumer health. Micro-organisms with potential public health priorities listed in EU Directive 2003/99/EEC include salmonella, campylobacter and Listeria monocytogenes, all of which are associated with poultrymeat and poultry products. This was followed up by Regulation 2160/2003, which had the primary aim to reduce the occurrence of Salmonella spp. in foods from poultry and pigs.
Dr Bolder went on to describe the various regulations and directives covering antibiotic growth promoters in feed, feedstuff microbiology, safe machinery, avian influenza and welfare.
EU legislation related to food safety, which is part of General Food Law, is very complex and constantly changing. The Zoonosis Directive is already in force but detail is still being added to framework legislation on salmonella reduction. European Food Safety Authority (EFSA) is working on establishing baseline studies in member states, from which targets for controlling salmonella will be set. Legislation has been completed on the use of antibiotics and vaccines to control salmonella in poultry, and guidelines on carcass decontamination are expected soon.
Baseline listeria levels
One of the possible sources of poultry product contamination is the production unit. Among the first steps in controlling the levels of zoonoses in food products is to establish the baseline levels on farms and in processing plants, and several presenters reported their findings at the conference.
M. Chemaly, for example, reported on the prevalence of Listeria monocytogenes in broiler flocks all over France, observing 15% positive samples and 32% positive flocks. The figures were numerically higher for the free-range flocks than those reared indoors.
Campylobacter studies on farm
Food-borne disease still makes the headlines in the media across the world from time to time. Although much work has been done to minimise the risks, salmonella and campylobacter infections among others continue to cause ill-health in consumers and in some cases, serious long-term effects and even death.
H. Bunkenborg (Danish Meat Association) reported on success in significantly reducing the incidence of campylobacter contamination by eliminating flies from poultry houses. This was achieved by setting up nets over access doors and fan inlets. The method was unpopular with farmers, however, because the nets required frequent cleaning to remove dust, adding to the farm work-load. Had a premium been offered for campylobacter-free broilers, the farmers may have reconsidered this option more favourably. Although flies are not the only source of campylobacter infection, the same researchers noted from earlier work that the sub-types found in sheep, flies and chickens bore the same DNA, implying that flies may have played a role in the transfer of infection.
...and at the processing plant
Ewa Pacholewicz from Poland's August Cieszkowski Agricultural University reviewed campylobacter contamination at the processing plant. Starting on 14 Dutch farms that were confirmed as campylobacter-positive from faecal samples, the researchers took samples at six stages along the slaughter line. On average, 94.2% of samples were positive. Campylobacter counts on skinless product tended to be lower than the meat with skin, confirming previous studies. Although the graph shows that campylobacter concentrations declined during processing, final product levels were still sufficient to present an infection threat to consumers. As a result, the authors concluded that external interventions are required to reduce the risks to those handling poultrymeat.
Dr John Cason from USDA's Russell Research Institute presented his computer calculation on bacterial survival during scalding in the processing plant. His model variables were the number of scalder tanks, presence or otherwise of counter-flow, over-flow and two levels of bacterial mortality (one-log reduction in 10 minutes versus zero mortality). The model indicated that the number of bacteria on scalded carcasses can be lowered by increasing bacterial mortality and/or reducing the amount of water carried by the wet carcasses.
Lessons from risk analysis
What are the risks of campylobacter in the population and how can they be minimised? From the Institute for Agricultural and Fisheries Research (ILVO) in Melle, Dr W. Messens presented a quantitative risk assessment of human campylobacteriosis through the consumption of chicken meat in Belgium.
Strategies to reduce campylobacter shedding were the most effective measures at the farm level. Reducing flock prevalence by 75% admittedly a demanding target cuts the number of cases of human campylobacteriosis to the same degree as a reduction in campylobacter shedding of 1.7-log. At the processing plant, the most effective treatment would be irradiation although that may not be acceptable to consumers. Spraying carcasses with electrolysed and oxidised water would lead to a reduction in cases of 80%. A lactic acid spray would reduce cases by 38%, and crust freezing by 61%.