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Tackling Campylobacter in Poultry Plants

01 June 2014

With concerns rising over Campylobacter infections from poultry, treatments are being sought in the processing plant and on the farm to reduce the threat, writes Chris Harris.

There is substantial evidence to show that strains associated with chicken are a major source of disease, thought to be because chickens have high levels of Campylobacter contamination on the farm, which is maintained through processing to retail.

Around the world, food safety authorities and research departments are mounting a concerted effort to find ways of reducing the potential threat to human health both by controlling the pathogen on the farm before slaughter and in the processing plant to help reduce contamination on the processing line.

A recent study by the Centers for Disease Control and Prevention in the US found that workers in the processing plants were at risk of infection, particularly new workers who had been at the plant for less than a month and were working as hangers at the start of processing.

In the US, Campylobacter infection, or campylobacteriosis, affects an estimated 2.4 million people each year. In the UK, there is a similar prevalence of infections with about 460,000 cases of food poisoning, 22,000 hospitalisations and 110 deaths each year and a significant proportion of these cases come from poultry. The pattern of infections is repeated in virtually every country around the world.

The food safety authorities around the world have established their own protocols for reducing incidence of contamination within the processing plant and many have laid down limits for pathogen counts including Salmonella and Campylobacter.

In the US, current USDA FSIS regulations require processing companies not to exceed established low limits of Salmonella and Campylobacter in processed products, as monitored by testing programmes.

A number of methods including chemical interventions are used to control these pathogens in the plants.

Similar measures are applied in Europe and a recent study by the European Food Safety Authority (EFSA) found that solutions, containing peroxyacetic acid (PAA) as an active ingredient, in mixtures with acetic acid, hydrogen peroxide, and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and possibly octanoic acid and peroxyoctanoic acid were effective in reducing pathogens on poultry carcasses and meat.

The tests were carried out by the EFSA scientists after the USDA had submitted a dossier for approval to the European Commission for peroxyacetic acid solutions to be used by food business operators during processing for the reduction of pathogens on poultry carcasses and meat.

The USDA was seeking approval for PAA being used 1) on warm eviscerated carcasses or parts (pre-chill); (2) on carcasses in chiller baths (chill); (3) on chilled carcasses or parts (post-chill).

PAA can be applied as spray washing or dipping depending on the step in the processing line, however, the concentration of the active ingredient cannot exceed 2,000ppm in the short term baths for three minutes, and up to 230ppm in the long duration chiller baths, where the duration of exposure during chilling can be one to two hours.

The concentration in spray washes is typically 400 to 700ppm, applied for 10 seconds.

The maximum temperature is ambient temperature and pH of a 600ppm solution is approximately 2.5.

It is not intended to subsequently remove the PAA solution from the poultry carcasses or poultry meat.

PAA is highly reactive and, when used in the presence of organic compounds, dissociates very rapidly and loses antimicrobial properties.

PAA breaks down to acetic acid and water and the mixtures are not recycled.

The EFSA study found that there were no toxicity concerns with regard to residues when PAA was used in short term baths because of the high instability of the solution and there are no concerns over residues of acetic acid and octanoic acid,

The Authority also had no safety concern over the stabiliser HEDP with regard to the high concentration bath since for HEDP, a margin of safety ranging from 3,420 to 43,103 can be calculated against a No Observed Adverse Effect Level (NOAEL) of 50mg per kg bodyweight per day.

EFSA also said that there were no safety concerns over the products of hydrogen peroxide and peroxyacids with lipids and proteins/amino acids of the poultry carcasses. It was concluded that no risk was expected because of the low amino acid content in the carcass surface, including the short-term treatment at higher peroxide concentrations.

The EFSA study said there was consistent evidence for a relevant impact (1 to 3 log-units over untreated controls) of PAA treatment on E. coli and coliforms when treating warm carcasses by dipping.

There were few data on reduction of pathogens for this treatment.

Spraying of warm carcasses was less effective in reducing pathogens than dipping.

There was also evidence for a reduction of indicator organisms and pathogens when treating chilled carcasses or parts by dipping.

When adding PAA to chiller baths, a relevant impact of PAA treatment on E. coli (0.5 to 2 log-units) was registered, whereas the effects on coliform bacteria were less consistent.

EFSA said that there was few concerns about the contamination of waste water with the acetic acid residues but it did raise concerns about the effect that the emission of HEDP from a poultry plant including via a waste water treatment system into the fresh water environment.

EFSA said that there should be HACCP plans including:

  1. monitoring of the concentration of HEDP in the working PAA solution in order to control residues of HEDP on poultry carcasses (a method for the determination of HEDP residues on poultry carcasses should be developed and validated)
  2. monitoring of the concentration of the decontaminating substance in the working PAA solution, and
  3. post-marketing surveillance for resistance in both pathogenic and commensal bacteria if PAA is applied for decontamination of poultry carcasses.

However, while interventions in the processing plant - including the imposition of strict HACCP regimes and the use of various sprays to decontaminate the carcasses - can be effective in reducing pathogen counts, the more that can be done to reduce contamination of the carcasses before they enter the meat plant, the easier it is for the processor to control the situation.

In the US, for instance, a recent study in the turkey sector funded by the US Poultry and Egg Association found that wild strains of Campylobacter could be transferred through semen into the reproductive tracts of turkey breeder hens, representing a potential route for the transmission of the pathogen to progeny.

The study by Dr Jesse Grimes, Dr Sophia Kathariou, and Maria Crespo Rodriguez from North Carolina State University found that pests in the turkey house played a significant role in the spread of both Campylobacter and Salmonella.

In the UK, investigations have been carried out to determine the entire genetic code (genome) of Campylobacter strains from key stages through poultry processing and human disease. This genetic information will be used to examine how variation in the physical traits (phenotype), are determined by changes to the genes (genotype).

By considering the elimination of Campylobacter on the farm, the project aims to develop interventions that are effective and practicable for the poultry industry to use. To achieve this, state-of-the-art means of determining the entire genetic code of Campylobacter strains - from key stages through poultry processing and human disease – is to be used.

This systems approach to understanding Campylobacter survival and spread is hoped to inform targeted interventions.

The results of the investigation are expected shortly.

June 2014

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