Regulator approves four antimicrobials for use with chicken

The decision is also one of the first applications of the bloc's new hygiene regulations in relation to removing contamination from meats.

EU regulation No 853/2004, part of the package of hygiene laws that came into effect on 1 January, provides a legal basis to permit the use of a substance other than potable water to remove surface contamination from products of animal origin. Previously, such a legal basis did not exist in the bloc's legislation for red meat and for poultry meat.

For many decades food regulators have been hesitant to endorse the use of antimicrobial substances by poultry processors. They have argued that processors would use antimicrobials to mask unhygienic slaughter or processing practices.

If permitted for use, it was also feared that their widespread use coupled with high bacterial counts due to unhygienic practices, would induce resistance of the micro flora present on the surface of the treated products.

The European Food Safety Authority's (EFSA) endorsement yesterday of trisodium phosphate, acidified sodium chlorite, chlorine dioxide or peroxyacid solutions to clean chicken carcasses marks a shift from that policy.

"With the adoption of the hygiene package and the introduction of the hazard analysis and critical control points (HACCP) principles in the entire food chain, establishments are obliged to improve their hygiene and processing procedures,"​ EFSA stated. "Under such circumstances the use of antimicrobial substances on food of animal origin can be reconsidered."​

The scientific opinion, issued by EFSA's panel on food additives, flavourings, processing aids and materials in contact with food (AFC), stated that the four antimicrobials pose no risk to human health.

Chicken is a major culprit behind Salmonella and Campylobacter food borne infections in the EU. EFSA's positive opinion widens the choice for food processors in what chemicals they can use when cleaning chicken carcasses. Antimicrobials are a class of substances that destroy or inhibit the growth of bacteria.

"On the basis of available data and taking into account that processing of poultry carcasses (washing, cooking) would take place before consumption, the panel considers that treatment with trisodium phosphate, acidified sodium chlorite, chlorine dioxide, or peroxyacid solutions, under the described conditions of use, would be of no safety concern,"​ EFSA stated.

The panel also noted that spraying poultry carcasses with antimicrobials, by comparison to dipping and immersion treatments, reduces the exposure to residues and by-products that might arise.

"The panel stresses that the use of antimicrobial solutions does not replace the need for good hygienic practices during processing of poultry carcasses, particularly during handling, and also stresses the need to replace regularly the water of chiller baths,"​ EFSA stated.

EFSA's decision follows an opinion issued in October 1998 by the EU's Scientific Committee on Veterinary Measures relating to Public Health (SCVPH).

SCVPH noted that antimicrobial substances should only be permitted for use in the EU if companies apply a fully integrated control programme throughout the entire food chain.

A second opinion by SCVPH in April 2003 on the evaluation of antimicrobial treatments for poultry carcasses concluded that decontamination can be a useful way of further reducing the number of pathogens in chicken carcasses. Both of SCVPH's opinions stressed that antimicrobial substances should be assessed thoroughly before their use is authorised.

As a first step to the authorisation of antimicrobial substances in the EU, the US submitted four technical dossiers asking EFSA to allow the use of the four antimicrobial substances for cleaning poultry carcasses. The submission was made under a recent veterinary accord between the EU and the US.

The way poultry carcasses get contaminated with harmful bacteria is very specific. First, there is retention of bacteria in a liquid film on the skin. Afterwards, bacteria are more closely associated with the skin, even untrapped in inaccessible sites.

Spray rinsing with antimicrobials at several points along the processing line is an effective means of minimising contamination but is not so effective especially in exposed areas of connective tissue that are more heavily contaminated, EFSA noted.

In general, the rinsing treatments are able to reduce the contamination level but do not completely eliminate pathogens. Their effectiveness depends on the initial microbial load and treatment conditions.

There are many factors affecting the efficacy of these antimicrobials, including the concentration of the substance, the time of exposure, temperature, pH and hardness of water, strength of bacterial adhesion to the carcasses, biofilm formation and the presence of fat or organic material in water.

The antimicrobial resistance is highly enhanced when bacteria are attached to a surface or form part of a biofilm. Legislation requires poultry carcasses to be cooled within defined limits before shipping.

The cooling is generally accomplished by immersing the carcasses in cold water in long flow-through tanks called chillers. During immersion chilled carcasses absorb water that can represent up to a eight per cent increase in weight depending upon the size of the carcass.

Since the water is not regularly renewed for economic reasons, treatment with antimicrobial agents can control microbial proliferation in the chillers baths.

EFSA noted that the proposed treatments of poultry carcasses with trisodium phosphate, acidified sodium chlorite, chlorine dioxide, peroxyacetic and peroxyoctanoic acids have been tested for the inactivation of bacterial, viral and protozoan pathogens found on poultry and in poultry processing plants.

US poultry processors use the chemicals either as spray or washes for on-line reprocessing. The chemicals can also be added to chiller baths to limit the potential for cross-contamination.

Trisodium phosphate is typically used at an eight per cent to 12 per cent mixture in aqueous solutions. The solution is kept at a temperature between 7ºC and 13ºC and applied by dipping or spraying the carcasses for up to 15 seconds.

Carcass exposure time is controlled by line speed and length of the application cabinet. Trisodium phosphate destroys pathogens and has a “detergent effect” that allows the removal of bacteria by the washing process.

Sodium chlorite, at a concentration of 500-1200 mg/L, is activated with any acid approved for use in foods at levels sufficient to provide solutions with pH values in the range 2.3-2.9 for either a 15 second spraying or 5-8 second dipping. In the case of immersion in chilling water, the concentration is up to 150 mg/L at pH between 2.8 and 3.2. Poultry carcasses are kept in the chiller for an hour but this can be as long as three hours.

The main active ingredient of acidified sodium chlorite (ACS) solution is chlorous acid, which is a very strong oxidizing agent. It is stronger than either chlorine dioxide or chlorine.

For use as an antimicrobial agent it is added to water in a concentration up to 50 mg/L in order to maintain a residual concentration of 2.5 mg/L. It can be used both in on-line reprocessing as a spray or wash or in chiller baths to limit the potential for microbial cross-contamination.

Peroxyacetic and peroxyoctanoic acids is usually added to a cleaning solution as a stabiliser. Acetic and octanoic acids are also present in the peroxyacids solution. Acetic acid acts as an acidifier and octanoic acid as a surfactant. A solution of the acids may be used both in on-line reprocessing during a 15 second spray down or wash.

It can be used for a 60 minute immersion in chiller baths to limit the potential for microbial cross contamination.