When it comes to food safety, poultry-associated illness – usually as the result of contamination by Campylobacter jejuni – is common and largely preventable. Biosecurity efforts aimed at broiler farms and processing facilities have shown limited effectiveness. Flock infection occurs very early in the life cycle (3-4 weeks old), and cross-contamination during processing is almost unavoidable. This means that a high percentage of poultry carcasses leave processing positive for Campylobacter. For this reason, it is imperative to target the food safety focus on the food preparation environment.
Since poultry-borne bacteria readily transfer from raw chicken to other food products via food preparation equipment and the operator’s hands, basic knowledge of food safety and good hygiene practices can mitigate this threat. Further, control technologies, including cook-in-the-bag and freezing, may offer consumers effective tools to prevent cross-contamination in the domestic kitchen. In a recent study, Bolton et al.1 evaluated both of these control technologies for efficacy against bacterial contamination.
The team used Pseudomonas fluorescens, plated on Pseudomonas agar with Pseudomonas CFC selective supplement (Thermo Scientific), to demonstrate the ready spread of bacteria from poultry to primary (hands, chopping boards, knives, plates) and secondary (dishcloth, fridge microwave, press/oven handles, tinfoil, microwave buttons, draining board) contamination sites. Bacterial counts at the primary sites were considerably higher (2.76 to 5.24 log10 CFU/cm2) than those at the secondary sites (0.28 to 1.54 log10 CFU/cm2). They further found that cleaning these sites with warm soapy water positively impacted detectable incidence and contamination levels but did not completely remove the bacteria from certain surfaces, notably the chopping board, knife handle, dishcloth, and draining board. When the team applied the cook-in-the-bag method, they only detected P. fluorescens on the defrosting plate (0.91 log10 CFU/cm2).
The researchers also inoculated poultry samples with Campylobacter, using three strains of C. jejuni and two strains of C. coli, and subjected them to freezing (−20°C). They observed a significant decrease in bacterial counts from the initial count (5.34 log10 CFU/g) to the count one week post-freezing (3.61 log10 CFU/g). These counts continued to decrease over a total of six weeks with a final bacterial count of 1.88 log10 CFU/g. The team asserts that, while this control technology did not completely eliminate Campylobacter, the reduced bacterial counts significantly decreased consumer risk.
Sensory analysis revealed differences between consumer response to frozen chicken fillets versus fresh controls. In general, frozen samples received worse ratings for appearance (higher “shine”) and texture (more “firm and “dry” and less “moist”). On the other hand, the researchers report no change in the flavor of the frozen chicken samples.
Overall, Bolton et al. demonstrated how readily bacteria transfer from contaminated poultry to hands and food preparation surfaces. They found that one control technology, cook-in-the-bag, significantly reduced cross-contamination. The second control technology, freezing, significantly decreased Campylobacter counts over time. These technologies, combined with consumer education on effective hygiene in the domestic kitchen, could significantly reduce consumer risk for poultry-associated illness, particularly with further enhancement to improve the reception of frozen food products.
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1 Bolton, D. et al. (2014) ‘Poultry Food Safety Control Interventions in the Domestic Kitchen.’ Journal of Food Safety 34:1, 34-41, DOI: 10.1111/jfs.12092