The effectiveness of slurry ice for reducing Campylobacter on free-range poultry carcasses

Campylobacter, a leading cause of foodborne illnesses in the EU, presents significant challenges in free-range broilers due to their limited biosecurity and increased environmental exposure. IceGun® is a device designed to spray slurry ice on poultry carcasses to enhance chilling, and its effectiveness in reducing Campylobacter was evaluated in a Danish slaughterhouse specialising in free-range broilers. In each of four trials, forty carcasses from a Campylobacter-positive flock were randomly selected, and half were subjected to air chilling and slurry ice treatment, while the other half received only air chilling. Neck and leg skin samples were collected after chilling and analysed for Campylobacter. Selected Campylobacter isolates (n = 90) were whole-genome sequenced to assess genetic diversity. Additionally, the carcasses were packaged in modified atmosphere packaging (MAP), refrigerated over the shelf life period, and analysed for microbiological, chemical, and sensory parameters. Of the four flocks tested, slurry ice application significantly reduced Campylobacter concentrations on neck skin by 0.44 log₁₀ CFU/g, while effects on leg skin were less pronounced. Slurry ice treatment accelerated chilling without affecting product quality during the shelf life period under MAP and refrigeration. Genomic analyses revealed substantial genetic diversity among the isolates, with nine predominant sequence types (STs), including ST-52, associated with human infections. Some STs were present beyond the defined shelf life, suggesting resilience under refrigeration and MAP. Antibiotic resistance profiling showed a low prevalence of resistance genes among the isolates. The study highlights the dual benefits of slurry ice technology in improving food safety without compromising product quality in free-range broiler processing.