Reducing Campylobacter jejuni, Enterobacteriaceae, Escherichia coli, and total aerobic bacteria on broiler carcasses using combined ultrasound and steam

Campylobacteriosis is the most frequently reported foodborne illness in Europe and many other parts of the world. Campylobacter can colonize the intestines of broilers, most often in large amounts. Broilers are usually slaughtered in a high-speed automated system that can rupture the intestines during evisceration, resulting in contamination of carcasses with intestinal bacteria such as Campylobacter. This study evaluated the combined effect of ultrasound and steam (SonoSteam®) on naturally contaminated chicken carcasses at a large-scale abattoir in Sweden. Ultrasound at 30-40 kHz and steam at 84-85 °C or 87-88 °C was used at slaughter with a line speed of 18 000 birds per hour. The amount of Campylobacter spp., Enterobacteriaceae , Escherichia coli , and total aerobic bacteria on neck skins from 103 chicken carcasses, sampled before and after treatment by SonoSteam, was analyzed.Campylobacter spp. was detected in 58 (56%) of the 103 neck skins, from birds belonging to four of the seven flocks represented. All 58 isolates were identified as Campylobacter jejuni . After the SonoSteam treatment, a mean reduction in C. jejuni, Enterobacteriaceae, E. coli and total aerobic bacteria were log 0.5 ± 0.8, log 0.6 ± 0.6, log 0.5 ± 0.6, log 0.4 ± 0.7 CFU/g respectively. No significant differences in reduction between the two different treatment temperatures was observed for any of the bacteria.Although the bacterial reductions were significant, large amounts of bacteria remained on the carcasses after treatment. Further studies are needed to identify optimal measures at slaughter to reduce food spoilage bacteria and pathogenic bacteria, which should be considered in a One Health perspective.