title: Thermal inactivation of Yersinia enterocolitica in pork slaughter plant scald tank water.
abstract: The objective of this study was to establish the time-temperature combinations required to ensure the thermal inactivation of Yersinia enterocolitica during scalding of pork carcasses. A 2 strain cocktail of Y. enterocolitica (bioserotypes 2/O:5,27 and 1A/O:6,30) was heat treated at 50, 55 and 60°C in samples of scald tank water obtained from a commercial pork slaughter plant. Samples were removed at regular intervals and surviving cells enumerated using (i) Cefsulodin-Irgasan-Novobiocin Agar (CIN) supplemented with ampicillin and arabinose and (ii) Tryptone Soya Agar (TSA), overlaid with CIN agar with ampicillin and arabinose. The data generated was used to estimate D- and z-values and the formula Dx=log(-1)(log D60-((t2-t1)/z)) was applied to calculate thermal death time-temperature combinations from 55 to 65°C. D50, D55 and D60-values of 45.9, 10.6 and 2.7min were calculated from the cell counts obtained on CIN agar, respectively. The corresponding D-values calculated from the TSA/CIN counts were 45.1, 11 and 2.5min, respectively. The z-value was 7.8. It was concluded that a time-temperature combination of 2.7min at 60°C is required to achieve a 1 log reduction in Y. enterocolitica in pork scald tank water. The predicted equivalent at 65°C was 0.6min. This study provides data and a model to enable pork processors to identify and apply parameters to limit the risk of carcass cross-contamination with Y. enterocolitica in pork carcass scald tanks.
authors.affiliation: Food Safety Department, Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland. declan.bolton@teagasc.ie
authors.forename: Declan J
authors.initials: DJ
authors.lastname: Bolton
authors.forename: Claire
authors.initials: C
authors.lastname: Ivory
authors.forename: David
authors.initials: D
authors.lastname: McDowell
mesh_terms: D000003:Abattoirs; D000818:Animals; D015169:Colony Count, Microbial; D059022:Food Safety / Q000379:methods*; D006358:Hot Temperature; D008460:Meat / Q000382:microbiology*; D013552:Swine; D014871:Water Microbiology; D015008:Yersinia enterocolitica
keywords: D-values; Meat food safety; Scald tank water; Yersinia enterocolitica