Usefulness of Escherichia coli and Enterobacteriaceae as Process Hygiene Criteria in poultry: experimental study

Abstract

An experimental study in seven poultry slaughterhouses located in the EU was carried out with the objectives i) to collect relevant data on the variability of the counts of E. coli and Enterobacteriaceae on broiler carcasses sampled post evisceration and post chilling; ii) to collect information about the slaughterhouses visited and the sampled batches to explain the variability of the counts; iii) to compare E. coli and Enterobacteriaceae counts on the carcasses with their categorization in terms of levels of visual faecal contamination. The study quantified the level of E. coli and Enterobacteriaceae in 3 777 samples of neck skin, 1 887 obtained from carcasses at post evisceration and 1 890 at post chilling. In total, 97 out of the 3 777 broiler carcasses were classified as dirty in terms of levels of visual faecal contamination. The data collected were statistically analysed to assess the effect of slaughterhouse, batch and carcass variables on bacterial counts using a multilevel mixed linear model for hierarchical data. It was demonstrated that bacterial loads of both indicators were generally significantly lower at post chilling compared to post evisceration, and depended on the broiler's weight category. At post evisceration inspection, the inspector has the potential to visually classify carcasses as dirty; however, the probability of failure to recognise those carcasses with high bacterial counts is very high. The variables at batch and slaughterhouse level which affected the bacterial counts on carcasses were: weight category of the broilers (both the bacteria and sampling points), presence of discarded animals (both the bacteria at the post chilling), presence of intestinal ruptures (E. coli at post evisceration) and plucking method (both the bacteria at post evisceration).