Chilling of poultry: the effects of process parameters on the level of bacteria in spin‐chiller waters

Abstract
Summary: A survey has been made of the effects of process parameters on the microbiological contamination of spin‐chiller waters at five poultry process plants in the UK. Water samples, taken at hourly intervals, from both the first and second chillers were examined bacteriologically and for the levels of residual chlorine pH value and turbidity. Water usage was also monitored. In one process line comparison was made of the effect of substantial modification to the process plant resulting in changes in both water usage and chlorination levels.The colony counts of presumptive coliform bacteria and other bacteria were reduced generally to < 11 and < 32 ml–1 respectively when high water usage (> 41/kg carcass weight) was combined with high total residual chlorine (30–50 ppm). Higher numbers of bacteria (normally < 105 ml–1) were recovered when high water usage (> 41/kg) was combined with low residual total chlorine (< 5 ppm) or when low water usage (< 1 1/kg) was combined with moderate levels of residual chlorine (7–16 ppm). The signifiance of the results is discussed with reference to the hygienic operation of spin‐chillers.