Differences in antimicrobial activity of chlorine against twelve most prevalent poultry-associated Salmonella serotypes

Chlorine is the most widely used carcass sanitizer in poultry processing in the USA. The objective of this study was to determine the effects of varying concentrations of organic matter on the susceptibility of twelve most prevalent poultry-associated Salmonella serotypes (MPPSTs) to chlorine. To mimic the microenvironment of the water used for immersion chilling, we manipulated organic matter contamination levels in pre-chilled (pH∼6, T∼4 °C) chlorinated (50 ppm) water using varying concentrations (0, 1, 2, 3, 4, and 5%) of chicken-meat-extract (CME) produced from frozen chicken carcasses. This CME-based in vitro model was challenged with ∼1 × 105 CFUs of each MPPST isolate and the bacterial survival was tested at 5, 30, 60 and 90 min post-challenge. In this model, the decimal reduction time (D90-values) of each MPPST was linearly correlated with the concentration of CME. Significant inter-serotype differences in the D90-values were observed. The results show that the pH, concentration of total- and free-chlorine were also linearly correlated with the presence of CME in a concentration-dependent manner. The findings of this study indicate that the serotype and the levels of organic matter contamination significantly influence Salmonella survival and that both variables should be included in models that predict effectiveness of chlorine treatment in immersion chilling.