Microbiological and Hydraulic Evaluation of Immersion Chilling for Poultry

Immersion chilling has been identified as a critical control point in commercial poultry processing. A study was undertaken to investigate the impact of immersion chilling on the microbiology of carcasses within a small to medium sized commercial operation. Fifty chilled carcasses (following immersion chilling) sampled over a 10-day period using a whole bird rinse technique exhibited mean standard plate count (SPC) and coliform counts (log colony-forming units (CFU)/ml) of 3.74 and 3.03, respectively. These levels were both significantly (P < 0.005) lower (ca. 1 log unit) compared to similar numbers of prechill carcasses (birds exiting the inside-outside washer but prior to the prechiller). Water from the chiller was also shown to contain significantly (P < 0.005) lower (ca. 1 log unit) SPC and coliform levels compared to those from the prechiller. Reducing the flow of water at the inside-outside washer by 50% did not significantly (P < 0.001) affect the SPC and coliform levels of either prechilled or chilled carcasses.