Effects of Immersion Chilling Using Different Volumes of Water on Bacteria Recovery From Broiler Carcasses and Chiller Water

Authors: Northcutt, Julie; Smith, Douglas; Cason Jr, John; Buhr, Richard - Jeff; FLETCHER, DANIEL - UGA

Submitted to: U.S. Poultry and Egg
Publication Type: Abstract Only
Publication Acceptance Date: 1/13/2006
Publication Date: 1/21/2006
Citation: Northcutt, J.K., Smith, D.P., Cason Jr, J.A., Buhr, R.J., Fletcher, D.L. 2006. Effects of immersion chilling using different volumes of water on bacteria recovery from broiler carcasses and chiller water [abstract]. U.S. Poultry and Egg Association. 1:1.

Interpretive Summary:

Technical Abstract: During a previous experiment, we investigated the microbiological impact of using a low (2.1 L/kg) or a high volume (16.8 L/kg) of non-chlorinated water to immersion chill broiler carcasses. From that study, it was concluded that the low volume of water removed fewer total aerobic bacteria, E. coli, Enterobacteriaceae and Campylobacter from carcasses than the high volume of water. However, when chiller water was analyzed on a per mL basis, equivalent counts of bacteria were recovered regardless the volume. A subsequent study was designed to determine if there is an optimum volume of water between 2.1 and 16.8 L/kg for immersion chilling. Market-aged broilers (average live weight 2.5 kg) were processed using simulated commercial conditions (stunned, bled, scalded, picked, mechanical eviscerated). Immediately after the final bird washer, carcasses were cut into left and right halves, and each half was tagged and weighed. One half of each pair was chilled in a bag containing either 3.4 L/kg or 6.7 L/kg of distilled water (4°C), and these bags were then submersed in a secondary chill tank in 150 L of an ice-water mix (0.6°C). After chilling for 45 min, carcass halves were removed from the bags using clean sterile gloves, allowed to drip for 5 min, and subjected to a half carcass rinse in sterile water. Carcass rinses were analyzed for total aerobic bacteria, E. coli, Enterobacteriaceae and Campylobacter. Two extra carcasses per replication (6 total carcasses) were selected as prechill controls and were subjected a whole carcass rinse. Overall, immersion chilling reduced the level of total aerobic bacteria, E. coli, Enterobacteriaceae and Campylobacter recovered from carcasses rinses by 0.6 to 0.8 log10 CFU/mL. Counts of total aerobic bacteria, E. coli, Enterobacteriaceae and Campylobacter recovered from carcasses rinses were not statistically different for the chilling treatments (3.4 and 6.7 L/kg). Average counts of bacteria recovered from carcasses chilled with 3.4 L/kg were 3.9, 3.3, 3.6, and 2.4 log10 CFU/mL of total aerobic bacteria, E. coli, Enterobacteriaceae and Campylobacter, respectively. Similarly, average counts of bacteria recovered from carcasses chilled with 6.7 L/kg were 4.1, 3.3, 3.6, and 2.5 log10 CFU/mL of total aerobic bacteria, E. coli, Enterobacteriaceae and Campylobacter, respectively. The present study shows that increasing the volume of water from 3.4 to 6.7 L/kg will not remove more bacteria from broiler carcasses, and altering or monitoring chilling variables other than water volume (temperature, chlorine concentration, prechill carcass bacteria levels, etc.) may be more useful for reducing the level of bacteria remaining on chilled carcasses.