Computer calculation of bacterial survival during industrial poultry scalding

Authors: Cason Jr, John

Submitted to: European Symposium on Quality of Poultry Meat
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2007
Publication Date: 9/2/2007
Citation: Cason Jr, J.A. 2007. Computer calculation of bacterial survival during industrial poultry scalding. Proceedings, 18th European Symposium on Quality of Poultry Meat. p. 130.

Interpretive Summary:

Technical Abstract: Computer simulation was used to model survival of bacteria during poultry scalding under common industrial conditions. Bacterial survival was calculated in a single-tank single-pass scalder with and without counterflow water movement, in a single-tank two-pass scalder, and in a three-tank two-pass counterflow scalder for bacteria suspended at different locations in the tanks. Within each design, common operating conditions were compared combining two scald water overflow conditions (825 ml or 0) and two mortality levels (a one log reduction in bacterial numbers in 10 minutes or no mortality). Calculations were based on uniform mixing within and between small volumes of water equivalent to the amount of total water per carcass, with recalculation for that volume for every carcass in the tank as each new carcass entered the tank. Simulations indicated that all of the major predictions of the Veerkamp scald model were confirmed even though the present model calculated mixing of water by a different method. Mortality of bacteria had a bigger impact than scalder design on numbers of bacteria that survived scalding and were carried out of the tank on wet carcasses, emphasizing the importance of factors that affect bacterial survival. Counterflow water movement reduced the numbers of bacteria exiting the scalder on wet carcasses, but the counterflow effect was of much less importance than mortality. Survival of bacteria suspended in scald tank water was related to the starting distance from the exit point for carcasses. Addition of overflow rather than replacement amounts of water had only a minor effect on the numbers of bacteria on carcasses exiting the scalders. Increasing scald tank volume had only a minor effect. Numbers of bacteria on scalded carcasses can be lowered by increasing bacterial mortality and reducing the volume of water carried by wet carcasses.