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Title: Control of salmonella at the chill tank

item Berrang, Mark

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/12/2011
Publication Date: 10/12/2011
Citation: Berrang, M.E. 2011. Control of salmonella at the chill tank. National Meeting on Poultry Health and Processing sponsored by Delmarva Poultry Industry, Inc. October 12-13,2011. Ocean City, Maryland.

Interpretive Summary:

Technical Abstract: Control of Salmonella on poultry meat should be in the form of a continuous effort from the breeder farm to the fully processed and further processed product, as well as, consumer education. However, control is often measured at the chill tank and efforts are made to relate prevalence to processing parameters. We have studied processing methodologies applied at commercial broiler plants and measured the affect on Salmonella prevalence. We tested the use of a scald water additive to increase the pH from near neutral to 9.89 in an attempt to lessen Salmonella contamination before feather removal. Carcasses subjected to the high pH scald were numerically but not significantly less likely to be contaminated with Salmonella than those treated by standard scald. After proceeding through commercial automated defeathering which increased Salmonella prevalence, a subsequent chlorine dip tank was found to be ineffective to lessen Salmonella prevalence on carcasses previously treated with a high pH scald. Moderating the increased microbial contamination during defeathering has been the goal of multiple research projects. One such project was conducted in a commercial plant and involved application of chorine dioxide through existing plumbing in feather picking machines. Carcasses subjected to standard feather picking with a water spray suffered a significant increase in Salmonella prevalence. Carcasses defeathered under a spray of 50 ppm chlorine dioxide did not have a co-incident increase in Salmonella contamination. Broiler processors also employ various spray and brush washers on both the kill and evisceration lines. We examined the efficacy of multiple wash steps in a commercial broiler slaughter plant. When examined individually, no single spray or brush washer had a significant affect on prevalence of Salmonella. However, overall processing resulted in a dramatic decrease in prevalence from approximately 80% pre-scald to approximately 25% pre-chill. Finally chemical processing aids are approved for use in commercial broiler processing to lessen microbial contamination. We conducted a 1 year study in 20 randomly selected large commercial broiler processing plants, using different combinations of processing aids, to determine Salmonella prevalence at re-hang and post chill. We found 8 different types of processing aids (including none) being employed in on-line reprocessing. Some plants were also applying chlorine in washers and chill tanks. Salmonella prevalence ranged from 32 to 97% at re-hang and from 2 to 60% post-chill. Regardless of chlorine use, or type of chemical aid, broiler processing significantly lessened Salmonella prevalence in all plants and all replications. We found that serotype of Salmonella detected had more to do with the incoming population than the antimicrobial chemicals used in processing. Overall, broiler processing is very effective to lessen microbial contamination of carcasses. Salmonella prevalence is reliably lessened to a significant degree through modern processing techniques. Further research and ongoing optimization of processing parameters will help processors as they continue to improve the microbiological quality of poultry meat products.