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United States Department of Agriculture

Agricultural Research Service

Title: Recovery of salmonellae following pH adjusted pre-enrichment of broiler carcasses treated with trisodium phosphate

Authors
item Bourassa, Dianna
item Fletcher, D - UGA
item Buhr, Richard
item Cason Jr, John
item Berrang, Mark

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 2, 2004
Publication Date: March 1, 2005
Citation: Bourassa, D.V., Fletcher, D.L., Buhr, R.J., Cason Jr, J.A., Berrang, M.E. 2005. Recovery of salmonellae following pH adjusted pre-enrichment of broiler carcasses treated with trisodium phosphate. Poultry Science. 83(3):475-478.

Interpretive Summary: Trisodium phosphate (TSP) has been reported to reduce salmonellae on poultry carcasses. It has been suggested that the high pH and the detergent-like properties of TSP solutions are responsible for this reduction. An experiment was conducted to determine if controlling pH (alkaline 8.5 or neutral 7.2) during sampling for salmonellae changes the effectiveness of TSP. Carcasses were obtained from a commercial processing plant just prior to TSP application. Carcasses were subjected to one of four treatment groups; 1) TSP and alkaline sampling, 2) TSP and neutral sampling, 3) non-TSP and alkaline sampling, 4) non-TSP and neutral sampling. Each carcass was placed into a plastic bag with 500 mL of pH adjusted buffered peptone, the carcasses shaken for 1 min, and pre-incubation pH measured. Carcasses were incubated in the rinse at 37 C for 24 h and incidence of salmonellae was determined. The pre-enrichment pH for the TSP alkaline and the non-TSP alkaline groups was 8.5, and the pH for the TSP neutral and non-TSP neutral groups was 7.2. Salmonellae were detected from 40% of the TSP alkaline carcasses, 44% of the TSP neutral carcasses, 54% of the non-TSP alkaline carcasses, and 38% of the non-TSP neutral carcasses. Neither TSP treatment nor pH adjustment significantly influenced carcass salmonellae detection. Therefore, neither the high pH of TSP nor residual high pH during sampling affected salmonellae. The lack of salmonellae reduction between the TSP-treated and non-TSP treated carcasses may have been due to the minimal time of the pH shock, a lack of an immersion chilling step, or the high sensitivity of the method of salmonella recovery.

Technical Abstract: Trisodium phosphate (TSP) has been reported to reduce the recovery of salmonellae from processed poultry carcasses. It has been suggested that the high pH and the detergent-like properties of TSP solutions are responsible for the reduction in salmonellae recovery. This project was conducted to determine if controlling pH during salmonellae pre-enrichment changes the efficacy of TSP. Carcasses were obtained from a commercial processing plant immediately after the final inside-outside carcass washer, prior to any other microbial treatments, and before chilling. Carcasses were subjected to one of four treatment groups; 1) TSP and alkaline pre-enrichment, 2) TSP and neutral pre-enrichment, 3) non-TSP and alkaline pre-enrichment, 4) non-TSP and neutral pre-enrichment. Carcasses were individually placed into plastic bags, 500 mL of pH adjusted buffered peptone was added, the carcasses shaken for 1 min, and pre-incubation pH measured. Carcasses were incubated in the rinse at 37 C for 24 h and incidence of salmonellae was determined. The pH of the pre-incubation broth was 8.4 for the TSP alkaline pre-enrichment, 7.2 for the TSP neutral pre-enrichment, 8.6 for the non-TSP alkaline pre-enrichment, and 7.1 for the non-TSP neutral pre-enrichment. Salmonellae were detected from 40% of the TSP alkaline pre-enrichment carcasses, 44% of the TSP neutral pre-enrichment carcasses, 54% of the non-TSP alkaline pre-enrichment carcasses, and 38% of the non-TSP neutral pre-enrichment carcasses. Neither TSP treatment nor pre-enrichment pH adjustment significantly influenced carcass salmonellae detection.

Last Modified: 12/18/2014