Identification of chicken component samples containing Salmonella concentrations greater than or equal to 1 CFU/g

Authors: Schmidt, John; WU, WEIFAN - Oak Ridge Institute For Science And Education (ORISE); Harhay, Dayna; Wheeler, Tommy

Submitted to: Meat and Muscle Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2025
Publication Date: 5/7/2025
Citation: Schmidt, J.W., Wu, W., Harhay, D.M., Wheeler, T.L. 2025. Identification of chicken component samples containing Salmonella concentrations greater than or equal to 1 CFU/g. Meat and Muscle Biology. 9(1). Article 18993. https://doi.org/10.22175/mmb.18993.
DOI: https://doi.org/10.22175/mmb.18993

Interpretive Summary: United States Department of Agriculture - Food Safety and Inspection Service will soon regulate Salmonella levels in the chicken portion of not ready-to-eat breaded stuffed chicken products. We developed and tested two protocols for this soon to be regulatory Salmonella threshold. One protocol used a single sample. The other protocol used three replicate samples with goal of reducing the number of false positive test outcomes. Both tests detected 100% of chicken samples with Salmonella levels above the regulatory Salmonella threshold. The protocol using three replicate samples reduced false positive test outcomes. These threshold protocols provide a better combination of cost, speed, ease of use, and accuracy than currently available Salmonella quantification methods for the chicken portion of not ready-to-eat breaded stuffed chicken products.

Technical Abstract: Ongoing discussions regarding new strategies to enhance control of Salmonella in meat and poultry include the potential benefits of identifying product that exceeds various Salmonella levels. A method known as “Poisson Limit One Tube” (PiLOT) produces a positive result when a sample exceeds a threshold level of bacterial contamination. The Poisson probability distribution is the mathematical foundation of the PiLOT method. Thus, a PiLOT method protocol (PiLOT-95) with a 95% probability of a positive result when a chicken sample contains 1 CFU/g of Salmonella has a 50% probability of a positive result when a sample contains 0.2 CFU/g of Salmonella. The “Confidently Above Threshold” (CAT) method was developed to reduce the potential for false positive results. A CAT method protocol (CAT-80) with an 80% probability of a positive result when a chicken sample contains 1 CFU/g of Salmonella has a 50% probability of a positive result when a sample contains 0.6 CFU/g of Salmonella. Eighty samples of the chicken component of not ready-to-eat (NRTE) breaded stuffed chicken products were prepared by inoculating with Salmonella levels between <0.1 to 52.5 CFU/g. Each of the samples was assessed for the presence of Salmonella levels >/=l.0 CFU/g with PiLOT-95 and CAT-80 protocols. For both PiLOT-95 and CAT-80, Sensitivity was 1.000 because no false negative results occurred. This result demonstrated the validity and feasibility of threshold methods for Salmonella in NRTE breaded stuffed chicken products. The CAT-80 false positive rate (FPR) of 0.225 was lower than the PiLOT-95 FPR of 0.500. PiLOT-95 and CAT-80 Specificities were 0.500 and 0.775, respectively. These results demonstrated that the CAT-80 protocol reduces the occurrence of false positive outcomes compared to the PiLOT-95 threshold protocol. CAT methods may provide an optimal approach for detecting chicken component samples with greater than or equal to 1 CFU/g Salmonella.