1. Propidium monoazide (PMA) qPCR assay compared to the plate count method for quantifying the growth of Salmonella enterica serotypes in vacuum-packaged turkey breast combined with a mathematical modeling approach.
- Author
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Sousa Severo D, Martins WF, Miotto M, Verruck S, Rodrigues de Oliveira R, and Aragão GMF
- Subjects
- Animals, Vacuum, Colony Count, Microbial methods, Food Packaging methods, Serogroup, Models, Theoretical, Food Microbiology methods, Temperature, Food Contamination analysis, Salmonella enterica growth & development, Salmonella enterica genetics, Salmonella enterica isolation & purification, Turkeys microbiology, Azides chemistry, Propidium analogs & derivatives, Propidium chemistry, Propidium pharmacology, Real-Time Polymerase Chain Reaction methods
- Abstract
This study compares the plate count (PC) and the Propidium Monoazide-quantitative Polymerase Chain Reaction (PMA-qPCR) methods to assess the growth of a cocktail of three serotypes of Salmonella enterica (Heidelberg, Typhimurium, and Enteritidis) in cooked, sliced, and vacuum-packaged turkey breast (STB) under isothermal storage temperatures (8 °C-20 °C), using predictive models. Standard curves were developed for PMA-qPCR, demonstrating high efficiency (101%) and sensitivity, with quantification limits ranging from 1 to 2 log
10 CFU/g for all temperatures studied. Comparative analysis revealed a significant correlation (R2 = 0.99; 95% CI) between the PC and PMA-qPCR methods; however, the agreement analysis indicated a mean difference (Bias) of -0.11 log10 CFU/g (p < 0.05), suggesting underestimation by the PC method. This indicates the presence of stressed or viable but nonculturable (VBNC) cells, detectable by PMA-qPCR but not by PC. The Baranyi and Roberts model showed a good ability to describe the behavior of S. enterica cocktail in STB for PC and PMA-qPCR data under all isothermal conditions. The exponential secondary model more accurately represented the temperature dependence of the maximum specific growth rate compared to the Ratkowsky square root model, with R2 values ≥ 0.984 and RMSE values ≤ 0.011 for both methods. These results suggest that combining PMA-qPCR with predictive modeling allows for a more accurate prediction of S. enterica growth, compared to PC method. In the event of cold chain disruptions of meat products, the use of PMA-qPCR method allow the quantification of VBNC cells, that can still pose a health risk to consumers, especially in ready-to-eat products., Competing Interests: Declaration of competing interest The authors declare that they have no financial or non-financial interests that could be perceived as potential conflicts of interest regarding this research. None of the authors have received any form of compensation, including honoraria or consultancy fees, from any organization that may gain or lose financially from the publication of this manuscript. The authors have no financial or personal relationships that could bias this work or create a potential conflict of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2025
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