Department of Chemical Engineering and Food Engineering, Federal University of Santa Catarina, 88040-970, Florianópolis, SC, Brazil.
Department of Food Technology, Goiano Federal Institute of Education, Science, and Technology, Morrinhos Campus, 75650-000, Morrinhos, GO, Brazil.
Food Microbiol. 2025 Jan;125:104650. doi: 10.1016/j.fm.2024.104650. Epub 2024 Sep 29.
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 CFU/g for all temperatures studied. Comparative analysis revealed a significant correlation (R = 0.99; 95% CI) between the PC and PMA-qPCR methods; however, the agreement analysis indicated a mean difference (Bias) of -0.11 log 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 R 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.
本研究比较了平板计数（PC）和吖啶橙单栓定量聚合酶链反应（PMA-qPCR）方法，以使用预测模型评估在等温储存温度（8°C-20°C）下，三种血清型鼠伤寒沙门氏菌（海德堡、肠炎和肠炎）鸡尾酒在煮、切片和真空包装火鸡胸肉（STB）中的生长情况。为 PMA-qPCR 建立了标准曲线，证明其效率高（101%）且灵敏度高，所有研究温度下的定量极限范围为 1 至 2 对数 CFU/g。比较分析表明 PC 和 PMA-qPCR 方法之间存在显著相关性（R = 0.99；95%置信区间）；然而，一致性分析表明平均差异（Bias）为-0.11 对数 CFU/g（p < 0.05），表明 PC 方法存在低估。这表明存在应激或存活但非可培养（VBNC）细胞，可通过 PMA-qPCR 检测到，但不能通过 PC 检测到。巴尼安和罗伯茨模型显示，在所有等温条件下，PC 和 PMA-qPCR 数据均能很好地描述 STB 中鼠伤寒沙门氏菌鸡尾酒的行为。与 Ratkowsky 平方根模型相比，指数二次模型更能准确地表示最大比生长速率对温度的依赖性，两种方法的 R 值均≥0.984，RMSE 值均≤0.011。这些结果表明，与 PC 方法相比，结合 PMA-qPCR 和预测模型可以更准确地预测鼠伤寒沙门氏菌的生长。在肉类产品冷链中断的情况下，使用 PMA-qPCR 方法可以定量检测 VBNC 细胞，这些细胞仍会对消费者构成健康风险，尤其是在即食产品中。
