Institute of Food Safety and Health, National Taiwan University, Taipei 100, Taiwan.
Institute of Food Science and Technology, National Taiwan University, Taipei 106, Taiwan.
Food Res Int. 2023 Feb;164:112316. doi: 10.1016/j.foodres.2022.112316. Epub 2022 Dec 9.
Chicken is a suspected reservoir of uropathogenic Escherichia coli (UPEC), resulting in foodborne urinary tract infections (UTIs). Sous-vide ready-to-eat (RTE) food products may be associated with microbial hazards due to the low-temperature long-time (LTLT) process. However, little is known regarding the survival of UPEC during sous-vide cooking. The aim of this study was to evaluate the heat resistance of UPEC in chicken breast during sous-vide processing and establish predictive inactivation models. Chicken breast samples were inoculated with a four-strain cocktail of UPEC, including reference strains from UTI patients and chicken isolates. The inoculated samples, with or without 3% NaCl solution for marination, were vacuum sealed in bags, immersed in a temperature-controlled water bath, and cooked at 50 °C, 55 °C, 60 °C, and 63 °C. The change in survival of populations of UPEC was fitted with the linear and Weibull inactivation models to obtain the survival curves at different temperatures; the D- and z-values were also calculated. The goodness-of-fit was evaluated using the root mean square error (RMSE), sum of squared errors (SSE), adjusted R, and Akaike information criterion (AIC). The results showed that the linear model with tail was better than the Weibull model in terms of fitting performance. With the addition of salt marinade, D-values at 50 °C, 55 °C, 60 °C, and 63 °C determined by the linear model with tail decreased from 299.78 to 166.93 min, 16,60 to 13.87 min, 4.06 to 3.05 min, and 1.05 to 0.87 min, respectively, compared with the controls. The z-values of control and salt-marinated samples were 6.14 °C and 5.89 °C, respectively. The model developed for predicting UPEC survival under sous-vide cooking was validated using an additional survival curve at 58 °C. The validation results showed that the RMSE was 0.122 and 0.133 log CFU/g, and the proportion of relative error was 0.875 and 0.750 in the acceptable prediction zones for the control and salt-marinated samples, respectively. In conclusion, the heat resistance of an emerging foodborne pathogen, UPEC, in sous-vide processed chicken breast was revealed for the first time. Our results showed that salt marinade (3% NaCl) increases the heat sensitivity of UPEC during the sous-vide processing. The developed survival functions based on the linear model with tail can be applied to control the thermal lethality of UPEC.
鸡肉是一种可能携带尿路致病性大肠杆菌（UPEC）的宿主，从而导致食源性尿路感染（UTI）。由于采用低温长时间（LTLT）工艺，准备即食（RTE）的真空低温烹饪食品可能存在微生物危害。然而，目前对于 UPEC 在真空低温烹饪过程中的存活情况知之甚少。本研究旨在评估 UPEC 在鸡胸肉真空低温烹饪过程中的耐热性，并建立预测失活动力学模型。采用包括来自 UTI 患者和鸡肉分离株的参考菌株的四株 UPEC 鸡尾酒对鸡胸肉样本进行接种。接种后的样本，用或不用 3%的盐水腌制，真空密封在袋子中，浸入控温水浴中，并在 50°C、55°C、60°C 和 63°C 下烹饪。采用线性和 Weibull 失活动力学模型拟合 UPEC 种群存活变化，以获得不同温度下的存活曲线；还计算了 D 值和 z 值。通过均方根误差（RMSE）、平方和误差（SSE）、调整 R 和 Akaike 信息准则（AIC）评估拟合优度。结果表明，在拟合性能方面，带尾巴的线性模型优于 Weibull 模型。添加盐腌料后，带尾巴的线性模型确定的 50°C、55°C、60°C 和 63°C 的 D 值分别从 299.78 分钟降至 166.93 分钟、1660 分钟降至 13.87 分钟、4.06 分钟降至 3.05 分钟和 1.05 分钟降至 0.87 分钟，而对照样品的 D 值分别为 299.78 分钟、1660 分钟、4.06 分钟和 1.05 分钟。控制样品和盐腌样品的 z 值分别为 6.14°C 和 5.89°C。使用 58°C 下的另一条存活曲线对开发的 sous-vide 烹饪中预测 UPEC 存活的模型进行了验证。验证结果表明，在可接受的预测范围内，对照样品和盐腌样品的 RMSE 分别为 0.122 和 0.133 log CFU/g，相对误差比例分别为 0.875 和 0.750。总之，首次揭示了新兴食源性病原体 UPEC 在鸡胸肉 sous-vide 加工过程中的耐热性。我们的结果表明，盐腌料（3%NaCl）增加了 UPEC 在 sous-vide 加工过程中的热敏感性。基于带尾巴的线性模型开发的生存函数可用于控制 UPEC 的热力致死率。
