Teagasc Food Research Centre, Ashtown, Dublin, D15 DY05, Ireland; School of Veterinary Medicine, University College Dublin, Belfield, Dublin, D04 N2E5, Ireland.
Environmental Sustainability and Health Institute, Technological University Dublin, Grangegorman, Dublin, D07 H6K8, Ireland.
Food Microbiol. 2023 Jun;112:104215. doi: 10.1016/j.fm.2023.104215. Epub 2023 Jan 9.
The increased detection of clinical cases of Clostridioides difficile coupled with the persistence of clostridial spores at various stages along the food chain suggest that this pathogen may be foodborne. This study examined C. difficile (ribotypes 078 and 126) spore viability in chicken breast, beef steak, spinach leaves and cottage cheese during refrigerated (4 °C) and frozen (-20 °C) storage with and without a subsequent sous vide mild cooking (60 °C, 1 h). Spore inactivation at 80 °C in phosphate buffer solution, beef and chicken were also investigated to provide D values and determine if PBS was a suitable model system for real food matrices. There was no decrease in spore concentration after chilled or frozen storage and/or sous vide cooking at 60 °C. Non-log-linear thermal inactivation was observed for both C. difficile ribotypes at 80 °C in phosphate buffer solution (PBS), beef and chicken. The predicted PBS D values of 5.72±[2.90, 8.55] min and 7.50±[6.61, 8.39] min for RT078 and RT126, respectively, were in agreement with the food matrices D values of 5.65 min (95% CI range from 4.29 to 8.89 min) for RT078 and 7.35 min (95% CI range from 6.81 to 7.01 min) for RT126. It was concluded that C. difficile spores survive chilled and frozen storage and mild cooking at 60 °C but may be inactivated at 80 °C. Moreover thermal inactivation in PBS was representative of that observed in real food matrices (beef and chicken).
艰难梭菌（Clostridioides difficile）临床病例的检出率不断增加，加上该病原体孢子在食物链的各个阶段都能存活，这表明艰难梭菌可能是食源性的。本研究在冷藏（4°C）和冷冻（-20°C）储存条件下，分别研究了鸡脯肉、牛排、菠菜叶和白软干酪中艰难梭菌（078 型和 126 型）孢子的活力，以及在有和没有随后的温和（60°C，1 小时）真空低温烹调法（ sous vide ）处理后的活力。还研究了在磷酸盐缓冲溶液、牛肉和鸡肉中 80°C 时孢子的失活情况，以提供 D 值，并确定 PBS 是否是实际食品基质的合适模型系统。在 60°C 冷藏或冷冻储存和/或 sous vide 烹饪后，孢子浓度没有下降。在磷酸盐缓冲溶液（PBS）、牛肉和鸡肉中，两种艰难梭菌的非对数线性热失活均观察到。在 PBS 中，预测的 RT078 和 RT126 的 D 值分别为 5.72±[2.90, 8.55] min 和 7.50±[6.61, 8.39] min，与 RT078 的食品基质 D 值 5.65 min（95%置信区间范围为 4.29 至 8.89 min）和 RT126 的 7.35 min（95%置信区间范围为 6.81 至 7.01 min）相符。研究结论为，艰难梭菌孢子能在 60°C 冷藏和冷冻储存及温和烹饪条件下存活，但在 80°C 可能失活。此外，PBS 中的热失活情况与实际食品基质（牛肉和鸡肉）中的观察结果一致。
