Center for Meat Safety & Quality, Dept of Animal Sciences, Colorado State Univ, Fort Collins, CO 80523-1171, USA.
J Food Sci. 2012 Feb;77(2):M108-14. doi: 10.1111/j.1750-3841.2011.02552.x. Epub 2012 Jan 17.
Studies evaluated thermal inactivation of Escherichia coli O157:H7 inoculated at different depths of simulated blade-tenderized non-intact steaks. Fresh beef slices (0.3 or 0.6 cm thick) were stacked on top of each other to form 2.4 or 1.2 cm thick steaks. Steaks were blade-tenderized and then inoculated with rifampicin-resistant Escherichia coli O157:H7 (8 strain mixture; 4 log CFU/cm(2)) on the surface or between slices, vacuum-packaged, and stored at 4 or -20 °C for 5 d before cooking. Steaks were cooked by pan-broiling or roasting to a geometric center temperature of 60 °C. Frozen samples were either cooked from the frozen state or after thawing to approximately 4 or 25 °C. In steaks inoculated on the external surface and cooked by pan-broiling, pathogen survivors recovered from thinner (1.2 cm) steaks were greater (P < 0.05) than those recovered from thicker (2.4 cm) steaks. Cooking steaks from a frozen state or after thawing (4 or 25 °C) did not (P ≥ 0.05) affect extent of pathogen inactivation. Survivors after pan-broiling of 2.4 cm thick steaks increased (P < 0.05) from 0.3 to 1.3 log CFU/cm(2) for surface-inoculated steaks to 2.5 to 3.2 log CFU/cm(2) for samples inoculated at the center (1.2 cm depth). In comparison, overall thermal destruction of the pathogen in steaks cooked by roasting was less, and survivor counts were generally not different (P ≥ 0.05) at each depth of inoculation. These data should be useful in development of lethality guidelines to ensure safe consumption of non-intact meat products.
Results of this study should be useful for developing cooking guidelines, for foodservice establishments and consumers, to ensure safe consumption of non-intact meat products.
本研究评估了不同深度模拟切片嫩化非完整牛排中接种的大肠杆菌 O157:H7 的热失活动力学。新鲜牛肉切片（0.3 或 0.6 厘米厚）堆叠在一起形成 2.4 或 1.2 厘米厚的牛排。牛排被切片嫩化，然后在表面或切片之间接种 rifampicin 抗性大肠杆菌 O157:H7（8 种混合菌株；4 对数 CFU/cm²），真空包装，并在烹饪前在 4 或-20°C 下储存 5 天。牛排通过煎或烤至几何中心温度 60°C 进行烹饪。冷冻样品要么从冷冻状态烹饪，要么解冻至约 4 或 25°C 后烹饪。在外部表面接种并通过煎烤烹饪的牛排中，从较薄（1.2 厘米）牛排中回收的病原体幸存者（P <0.05）大于从较厚（2.4 厘米）牛排中回收的幸存者。从冷冻状态或解冻后（4 或 25°C）烹饪牛排不会（P≥0.05）影响病原体失活动力学的程度。2.4 厘米厚牛排煎烤后，表面接种牛排的幸存者数量从 0.3 增加到 1.3 对数 CFU/cm²（P <0.05），到中心（1.2 厘米深度）接种样品的幸存者数量增加到 2.5 至 3.2 对数 CFU/cm²。相比之下，通过烘烤烹饪牛排时对病原体的整体热破坏较少，并且每个接种深度的幸存者计数通常没有差异（P≥0.05）。这些数据对于制定杀菌指南以确保非完整肉类产品安全消费应该是有用的。
本研究的结果对于制定烹饪指南应该是有用的，适用于餐饮企业和消费者，以确保非完整肉类产品的安全消费。
