Li Haiping, Tajkarimi Mehrdad, Osburn Bennie I
Western Institute for Food Safety and Security, School of Veterinary Medicine, University of California Davis, Davis, California 95616, USA.
Appl Environ Microbiol. 2008 May;74(10):3138-42. doi: 10.1128/AEM.02811-07. Epub 2008 Mar 14.
Vacuum cooling is a common practice in the California leafy green industry. This study addressed the impact of vacuum cooling on the infiltration of Escherichia coli O157:H7 into lettuce as part of the risk assessment responding to the E. coli O157:H7 outbreaks associated with leafy green produce from California. Vacuum cooling significantly increased the infiltration of E. coli O157:H7 into the lettuce tissue (2.65E+06 CFU/g) compared to the nonvacuumed condition (1.98E+05 CFU/g). A stringent surface sterilization and quadruple washing could not eliminate the internalized bacteria from lettuce. It appeared that vacuuming forcibly changed the structure of lettuce tissue such as the stomata, suggesting a possible mechanism of E. coli O157:H7 internalization. Vacuuming also caused a lower reduction rate of E. coli O157:H7 in stored lettuce leaves than that for the nonvacuumed condition.
真空冷却在加利福尼亚绿叶蔬菜产业中是一种常见做法。作为对与加利福尼亚绿叶蔬菜相关的大肠杆菌O157:H7疫情进行风险评估的一部分，本研究探讨了真空冷却对大肠杆菌O157:H7渗入生菜的影响。与非真空处理条件（1.98E+05 CFU/g）相比，真空冷却显著增加了大肠杆菌O157:H7渗入生菜组织的量（2.65E+06 CFU/g）。严格的表面消毒和四重清洗无法消除生菜内部的细菌。似乎真空处理强行改变了生菜组织的结构，如气孔，这表明了大肠杆菌O157:H7内化的一种可能机制。真空处理还导致储存生菜叶中大肠杆菌O157:H7的减少率低于非真空处理条件。
