Open AccessImpact of Vacuum Cooling onEscherichia coliO157:H7 Infiltration into Lettuce Tissue
Author(s) -
Haiping Li,
Mehrdad Tajkarimi,
Bennie Osburn
Publication year - 2008
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.02811-07
Subject(s) - escherichia coli , leafy , infiltration (hvac) , sterilization (economics) , bacteria , biology , food science , leafy vegetables , horticulture , microbiology and biotechnology , materials science , biochemistry , genetics , gene , monetary economics , economics , composite material , foreign exchange market , foreign exchange
Vacuum cooling is a common practice in the California leafy green industry. This study addressed the impact of vacuum cooling on the infiltration ofEscherichia coli O157:H7 into lettuce as part of the risk assessment responding to theE. coli O157:H7 outbreaks associated with leafy green produce from California. Vacuum cooling significantly increased the infiltration ofE. 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 ofE. coli O157:H7 internalization. Vacuuming also caused a lower reduction rate ofE. coli O157:H7 in stored lettuce leaves than that for the nonvacuumed condition.