Effect of prior heat shock on heat resistance of Listeria monocytogenes in meat |
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Authors: | J M Farber B E Brown |
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Affiliation: | Microbial Research Division, Bureau of Microbial Hazards, Health and Welfare Canada, Ottawa, Ontario. |
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Abstract: | The effect of prior heat shock on the thermal resistance of Listeria monocytogenes in meat was investigated. A sausage mix inoculated with approximately 10(7) L. monocytogenes per g was initially subjected to a heat shock temperature of 48 degrees C before being heated at a final test temperature of 62 or 64 degrees C. Although cells heat shocked at 48 degrees C for 30 or 60 min did not show a significant increase in thermotolerance as compared with control cells (non-heat shocked), bacteria heat shocked for 120 min did, showing an average 2.4-fold increase in the D64 degrees C value. Heat-shocked cells shifted to 4 degrees C appeared to maintain their thermotolerance for at least 24 h after heat shock. |
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