Résumé :
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The behaviour of Listeria monocytogenes under chilling processes was investigated. Growth kinetics were measured at 7°C in TSBYE culture medium as a function of pH (7.2 and 6.2), pre-incubation temperatures (4 or 7°C), cooling (0.05 or 0.1°C min(-1)) and freezing (0 and -5°C) treatments. Growth curves generated were fitted by Gompertz and Baranyi functions. The Baranyi function gave better parameter estimation values than the Gompertz equation which over-estimated the specific growth rare values. Listeria monocytogenes grew at 7°C without a lag phase, except when the sub-culture was performed at 37°C, whereas the specific growth rate was affected by the chilling processes, In fact, L. Monocytogenes grew slightly faster at 7°C when a 4°C pre-incubation treatment was applied than with a 7°C pre-incubation treatment. These results suggest that to mimic the processes of cont amination in industry, predictive microbiology studies with L. Monocytogenes should be performed with organisms cultured at low temperatures.
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