Heat resistance of vegetative cells of psychrotrophic Bacillus cereus - Archive ouverte HAL
Communication Dans Un Congrès Année : 2016

Heat resistance of vegetative cells of psychrotrophic Bacillus cereus

Résumé

The aim of FP7-OPTIFEL project is to create new products based on fruits and vegetables, supplemented with nutrients to fight elderlies’ nutritional deficiencies. The microbial safety of these products is of great importance due to elderlies’ vulnerability. The foodborne pathogen Bacillus cereus can resist to pasteurization and psychrotrophic strains can multiply during food storage at low temperatures. Therefore we verified if psychrotrophic Bacillus cereus could be destroyed when reheating the food before consumption, by measure of the heat resistance of psychrotrophic Bacillus cereus vegetative cells. We studied six psychrotrophic strains belonging to three different phylogenetic groups (group II, V and VI) and two thermophilic strains (group VII) at temperatures representative of food reheating. These Bacillus cereus strains were cultivated in optimal condition and heat resistance was determined with vegetative cells in stationary phase. Bacillus cereus vegetative cells suspensions were heated at five or more different temperatures for five different heating times. Survival curves and thermal death curves were established and the kinetic parameters δ (decimal reduction time at temperature T) and Z (temperature dependence of δ) were derived by linear regression. At 48°C, δ value o vegetative cells of psychrotrophic strains varied from 3 to 8 min. For all strains, the heat-sensitivity (Z values) varied between 1.6 °C and 5.6 °C. Z value was not different among the Bacillus cereus phylogenetic groups, and similar between the psychrotrophic and thermophlic groups. These Z values were low compare to other bacteria, for example to Salmonella enterica Z value can varied between 7.71 and 11.19 and for Staphylococcus aureus between 7.46 and 13.98 (Amado et al., 2013). Six log 10 reduction of the most resistant psychrotrophic Bacillus cereus could be obtained by reheating 3 min at 53°C.
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Dates et versions

hal-01604557 , version 1 (02-10-2017)

Identifiants

  • HAL Id : hal-01604557 , version 1
  • PRODINRA : 403176

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Alizée Guérin, Claire Dargaignaratz, Veronique Broussolle, Thierry Clavel, Christophe Nguyen The. Heat resistance of vegetative cells of psychrotrophic Bacillus cereus. FoodMicro 2016, Jul 2016, Dublin, Ireland. ⟨hal-01604557⟩
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