Thursday, May 12, 2016: 4:00 PM
Kokkali Room (Megaron Athens International Conference Center)
Alizée Guérin, INRA, Avignon university, UMR408 Sécurité et Qualité des Produits d'Origine Végétale, F-84000 Avignon, France, Avignon, France
Claire Dargaignaratz, INRA, Avignon university, UMR408 Sécurité et Qualité des Produits d'Origine Végétale, F-84000 Avignon, France, Avignon, France
Véronique Broussolle, INRA, Avignon university, UMR408 Sécurité et Qualité des Produits d'Origine Végétale, F-84000 Avignon, France, Avignon, France
Thierry Clavel, Avignon university,INRA, UMR408 Sécurité et Qualité des Produits d'Origine Végétale, F-84000 Avignon, France, Avignon, France
Christophe Nguyen-the, INRA, Avignon university, UMR408 Sécurité et Qualité des Produits d'Origine Végétale, F-84000 Avignon, France, Avignon, France
Introduction: The aim of the FP7-OPTIFEL project is to create new food products based on fruits and vegetables, supplemented with specific nutrients to fight elderlies’ nutritional deficiencies. The microbial safety of these products is of great importance due to the high risk of foodborne disease in the elderly population. The foodborne pathogen
Bacillus cereus can resist pasteurization treatments, psychrotrophic strains can multiply during food storage at low temperatures, and some may produce the heat resistant emetic toxin cereulide.
Purpose: Understanding B. cereus behaviour during the life cycle of the food products.
Methods: We determined the growth ability of two psychrotrophic B. cereus strains KBAB4 and ADRIA I21 in BHI medium at various pH values between 5.0 and 7.0, with and without oxygen, at 8°C and 10°C. We also investigated the possibility for the two emetic psychrotrophic B. cereus MC 67 and BtB2-4 strains to produce the emetic toxin (cereulide) from 8°C to 25°C and at various pH values. We finally analysed the heat-resistance of the vegetative cells of six psychrotrophic and two thermophilic strains of B. cereus during food reheating.
Results: Combination of anaerobiosis, pH<5.7 at 10°C, or anaerobiosis at any pH and temperatures < 8°C prevented psychrotrophic Bacillus cereus growth. The LC-MSMS analysis showed that the production of cereulide began during the stationary phase of bacterial growth and that low pH and low temperatures limited its production. At 48°C, D value of 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.
Significance: These data on B. cereus cell behaviour will be used as guidance to help new product development.
