Case study n°2

Clostridium perfringens in prepared dishes served in catering

Food safety is crucial in catering in consideration to the huge number of meals served every year (5.6 109 meals/year in France). Meals can be provided by central kitchens to catering facilities through either a warm chain – prepared dishes are kept hot from cooking until consumption – or a chill chain – food are cooked, cooled down as soon as cooked, kept cold, transported to the catering facilities and reheated just before serving. With the chill chain procedures a very large number of meals (thousands per day and per kitchen) are prepared in the central kitchens and delivered within 1 to 3 days to other locations, where they are served to the consumers.

Cooling down, reheating and distribution operations were identified as main causative factors for Clostridium perfringens outbreaks that occurred in the chill chain system. For preventing this health risk, public health authorities enforce defined temperatures-time combinations but may approve other combinations if the food business operator can demonstrate that the appropriate degree of food safety is achieved. For the operators, compliance to the present regulation involves organizational difficulties and heavy investment of high energy consumption equipment for rapid cooling. Furthermore providing the validation of alternative procedures can be quite difficult for them.

The purpose of this study is to help food business operators by developing a methodical approach in order to connect “hazard based” control measures (PRPo, CCP) to “risk based” targets (PO, FSO). Therefore a methodology will be defined for evaluating the impact of physical parameters (temperature, time) on end product microbial food safety. Eventually process procedures will be optimized to achieve the same or even a higher end product food safety.

Targets established by governments in relation to public health goals could be “The maximum frequency and/or concentration of a hazard in a food at the time of consumption” (food safety objective, FSO) or “at a specified step in the food chain before the time of consumption” (performance objective, PO) (Codex Alimentarius Procedural Manual, 15th ed. 2004). FSOs and Pos should be established “to provide or contribute to the appropriate level of protection” (ALOP) to which the regulatory body does refer. Targets might be also expressed so as to account for the distribution of the hazard concentration, as suggested in the report of a meeting of the WHO Collaborating Centre on Risk Assessment at RIVM (Bilthoven, The Netherlands, 2006-12-01).