Quantitative risk assessment for hazards that arise from non-proteolytic Clostridium botulinum in minimally processed chilled dairy-based foods

A modular process risk model has been constructed that describes the manufacture of dairy dessert products and hazards that arise from non-proteolytic Clostridium botulinum. The model describes batch manufacture and consumer storage of a family size generic dairy dessert but includes a realistic quantification that could apply to a specific food product. The dairy dessert sector is an expanding part of the UK market. The model includes modules that describe spore loads in raw materials, spore inactivation during thermal processing, volume partition and the population kinetics for non-proteolytic C. botulinum during sequential isothermal storage regimes. Where possible elements of uncertainty and variability are identified explicitly. The model is constructed as a belief network from published data and expert opinions. The model provides marginal probabilities, and associated sensitivities, for a range of endpoint measures centred on the toxicity of a single retail unit after an extended period of storage. The decimal reduction time for non-proteolytic C. botulinum spore populations at the highest (hold) temperature of the primary thermal process and the highest temperature experienced during poorly controlled (consumer) storage are dominant factors determining risks. Priorities for additional information to support risk assessments have been identified.