Microbiological risk assessment of Bacillus cereus in popular hot dishes eaten by plant-based diet consumers in France

Abstract

There is a current trend towards plant-based diets in Western countries. Since changes in the diet imply possible changes in exposure to foodborne pathogens, there is an increasing need to assess the microbiological risks associated with these diets. This study aims to assess microbiological risks for French adults associated with Bacillus cereus group III and group IV in hot, homemade cereal- and lentil-based dishes. A probabilistic retail-to-fork risk assessment model was developed considering cooking, cooling at ambient temperature, and storage under chilled conditions. Data came from a representative national survey, public database and literature. The model was developed in R, and uncertainty and variability were separated using second-order Monte Carlo simulations. Not all consumers have the same storage and cooling practices, so the results were expressed by probabilistic distributions built by specific storage time. The mean concentration of Bacillus cereus in portions at the time of consumption after 72 h of storage was 1.2 log CFU.g⁻¹ for cereal-based dishes and 3.4 log CFU.g⁻¹ for lentil-based dishes. After 72 h of storage under chilled conditions, the risk per portion, defined as the probability of contamination over 5 log CFU.g⁻¹, was 0 (95 % CI: 0 - 0) for cereal-based dishes and 7.95 × 10⁻⁴ (95 % CI: 5.55 × 10⁻⁴ - 1.12 × 10⁻³) for lentils-based dishes. However, if cooling time at room temperature reached 24 h, the risk for cereal- and lentil-based dishes increased to 2.39 × 10⁻³ (95 % CI: 1.15 × 10⁻³ - 4.90 × 10⁻³) and 4.66 × 10⁻¹ (95 % CI: 3.16 × 10⁻¹ - 6.07 × 10⁻¹), respectively. The sensitivity analysis indicated that the initial prevalence and level of contamination were key factors in limiting the risk, ranking before cooling time or refrigeration conditions. Besides, the scenario analysis revealed an influence of consumer behaviour regarding cooling and storage time on the risk per portion. The environmental trend towards plant-forward diets, combined with the emerging no-food waste and batch cooking practices in France, will likely favour new consumption patterns and increase the risk associated with Bacillus cereus. Our model will help quantify this extra burden.