Foodborne outbreaks have emerged as a major safety concern in Indonesia’s Free Nutritious Meal (Makanan Bergizi Gratis or MBG) Program. The 2025 national risk profile documented 219 outbreaks and Bacillus cereus accounted for 38.30% of confirmed agents and was frequently associated with rice-based foods. Among 21 quantitative B. cereus measurements, the median outbreak-associated concentration was 1.65x104 CFU/g (5x101–3.6x108 CFU/g)(1). This study aimed to translate these surveillance findings into time–temperature-dependent predictions of B. cereus growth in cooked rice. The validated Baranyi–modified Ratkowsky model developed by Juneja et al. for B. cereus growth in cooked rice was computationally reproduced(2). Initial contamination (N0) was constrained using naturally contaminated cooked-rice data from Komprda et al. and inverse calibration, yielding an uncertainty distribution of simulated N0 Triangular (−0.112, 0.088, 0.288) log₁₀ CFU/g(3). Monte Carlo uncertainty analysis was performed using 100,000 iterations for each of 36 fixed time–temperature scenarios (15–40°C; 1–6 h). The MBG outbreak-associated median concentration (4.217 log₁₀ CFU/g) was used as an empirical benchmark. After 6 h, median predicted concentrations were 0.94, 2.26, 3.45, and 3.84 log₁₀ CFU/g at 25, 30, 35, and 40°C, respectively. At 40°C for 6 h, the 95% uncertainty interval was 3.68–3.99 log₁₀ CFU/g. None of the 100,000 simulations within the 1–6 h scenarios reached the MBG outbreak-associated median concentration. The estimated median times to reach this empirical benchmark were approximately 9.0 h at 30°C, 6.9 h at 35°C, and 6.4 h at 40°C. Integration of national outbreak surveillance with predictive microbiology demonstrates that both initial contamination and post-cooking time–temperature exposure strongly influence predicted B. cereus concentrations. These findings suggest that outbreak-level contamination may require longer favorable growth conditions, higher initial contamination, or additional process failures. MBG-specific measurements of initial contamination and actual time–temperature histories are needed to strengthen population-level risk predictions.
Keywords: Free Nutritious Meal; foodborne outbreak; Bacillus cereus; predictive microbiology.