Salmonella in microgreens: quantitative modeling of Salmonella Enteritidis in a controlled environment system

Microgreens have become popular due to their nutritional content and simple production requirements. Salmonella spp. is frequently associated with microgreens recall. This study was divided into two parts: (i) detection of Salmonella spp. and Enterobacteriaceae in commercial microgreens; (ii) simulate a controlled environment to assess Salmonella Enteritidis survival during cultivation and storage of microgreens. Among 122 samples, Enterobacteriaceae counts ranged from 2.70 to 7.49 log CFU/g, and Salmonella spp. was detected in sunflower and radish. Salmonella reached 8.31 Log CFU/g and 7.73 Log CFU/g in mustard and sunflower substrate, respectively. The maximum growth rate (μ_max) in the substrate was 0.94 h^-1 for mustard and 0.81 h^-1 for sunflower, and the lag phase was higher in sunflower (lag = 5.9 h) than in mustard (lag = 3.8 h). Regarding microgreens, initial counts were 8.17 in mustard and 5.41 Log CFU/g in sunflower, with slight reductions by harvest (maximum inactivation rate (k_max) = 0.01 and 0.03 h^-1; growth/inactivation potential (δ) = -0.39 and - 0.79 log CFU/g, respectively). The mustard microgreens system showed residual irrigation water, and Salmonella increased δ = 0.58 log CFU/mL with μ_max = 0.02 h^-1. In storage at 5 °C, Salmonella showed a slight reduction in mustard (k_max = 0.04 h^-1, δ = -0.21) and a higher reduction in sunflower (δ = -1.37, k_max = 0.10 h^-1). Scanning electron microscopy revealed bacterial adhesion to surface crevices, depressions, and near stomata, suggesting potential internalization. These findings highlight contamination risks in microgreen production and underscore the importance of preventive measures during cultivation, irrigation, and postharvest storage.