Mitigating Cronobacter sakazakii safety risks associated with non-uniform reconstitution of infant formula using silica-immobilized phenolic compounds

Cronobacter sakazakii is a foodborne pathogen of major concern in powdered infant formula (PIF) due to its persistence, desiccation tolerance, and severe health impact on neonates. Although WHO/FAO guidelines recommend reconstituting PIF with water at ≥70 °C to inactivate potential contaminants, studies have shown substantial variability in domestic preparation practices, including suboptimal temperatures and inaccurate powder-to-water ratios. This lack of uniformity in reconstitution represents a critical safety gap that may allow C. sakazakii to survive and proliferate in reconstituted infant formula. This study evaluated the antimicrobial potential of silica particles functionalized with thymol or carvacrol against C. sakazakii , both when applied as dispersed system (1 × MIC and 2 × MIC) and as processing aids in packed beds of different heights (up to 14 cm). Experiments were conducted in phosphate-buffered saline and reconstituted infant formula at incubation temperatures up to 60 °C, to assess the intrinsic antimicrobial response of the functionalized particles and their performance under realistic application conditions, respectively. When applied as dispersed system in PBS or infant formula, functionalized particles (2xMIC) produced strong inactivation of C. sakazakii (> 3 log₁₀ reductions), combining lethal and sublethal damage. Filtration assays confirmed that higher bed heights (14 cm) and elevated temperatures (60 °C) enhanced antimicrobial performance. Importantly, these results demonstrate that functionalized particles could complement existing hygienic practices and mitigate the safety risks derived from non-uniform formula reconstitution, exploiting the mild thermal conditions already present during preparation. • SiO 2 -Thy and SiO 2 -Car were successfully synthesized via Mannich reaction. • Immobilized EOCs showed strong bactericidal activity against C. sakazakii • Packed-bed filtration enhanced inactivation even at low residence times. • Mild heat (45–60 °C) synergizes with immobilized EOCs to boost lethality. • SiO 2 -EOCs mitigates risks from non-uniform PIF reconstitution below 70 °C.