Efficacy of 405-nm LED illumination and citral used alone and in combination for the inactivation of Cronobacter sakazakii in reconstituted powdered infant formula

Abstract

Cronobacter sakazakii, a foodborne opportunistic pathogen, mainly affects neonates and infants, with mortality rates of 26.9%. Most outbreaks arise from powdered infant formula (PIF). The aim of this study was to investigate the efficacy and mechanism of 405-nm light-emitting diode (LED) and citral treatment used in combination against C. sakazakii in reconstituted PIF. LED-illumination combined with citral showed better antimicrobial effects than either treatment alone. In reconstituted PIF, the abundance of C. sakazakii cells was reduced by 6.5 log 10 CFU/mL following combined LED and 9 µL/mL citral treatment for 90 min compared with untreated controls, respectively. Combined LED and 6 µL/mL citral treatment destroyed C. sakazakii cellular morphology and membrane integrity, prolonged the recovery time of sublethally-injured cells, and induced lipid peroxidation. Besides, LED treatment decreased the amount of lipid peroxidation caused by citral treatment alone. Neither LED illumination nor citral treatment resulted in breakdown of C. sakazakii genomic DNA. Because of its safe, environmentally-friendly, economical, and high-performance characteristics, the combination of LED-illumination and citral treatment has the potential to be developed into a strategy to control C. sakazakii contamination in stored and reconstituted PIF.