Inactivation of Listeria monocytogenes, Escherichia coli O157:H7, and Staphylococcus aureus by sequential light-emitting diodes (LEDs) treatment at 365?nm and 420?nm
Published:19 November 2024
DOI: 10.1016/j.foodres.2024.115352
Jie Xiao, Hongchao Zhang
Abstract
Frequent outbreaks caused by foodborne pathogens pose long-term risks to consumer health. To proactively reduce the load of pathogenic bacteria during food processing, a novel light-based antibacterial approach was developed by sequential application of 365?nm and 420?nm light-emitting diodes (LEDs). Results demonstrated that after treatment with 365?nm (480?J/cm2) followed by 420?nm (307.2?J/cm2), the reduction of Listeria monocytogenes reached 4.05?±?0.31?log?CFU/mL, significantly higher (an additional 1.8?log?CFU/mL, P?<?0.05) than cumulative reductions achieved by each 365?nm (2.25?±?0.92?log?CFU/mL) and 420?nm (0.02?±?0.15?log?CFU/mL) treatments. Further analysis revealed that the enhancement in bacterial reduction achieved through the sequential treatment with 365?nm and 420?nm was primarily driven by the exposure time to 365?nm. The inactivation mechanisms were investigated, considering possible photothermal, physical, and oxidative effects. Findings showed that the antibacterial effect of sequential treatment was mainly ascribed to intracellular oxidation generated by reactive oxidative species (ROS), namely hydrogen peroxide and superoxide anion. The antibacterial mechanism of two LEDs may result from the sensitization of bacterial cells to excessive ROS, as evidenced by fluorescent intensity measurements and chemical scavenger assays. This research provides new insight for improving the efficacy of UVA and blue light treatment to control food contamination by Listeria.