Antibacterial mechanism and preservation effect of curcumin-based photodynamic extends the shelf life of fresh-cut pears

Foodborne pathogen is a major threat to human health. In this study, we evaluated the bactericidal efficacy of curcumin-based photodynamic inactivation (PDI) against Listeria monocytogenes, elucidated its underlying bactericidal mechanisms including membrane damage, oxidative stress and protein degradation. Depending on curcumin concentration and illumination duration, the reactive oxygen species (ROS) increased rapidly after PDI treatment, resulting in severe cell membrane damage and protein degradation. Meanwhile, the activity of ROS defense enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) was inhibited significantly (p < 0.05), amplifying the oxidative damage to bacteria. Besides, fresh-cut pears were treated by PDI and then stored at 4 °C for 6 d to investigate the changes of color and hardness. The populations of L. monocytogenes on fresh-cut pears were significantly (p < 0.05) reduced by 3.43 log CFU/g after PDI without causing quality deterioration. After storage for 6 d, pears treated by PDI remained higher (p < 0.05) L* (60.91 ± 4.48) and hardness (51.19 ± 3.77 N). These results suggested that curcumin-based PDI to inactivate foodborne pathogens could be applied as a potential food safety technology.