Photodynamic inactivation in food systems: A review of its application, mechanisms, and future perspective

Foodborne illnesses caused by pathogenic microorganisms, food loss and waste caused by spoilage microorganisms, and the occurrence of antibiotic-resistant bacteria are of the greatest public concerns. Photodynamic inactivation (PDI) is a promising technology for mitigating the above challenges. Given the rapid advances in PDI and its increasing popularity in food decontamination, a comprehensive and updated review is needed to summarize the antimicrobial mechanisms of PDI against food-related microorganisms. This review discusses the principle behind PDI, its application in food decontamination and preservation, antimicrobial mechanisms, and impact on innate antimicrobial susceptibility of microorganisms. Special emphasis is given to the antimicrobial mechanisms of PDI, its biological targets, and impacts. The chemistry behind PDI is the production of reactive oxygen species through the activation of endogenous or exogenous photosensitizers. PDI has proven its efficacy against pathogenic and spoilage bacteria, fungi, viruses, and spores in a variety of food and food contact surfaces. PDI's major antimicrobial mechanisms include disruption of cell structure and function, oxidation of macromolecules, inhibition of quorum sensing, disruption of biofilm, and attenuation of virulence factors. Development of PDI resistance is unlikely because of its multitargeted nature. Projects that investigate the long-term impacts of PDI treatments on food quality and safety as well as on human health, optimization of application parameters, and effective transformation of the laboratory-scale design to industrial-scale production are still needed for more advanced application of PDI in food systems.