Photodynamic inactivation using natural pigments: Dual-ROS mechanisms, delivery strategies, and applications in food preservation

Growing demand for additive-free preservation has intensified safety concerns for fresh-cut and minimally processed foods. This review synthesizes current evidence on natural pigments as light-activated antimicrobial agents in food systems via photodynamic inactivation (PDI). Under food-grade visible light, these pigments generate reactive oxygen species (ROS) through Type I and Type II pathways, producing oxidative damage to microbial membranes, proteins, and nucleic acids. We compare performance across pigments—curcumin, chlorophyllin, anthocyanins, and bisdemethoxycurcumin (BDMC)—microorganisms, and food matrices, highlighting how molecular structure, formulation, and matrix interactions shape outcomes. Delivery strategies including nanoencapsulation, edible coatings, and photoactive packaging improve stability, enable surface-localized action, and modulate ROS release while maintaining sensory quality. We also summarize safety evaluations and the regulatory landscape, alongside practical ranges of illumination wavelength, dose, and exposure time reported in model and real-food studies. Remaining challenges involve pigment photostability, unintended oxidation in complex matrices, and regulatory uncertainty. Future work should prioritize rational carrier design, standardized illumination protocols, and harmonized safety testing to accelerate industrial translation of pigment-mediated PDI as a residue-free approach to extend shelf life and improve food safety. • Explains dual Type I and Type II ROS pathways for microbial inactivation. • Links pigment structure, formulation, and matrix to antimicrobial outcomes. • Shows nanoencapsulation, coatings, and packaging improve pigment stability. • Defines practical visible-light ranges for food applications and safety balance. • Summarizes biosafety data and regulatory considerations for food pigments.