A Critical Synthesis of Natural Photosensitizers in Photodynamic Food Preservation Covering Mechanisms, Matrix-Specific Applications, and Translational Barriers.

Photodynamic inactivation (PDI) is a promising nonthermal approach for food decontamination, but its translation from laboratory demonstration to industrial use remains constrained by photosensitizer chemistry, matrix optics, oxygen availability, and regulatory uncertainty. This review critically evaluates three food-relevant natural photosensitizer classes, curcumin, riboflavin, and chlorophyll derivatives, and compares their mechanisms, formulation needs, and application outcomes across produce, beverages, seafood, meat, dairy, and packaging systems. The reported efficacy is strongly matrix-dependent: reductions approaching 3-6 log CFU occur mainly in optically favorable, well-controlled systems, whereas opaque, turbid, protein-rich, lipid-rich, or geometrically complex foods commonly show lower and less reproducible inactivation. Sensory and nutritional quality must therefore be assessed together with microbial outcomes rather than assumed to be preserved. Nanoencapsulation, molecular complexation, and active packaging improve dispersibility, localization, and photostability, but they do not remove the fundamental light-penetration limit that confines PDI largely to surface, near-surface, or thin-layer applications. The review identifies standardized photodose reporting, matrix-stratified efficacy benchmarking, pilot-scale validation, residue and photoproduct assessment, and regulatory alignment as the most urgent priorities. Overall, the natural photosensitizer PDI should be positioned not as a universal substitute for established hurdles but as a precision, matrix-matched decontamination tool within integrated preservation systems.