Dual-photosensitizers photodynamic system for non-thermal inactivation of Shewanella putrefaciens and inhibition of microbial growth of refrigerated Litopenaeus vannamei

Aquatic products are highly susceptible to microbial contamination and spoilage during storage, while traditional thermal sterilization often compromises their nutritional and sensory quality. In this study, a non-thermal dual-photosensitizer photodynamic treatment system composed of curcumin and octyl gallate was developed and activated under 420 nm light. The synergistic action of the two photosensitizers significantly enhanced the generation of reactive oxygen species (ROS), resulting in a 3.30 log reduction in Shewanella putrefaciens counts via membrane disruption, intracellular leakage, and genomic DNA degradation. Furthermore, the curcumin/octyl gallate-photodynamic treatment system was incorporated into a chitosan-based coating and applied to Litopenaeus vannamei . This treatment significantly inhibited increases in total viable counts, TVB-N, TBARS, and pH, thereby effectively extending the refrigerated shelf life. Microbial community analysis revealed marked shifts in bacterial composition, with suppression of dominant spoilage genera such as Psychrobacter, Pseudomonas , and Shewanella , confirming the broad-spectrum antibacterial efficacy of the treatment. Overall, curcumin/octyl gallate-photodynamic treatment represents an innovative, low-dose, and high-efficiency non-thermal sterilization approach for seafood preservation, offering a feasible alternative to traditional methods while maintaining microbial safety and product quality.