# The photodynamic inactivation in the control of the seafood zoonotic parasite, Anisakis sp

## TL;DR

This study shows that photodynamic inactivation using a specific chemical can effectively kill Anisakis larvae in seafood, offering a safer alternative to traditional methods.

## Contribution

The study introduces photodynamic inactivation with TMPyP as a novel method for controlling Anisakis larvae in seafood.

## Key findings

- 100% mortality of Anisakis larvae was achieved using PDI with TMPyP under specific conditions.
- Larvae showed severe intestinal damage after treatment, indicating effective inactivation.
- PDI could be a viable alternative to freezing for ensuring seafood safety.

## Abstract

Anisakis spp. L3 larvae commonly found in marine fish species are an important biological hazard when raw or inadequately thermally processed fishery products are consumed with live larvae, highlighting the need for effective control strategies. This study evaluated the efficacy and mechanism of photodynamic inactivation (PDI) of Anisakis L3 larvae, using the cationic photosensitizer (PS) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin tetraiodide (TMPyP). Larvae were collected from Atlantic horse mackerel and grouped by size: batch A (larvae ≈ 1.5 cm) and batch B (larvae ≈ 2.0 cm). Inactivation assays were performed in microcosms at 50 µM of TMPyP under different conditions: incubation times (15 min to 21 h); incubation temperatures (0.5 and 22 °C); irradiation period (2–8 h) and light irradiance (4, 14 and 67 mW/cm2). Viability and tissue damage of the larvae were assessed at post-treatment. In both batches, 100% of larvae mortality was achieved after 21 h of dark incubation at 22 °C with TMPyP, followed by 6–8 h of white light irradiation at 67 mW/cm2. Similar results were observed in batch B, when the dark incubation was performed at 0.5 °C. Notably, batch B, larvae showed more exuberant cytotoxic effect, including severe damage of the intestinal epithelium, leading to loss of the characteristic triradiate appearance. These findings indicate that PDI using TMPyP is effective in inactivating Anisakis larvae and could be a potential alternative to freezing for ensuring the safety of fishery products in the food industry.