Performance assessment of ISO 23036-1:2021 for parasite detection in the seafood industry

A verification plan was carried out to assess the reliability of seafood companies (operators) in complying with the standard ISO 23036-1:2021, an international voluntary benchmark method specifically designed for detecting zoonotic Anisakidae larvae in fish musculature (edible part). This plan involved the intensive inspection of 19,465 individual fish across various sample batches (three consecutive one year projects), fish species, NE Atlantic fishing grounds and seasons. A verification process was carried out on 5600 fish pressed portions, which were primarily inspected by operators at their own facilities, followed by independent quality control at the IIM-CSIC, an experienced research lab acting as verifier. Sample and data traceability were made possible by the Biobank Technical Unit (UTB-IIM-CSIC), which previously trained the staff of operators and provided complete technical assistance and mentoring on critical control points along the verification process. Performance evaluation was based on the level of agreement between operator findings and those of the verifier, both in parasite detection and counting. While numerical discrepancies (i.e. different number of anisakid larvae detected by the operator and the verifier) reached up to 22.8%, critical false positives and negatives were relatively low at 2.5% and 1.7%, respectively. Two main sources of error were identified: a) faults related to deviations from the ISO procedure, and b) misinterpretations of fluorescence signals, stemming from limitations in technical skill. Both error types were traced back to staff competence and the need for more continuous robust training. Overall, the verification plan yielded promising results, demonstrating that ISO 23036-1: 2021, if properly used, is a reliable tool that should be incorporated in HACCP for controlling fish parasite hazards at the seafood industry.