DNA barcoding as an approach for species traceability and labeling accuracy of fish fillet products in Thailand

The lack of regulations and serious enforcement in the traceability of fishery products in some countries is one cause of food fraud, especially species substitution. Thailand is one of those countries where regulations are not fully enforced. Therefore, the labeling situation needs to be investigated in fish fillet products. Fifty-four products were collected from several supermarkets in Thailand. The labeling and molecular identity of each product were assessed by the application of a DNA barcoding technique on a cytochrome c oxidase I (COI) gene fragment of approximately 650 bp. All samples were successfully identified at the species level with 98-100% similarity in both the GenBank and BOLD databases. Only one sample could be identified at the genus level because the highest COI sequence match in the database was reported only at the genus level. Among all products, there were 25 species and 18 genera. Only one species, Pangasianodon hypophthalmus, was assessed as an endangered species according to IUCN status. FishBase was utilized to investigate the scientific names from common or market names. Two criteria were used to determine mislabeling, including i) mismatches between the scientific name identified by DNA barcoding and product labels and ii) the absence of common or market names in FishBase. Eighteen samples (33.33%) were mislabeled, which included 16 samples (88.89%) and 2 samples (11.11%) for criteria 1 and 2, respectively. Only one (11.11%) of nine products labeled with scientific names was mislabeled. Therefore, labeling products with scientific names may be a tool to reduce mislabeling to protect consumer rights.

Automated summary

The lack of regulations and enforcement in the traceability of fishery products, particularly species substitution, is a cause of food fraud in some countries. Thailand is one of these countries where regulations are not fully enforced. This study investigated the labeling situation of fish fillet products by assessing the molecular identity of 54 samples using a DNA barcoding technique. Results showed that 18 samples (33.33%) were mislabeled, mainly because the scientific names did not match the product labels.