Identification of tuna species in raw and processed products using DNA mini-barcoding of the mitochondrial control region

Accurate species identification methods are needed to combat tuna fraud, improve tuna stock regulation, and mitigate health risks associated with mislabeled tuna products. The objective of this study was to conduct a market survey of raw and processed tuna products using a DNA mini-barcoding system based on the mitochondrial control region (CR). A total of 80 samples of raw, dried, and canned tuna products were collected at the retail level for CR mini-barcoding analysis. The samples underwent DNA extraction, polymerase chain reaction (PCR), and DNA sequencing of the 236-bp CR mini-barcode. The resulting sequences were searched against GenBank using the nucleotide Basic Local Alignment Search Tool (BLAST) to determine the species. The study achieved species identification for 100% of the raw samples, 95% of the dried samples, and 50% of the canned samples, for an overall success rate of 86% (69/80 samples). Mislabeling occurred in 11 of the identified samples (16%), including 8 products marketed as raw, dried, or canned yellowfin tuna, 2 samples marketed as dried or canned skipjack tuna, and 1 raw fillet sold as bluefin tuna. Overall, the DNA mini-barcoding system proved to be a promising method in identifying tuna species in both raw and processed samples. However, testing with a secondary marker is required in some cases to resolve instances of possible species introgression. Future research should explore optimization of this method for improved identification of canned tuna samples.