Simple PCR-RFLP detection method for genus- and species-authentication of four types of tuna used in canned tuna industry

A simple method for authentication of processed tuna products is not only for testing against fraudulent practices in the tuna industry but being a promising tool for enhancing traceability. Here, a method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) had been developed using a part of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene as a key region for genus-and species-identification. The analysis was based on the different RFLP patterns of TaqI and HaeIII digested COI DNA from the four tuna species; i.e. Kasuwonus pelamis, Thunnus alalunga, Thunnus albacares, and Thunnus obesus, respectively. While the conventional PCR-RFLP worked effectively in raw tuna meat, a method of semi-nested PCR had to be developed in order to increase efficiency in the detection in cooked meat from canned product. The semi-nested PCR-RFLP pattern of COI DNA allowed the detection of 10% contamination of K. pelamis in canned tuna of other higher-valued species.