Development of a multiplex PCR–ELISA method for the genetic authentication of Thunnus species and Katsuwonus pelamis in food products

• This paper describes a method for the genetic authentication of Thunnus species and Katsuwonus pelamis in food products.
• The method is based on PCR–ELISA methodology.
• The method comprises all the Thunnus species and Katsuwonus pelamis.
• The proposed method was validated and can be applied to commercial products, even to mixtures of fish species.
• The proposed method was validated and can be applied to commercial products with total reliability.

In the present work a PCR–ELISA technique for the authentication of Thunnus species was developed. This method is composed by four systems that can be used in a hierarchical way allowing the identification of several scombroids species; or each individual system independently. The hierarchical strategy, proposes a first step, to assign one sample to the Thunnus genus. Next, if the result is positive, several tests can be applied to assign the sample to some particular species of the Thunnus genus. In the case that the result is negative (absence of Thunnus species), it is possible to verify if Katsuwonus pelamis is included in the sample. The method even allows the detection of mixtures of these species in relatively low amounts (up to 1%). Finally, this method was applied to 11 commercial samples to verify the labelling status of tuna products in the market, detecting that 18% were mislabelling.