Development of a rapid and simple molecular identification methodology for true sardines (Sardina pilchardus) and false sardines (Sardinella aurita) based on the real-time PCR technique

Abstract

Sardines are a small pelagic species belonging to the Clupleidae family and have high commercial value because of the properties of their meat. One of the most valuable fish in this family is Sardina pilchardus, which in addition to its high commercial value is the one that should be labeled on canned sardines, the other species being labeled as sardines X. In this study, a fast real-time polymerase chain reaction (PCR) assay based on TaqMan probe technology, which amplifies a fragment of the internal transcribed spacers (ITS1 and ITS2) and the 5.8 S rRNA region, was developed for the authentication of two commercially important species of sardines, S. pilchardus and S. aurita. This methodology can be applied to a variety of products, including those that have been subjected to intensive processing treatments such as canning. The present methodology was validated and subsequently applied to 50 commercial samples in order to determine whether correct labeling is being carried out in the market. This assay combines the high specificity, sensitivity, and rapidity of fast real-time PCR with the advantages of using two different probes in the same reaction, making it a powerful tool for verifying the correct application of food labeling regulations.