This work describes the development of a real-time polymerase chain reaction (RT-PCR) system for the detection and identification of Atlantic cod (Gadus morhua). Among the advantages of this technique, it is worth highlighting that this is reliable in terms of specificity and sensitivity. The TaqMan real-time PCR is the simplest, fastest testing process and has the highest potential for automation, therefore representing the currently most suitable method for screening, allowing the detection of fraudulent or unintentional mislabeling of this species. The method can be applied to all kinds of products, fresh, frozen, and processed products, including those undergoing intensive processes of transformation. The developed methodology using specific primer-probe set was validated and further applied to 40 commercial samples labeled as cod in order to determinate if the species used for their manufacturing corresponded to G. morhua, detecting 20% that were incorrectly labeled. A C(t) value of about 19 was obtained when G. morhua was present. In samples with a species mixture, all samples that had a fluorescence signal were positive (C(t) < 30) for the presence of G. morhua by conventional end-point RT-PCR, and the estimated limit of detection for these type of samples was of 20 pg of DNA. The methodology herein developed is useful to check the fulfilment of labeling regulations for seafood products and verify the correct traceability in commercial trade and for fisheries control.

No abstract

In the present study, two methods for the genetic identification of the most important seaweed species used for human consumption were developed. Both are carried out through PCR amplification of an 18S rRNA gene fragment. The first one is based on the phylogenetic analysis of DNA sequences (FINS), while the second is based on length polymorphism and RFLP visualized by means of an ALF system. The main novelty of this work lies in the fact that it allows genetic identification of the main commercial species of seaweed. Moreover, the developed systems can be applied to all kinds of processed products, including those that have undergone intensive transformation, as for instance canned foods. These methodologies also permit the detection of species in complex matrixes where more than one algal species is present. The methods were validated using products manufactured in a pilot plant showing correct functioning. Finally, the methods were applied to 23 commercial samples including some that had been subjected to intensive thermal treatment, allowing the detection of those that were incorrectly labeled (30%). Therefore, these molecular tools can be used for clarifying questions related to the correct labeling and traceability of commercial products that include some seaweeds in their composition.