Comparative study of DNA extraction to initiate harmonized protocol for a simple method of species identification: Fresh and canned Tuna case study

Abstract

Seven different methods of DNA extraction were performed and compared in order to have the better DNA recovery in terms of quality and quantity. A PCR assay was realised based on the Cytb mitochondrial gene to identify 53 commercial food products of wide range diversity (Scombridae Thunnus species) commercialised in the Tunisian market, and we checked whether these products were correctly labelled under European and national legislations. Phylogenetic analyses on Cytb mitochondrial gene were used to study the relationships among the considered species. Tuna species was easily differentiated and confirmed by direct sequencing. The results showed a high deficiency in labelling: 96% of canned tuna did not specify the species, although the name of the species had to be mentioned. Partial least squares regression (PLS) showed relatively high values (45%) in all analysed data, suggesting substantial difference between the extraction procedures and matrices with SDS/PCI method being the most convenient.