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This study (open access) compared four different test approaches (DNA barcoding rbcL, DNA barcoding matK , ITS2 barcoding vs the NCBI database, ITS2 barcoding vs the BOLD database) in an authenticity survey of 100 herbal infusions on the Portuguese market.  Samples included 94 single-species products and six polyherbal formulations.

The authors report that DNA extraction was successful for 94 samples, while six single-species products failed to amplify any of the tested barcodes. Among the 88 remaining single-species samples, ITS2 showed the highest amplification success (100 %), outperforming the barcodes rbcL (94 %) and matK (84 %).

Sanger sequencing confirmed the labelled species in 69.3 % of cases with rbcL and 48.9 % with matK. While 63 samples would be considered authentic solely based on barcoding (i.e., if either rbcL or matK matched the label), ITS2 metabarcoding revealed that many of these contained additional undeclared species, indicating that barcoding alone overestimated product authenticity. Of the 85 samples successfully analysed by ITS2 metabarcoding, only 27 (32 %) fully matched their label, while 58 (68 %) contained either additional undeclared species or complete substitutions. Several products contained undeclared species in significant proportions, indicating potential economic adulteration.

The authors conclude that their results revealed (i) the importance of curated and comprehensive databases, with a higher number of species being identified by NCBI database, (ii) the superior sensitivity of ITS2 metabarcoding, and (iii) the widespread mislabelling in commercial herbal products.

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In this survey a total of 107 tuna cans were collected between 2020 and 2022 from 7 different Portuguese commercial brands.  Samples were purchased from main supermarket chains, large-scale distributors and local stores.  Samples were categorised by the quarter of the year when the tuna was canned (inferred from the expiry date) with each sample was tested in triplicate.  Extracted DNA was purified and iteratively tested using molecular metabarcoding methods.

The researchers report (open access) that the occurrence of different species was observed only in products canned in brine or water (i.e. all products canned in oil were Skipjack Tuna). Skipjack tuna was predominant across all canning liquids and brands analysed. Nonetheless, other species like Thunnus obesus and T. albacares, or Auxis spp. (not considered true tuna) were also detected. The use of different species was limited to cans produced during the second quarter of the year, which could reflect differences in seasonal availability of different tuna species or in sourcing strategies/market preferences of each company. For four brands, multiple species were detected inside the same can.  This violates current European legislation.

The researchers conclude that these results provide the first broad assessment of species used in the Portuguese tuna canning industry and showed the inclusion of vulnerable species is limited.

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