What is in your cup of tea? DNA Verity Test to characterize black and green commercial teas

Abstract

In this study, we used several molecular techniques to develop a fast and reliable protocol (DNA Verity Test, DVT) for the characterization and confirmation of the species or taxa present in herbal infusions. As a model plant for this protocol, Camellia sinensis, a traditional tea plant, was selected due to the following reasons: its historical popularity as a (healthy) beverage, its high selling value, the importation of barely recognizable raw product (i.e., crushed), and the scarcity of studies concerning adulterants or contamination. The DNA Verity Test includes both the sequencing of DNA barcoding markers and genotyping of labeled-PCR DNA barcoding fragments for each sample analyzed. This protocol (DVT) was successively applied to verify the authenticity of 32 commercial teas (simple or admixture), and the main results can be summarized as follows: (1) the DVT protocol is suitable to detect adulteration in tea matrices (contaminations or absence of certified ingredients), and the method can be exported for the study of other similar systems; (2) based on the BLAST analysis of the sequences of rbcL+matK±rps7-trnV(GAC) chloroplast markers, C. sinensis can be taxonomically characterized; (3) rps7-trnV(GAC) can be employed to discriminate C. sinensis from C. pubicosta; (4) ITS2 is not an ideal DNA barcode for tea samples, reflecting potential incomplete lineage sorting and hybridization/introgression phenomena in C. sinensis taxa; (5) the genotyping approach is an easy, inexpensive and rapid pre-screening method to detect anomalies in the tea templates using the trnH(GUG)-psbA barcoding marker; (6) two herbal companies provided no authentic products with a contaminant or without some of the listed ingredients; and (7) the leaf matrices present in some teabags could be constituted using an admixture of different C. sinensis haplotypes and/or allied species (C. pubicosta).

Comparative assessment of the quality of commercial black and green tea using microbiology analyses

“…Tea sampling was the same of De Castro et al [ 8 ]. Briefly, a total of 32 tea packages ( C. sinensis ) were purchased from market in Naples (southern Italy) and online-shops (Table 1 ).…”

“…The research is part of a wider project consisting on a multi-faceted pilot study aimed to analyze 32 brands of European and Italian commercially available tea (16 black teas and 16 green teas) to evaluate: the presence of heavy metals and phthalates (Ferretti V, unpublished data); and adulterations (food fraud) through the a rapid and efficient protocol using DNA barcode (DNA Verity Test) [ 8 ].…”

Authentication of holy basil using markers relating to a toxicology-relevant compound

“…As part of self-optimisation, it has become popular as so-called "adaptogen" [7]. However, one of the drawbacks of "superfoods" is that they are prone to food fraud, and Holy Basil is not an exception [8][9][10]. Food fraud, in the strict sense, is the deliberate and intentionally illicit replacement of a declared food product by a surrogate for the sake of economic profit, for example, by adulteration and mislabelling [11].…”

Peer Review #1 of "Using high-resolution melting to identify Calliphoridae (blowflies) species from Brazil (v0.1)"

“…DNA Barcoding, a powerful molecular tool, was created to overcome these barriers. Based on one or more standardized DNA regions -the mitochondrial Cytochrome Oxidase I gene (COI) in the case of animals (Hebert et al 2003a), and chloroplastidial and nuclear regions for plants (CBOL Plant Working Group et al 2009;Kress et al 2005) and fungi (Schoch et al 2012) -Barcoding allows identifying the species with enough accuracy and is applicable to many areas such as tracking of adulterations in food (Dawnay et al 2016), beverages (Castro et al 2017), medicinal herbs (Bansal et al 2018), identification of flies in forensic area (Jang et al 2019;Oliveira et al 2017;Rolo et al 2013) and species that cannot be determined morphologically (Klippel et al 2015), among others.…”