Grace Young, Catherine Gamble, and Rohan Kirpekar inspect tea labels.

• Mark Y. Stoeckle, The Rockefeller University
• Catherine C. Gamble, Trinity School
• Rohan Kirpekar, Trinity School
• Grace Young, Trinity School
• Selena Ahmed, Tufts University
• Damon P. Little, The New York Botanical Garden

Key terms

Tea. Infusions prepared from leaves of the tea plant, Camellia sinensis, an evergreen flowering tree native to mountainous regions of southwestern China and neighboring countries.

Herbal “tea.” Infusions prepared from a diversity of other plants.

DNA barcoding. Identifying species using a short DNA sequence from a uniform locus in the genome. For land plants, the agreed-upon standard loci are rbcL and matK.

Summary

Materials and methods.

146 commercial tea products (73 CS and 73 herbal) representing 33 manufacturers, 17 countries, and 82 plant common names, were collected or purchased at 25 NYC locations. DNA was isolated and amlified for barcode-region rbcL and matK. Sequences of amplified products were used to search GenBank database using BLAST.

Results.

Most (90%) of tea products yielded rbcL or matK barcodes using a standard protocol.

Matching DNA identifications to listed ingredients was limited by incomplete databases, shared or nearly identical barcodes among some species, and lack of standard common names for plant species.

21/60 (35%) of herbal and 3/70 (4%) of CS teas generated DNA identifications not found on labels. Some of the surprise "ingredients" were plants used in tea, like chamomile, and some were common weeds or non-food plants, like lawn grass and goosefoot.

Significance.

Unlisted ingredients are common in herbal teas, demonstrating the importance of accessible plant barcoding. Broad-scale adoption may require character-based keys for distinguishing closely-related species.

Our results are published in Nature journal Scientific Reports

Stoeckle MY, Gamble CC, Kirpekar R, Young G, Ahmed S, Little DP. 2011. Commercial teas highlight plant DNA barcoding successes and challenges. Sci Reports 1:42

Our results attracted press interest

We followed in the footsteps of prior Trinity student DNA investigators.

• Kate Stoeckle and Louisa Strauss: "Sushi-gate"
• Matt Cost and Brenda Tan: "DNAHouse"

URL: http://phe.rockefeller.edu/barcode/teabol2011.html
Last updated: Wednesday, 22-Aug-2012 16:06:13 EDT