Friday, July 29, 2011

Teens Find Weeds in Tea

Combine science and tea and you have my immediate attention. Three teenage tea researchers used DNA testing to sleuth out the componants of one of the worlds' most popular beverage—tea. Mark me down as one of the more ardent tea fans.

Catherine Gamble, 18, Rohan Kirpekar, 18, and Grace Young, 15, tested commercially available teas using genetic analysis to find the DNA signatures of plants as part of the TeaBOL: Tea Barcode of Life Project. The young scientists tested 70 true teas (those that contain the leaves of the tea plant, Camellia sinensis). Of those, only a marginal 4 percent contained plants not listed on the labeling. However, the herbal infusions (tsanes) had unlisted plants in 21 of the 60 samples tested. In sum, 146 products from 33 different manufacturers were tested. The products came from 17 different countries.

Contamination in real teas is rare because they are cupped (taste tested) frequently. Unfortunately, the same can not be said for herbal infusions. This is a concern because of allergies and other health issues.

For example, a bag labeled "St. John's Wart" contained a type of fern. Those drinking herbal blends to avoid caffinee may want to look for a caffiene-free label; four of the "herbal" ifusions contained real tea leaves, Camellia sinensis, which naturally has a low level of caffiene.

Some of the other stow away plants found were:
  • chamomile (Matricaria recutita) – an herb
  • white goosefoot (Chenopodium album) – a common weed
  • red bartsia (Odontites vernus) – a common weed
  • bluegrass (Poa annua) – meadow grass
  • lantana (Lantana spp.) – a garden flower
  • Taiwanese cheesewood (Pittosporum pentandrum) – an ornamental tree
  • alfalfa (Medicago sativa) – a flowering grass
  • lemon balm (Melissa officinalis) – an herb
  • heal-all (Prunella vulgaris) – an herb
  • blackberry (Rubus spp.) – a fruit
  • papaya (Carica papaya) – a fruit

The young scientists also discovered unexpected genetic differences in teas from different areas. This surprising finding is exciting. The broad-leaf “assamica” tea exported from India and small-leaf “sinensis” variety tea exported from China, had new genetic differences scientists in this field of research had never seen.

How did the teens do it? They found high tech equipment for a low cost by purchasing used lab equipment on the internet for less than $5,000. They set up their genetic lab on the dining room table of their mentor, Mark Stoekle, adjunct faculty member with the Program for the Human Environment at Rockefeller University. Genetic samples extracted were sent for analysis at a commercial DNA sequencing facility.

You can read the full results of this tea study in the Nature journal Scientific Reports. Personally, I find this kind of involvement by teens in research to be not only exciting but also promising for the future of science.

Now, pardon me, but all this tea talk has made me thirsty. Time to go brew a cup of my favorite Chocolate Chip flavored black tea.

No comments:

Post a Comment