Why Fingerprinting Tea Is a Good Idea

There’s long been some suspicion about whether all “Darjeeling Tea” is really from Darjeeling. After all, Nepal tea gardens are a short hop from Darjeeling and if they are blended or substituted, how many of us would know—especially when we assume our tea is what the label claims?

For tea gardens that produce high-quality tea, this is a problem.

Darjeeling banks on its name, for instance, having been awarded the first geographical indication of India, meaning that its quality is attributable to its geographic origin. Likewise, Assam’s unique environment contributes to its tea’s maltiness, pu’erh’s prestige hinges on its Yunnan province (China) origin, and so on.

989 all three crop for blog
Assam teas

When tea is misrepresented or inferior tea mixed in, reputation suffers. In Indonesia, the Chamber of Commerce and Industry is asking for a higher import tax on tea because it’s common for imported poor-quality tea to be mixed into Indonesian-grown high-quality tea. This of course reduces the overall quality and drives down the price!

Tea-leafTo combat the possibility of tea being sold as something it’s not, scientists have been developing tools to trace and authenticate specific teas.

This isn’t easy, especially because we still don’t know the entire genomic sequence of Camellia sinensis, and there are thousands of varieties—each with their own properties that affect tea quality—being grown around the world. Complicated further by the processing that tea undergoes, along with a lack of data standardization, this isn’t a straightforward path.

Several tactics are being developed, and newly emerging data are encouraging.

  • A 2014 pilot study (W-P. Fang et al.) was promising, having:

demonstrated a DNA fingerprinting method that uses a small set of SNP [single nucleotide polymorphism] markers to verify the genetic identity of a single bud or leaf. This method can handle a large amount of samples in a short period of time and the result is highly robust and repeatable.

  • Newly published research focused on identifying the geographic origins of green teas, using markers that included catechins and phospholipids (Navratilova 2019). Preliminary results distinguished between tea that originated from China, Japan, and South Korea.
  • Another recent study used trace elements rather than bioactive compounds, thus circumventing the effects that production processes have on tea. According to the authors:

Since the minerals and nutrients present in plants may be representative of the composition of the surrounding soil, plants grown in the same area tend to have their own characteristic elemental fingerprint. (Nelson and Hopfer 2018)

Initial findings were encouraging, with further research ongoing.

  • Tea growers in Scotland are particularly anxious to be able to prove that their tea is actually grown in-country, as a single-origin tea, because the UK brand of “Scottish Breakfast Tea” does not contain tea that is grown in Scotland.

On a side note, this type of labeling complicates the entire issue. As another example, although Russian Breakfast and Irish Breakfast tea blends are identified with those countries, the tea itself is not grown in Russia or Ireland.

Anyway, the University of Aberdeen and the Scottish Tea Factory teamed up, comparing trace elements of tea grown in Scotland with imported tea of known origin. As reported in the World Tea News (Burslem and Wainwright 2019):

The results show a promising differentiation of the chemical signature of teas of authentic Scottish origin, possibly reflecting the distinctive background composition of soils in Scotland compared to the traditional tea-growing regions of Africa and Asia.

We can expect such research to continue as reputable gardens and companies seek to protect their name and to assure profits for tea that’s worthy of its price. Sure, many of us may never be able to discern that one tea has been substituted for another, but that’s really beside the point. It’s integrity. And sometimes you have to fight for that, prove that consumer trust is well placed.

Additionally, such studies also take the pulse of the gardens, helping guide plant management and breeding. As the earth’s climate continues to change, these tools may prove worthy of the time, commitment, and research dollars that went into them. The more we know about which varieties thrive in which environments, the better equipped we are to match variety to new growing circumstances—and keep tea a part of the daily routine for future generations.

Oolong from Nepal: Finest Nepal Hand Rolled Jun Chiyabari

Sources:
–”Authentication of specialty tea: an application note,” by J. Nelson and H. Hopfer, Food Quality and Safety, 12/6/18, https://www.foodqualityandsafety.com/article/specialty-tea-authentication/2/?singlepage=1.
–”Green tea: authentication of geographic origin based on UHPLC-HRMS fingerprints,” by K. Navratilova et al., Journal of Food Composition and Analysis 78 (May 2019):121–28, https://www.sciencedirect.com/science/article/pii/S0889157518311505?via%3Dihub.
–”Kadin calls for review of tea import tax tariff,” Antara News, 3/14/19, https://en.antaranews.com/news/122673/kadin-calls-for-review-of-tea-import-tax-tariff.
–”University of Aberdeen study covers tea authentication,” by D. Burslem and B. Wainwright, World Tea News, 3/11/19, https://worldteanews.com/editors-choice/university-of-aberdeen-study-covers-tea-authentication.
–”Varietal identification of tea (Camellia sinensis) using nanofluidic array of single nucleotide polymorphism (SNP) markers,” by W-P. Fang et al., Horticulture Research 1 (2014):14035, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4596320.

Teas shown here are available at TeaHaus.

12 thoughts on “Why Fingerprinting Tea Is a Good Idea

  1. I believe in Taiwan, there was also a case where Vietnamese oolong was being passed off as Taiwanese oolong and marked up several times! I remember that case because my company (teapasar) is also working in the tea authentication sphere – we’ve been getting really good results using metabolomics (we can differentiate teas from different regions within a country and predict the taste of the tea) and it doesn’t cost that much either.

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    1. I imagine that tea swapping might occur more often than we think. From the research studies that I looked at, mostly preliminary work, it didn’t seem as though the technology was quite ready for widespread real-life application, but it looks like Teapasar has successfully implemented this idea. Really interesting! Does Teapasar also test for contaminants (e.g., heavy metal and pesticide residue)? I would think that that would also help trace tea because researchers probably have a good idea of what regions use what pesticides, or where regions have been contaminated. This entire topic is fascinating.

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      1. So far, we’re only testing for authenticity – we did look into testing for contaminants, but couldn’t detect them at the levels required by the authorities. Although if our tech continues to improve, we might look into whether we can identify suspicious teas that would need further testing.

        Yes, I agree it’s a fascinating topic! I heard of people using blockchain for authentication as well, but that doesn’t guarantee the same tea reaches the buyer, just that the box is the same. We’re hoping our method can provide more assurance that the tea that leaves the farm is the tea that reaches the consumer.

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      2. Re: tea-swapping, I’ve just thought of another case – matcha in certain countries is likely to be fake (if you define matcha as being from Japan and made in a set way) because of import restrictions. But that’s not very widely known (or at least, it was news to me when I found out!)

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        1. Definitely true. I briefly addressed that in one of my posts. Very little of what is called “matcha” here is actually matcha (made from tencha). From what I see on Reddit, many people don’t want to pay the price that true matcha commands, so they are essentially just getting powdered green tea. And of course all those “matcha” cookies etc. are unlikely to be real matcha. I think in the U.S. that many equate powdered green tea with matcha and truly don’t know there is a difference. Education is key! Along with authentication.

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  2. This is a FASCINATING post – thank you for writing it! Eustacia mentions Taiwanese research. Currently there is an effort underway there to map the isotopes patterns of different growing areas (e.g. Alishan, Shan lin Xi, Dong Ding etc) in order to authenticate specific region of origin (currently this is only possible at the countrywide level – e.g. Taiwan vs. Vietnam) I was fortunate to have been able to participate in a sample collection survey last November. This is not DNA research but an examination for isotope patterns. I look forward to seeing the results.

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    1. Thanks for filling us all in on this ongoing research (and how fun to be a part of it). It’s interesting to me how a question/problem can be approached in many different ways, and I appreciate the tenacity, dedication, and patience required of researchers to tackle these projects. A lot of work and time goes into these studies, and sometimes definitive answers are elusive. I hope that you will share the results of this work with us!

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  3. I recall a study from several years ago that used DNA barcode technology to show that a great deal of camellia tea is cut with various herbs such as parsley. If I can find the reference I’ll pass it on. Thanks for the interesting article!

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    1. I would be interested in reading that study—thanks! Although adulteration is nothing new (in the mid-1800s Robert Fortune described how a Prussion blue–gypsum powder was used to color green tea to make it “uniform and pretty” so it’d command higher prices from the Europeans and Americans) it’s sad to think it’s still going on and the consumer is unaware!

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