Thursday, April 19, 2018

Why does Earl Grey tea contain bergamot?

Have been lost in the weeds (or better said, tea leaves) putting together a course for World Tea Academy on blending teas with other flavor bearing elements. While I have been having a lot of fun discovering new ways of thinking about tea blending, a deadline looms...

But I can't resist telling you about Earl Grey tea. It's perhaps the most famous flavored tea in the West and traditionally combines a black tea with bergamot, either as peel or oil derived from the peel.

Image from Wikipedia, photo from the “Nürnbergischen Hesperidum - Volkamer”
by Johann Christoph - Nürnberg, 1714.
My exploration of Earl Grey tea led me to wonder: where did Lady Grey get the bergamot to add to the tea? Did she get it from Italy directly or from an orangery at her home, Howick Hall in Northumberland? (Orangeries were popular in 18th and 19th century noble houses—richly windowed buildings where the most exotic tropical and Mediterranean fruits could be grown successfully in frigid Northern climes.) This question led me to learn more about Howick Hall, built and rebuilt over the years starting in the 14th century.

Howick Hall, image from Wikipedia
While I still don't know whether Howick Hall had an orangery or not, I did learn that, of the many legends concerning the origins of Earl Grey tea's formulation, the one cited by the Howick Hall website is as follows: the addition of bergamot was suggested to the Earl by a Chinese envoy to counteract the lime (= calcium carbonate) content of the Hall's water. Water with a high lime content is more alkaline (higher pH) and of course has more calcium than pure water. 

It turns out that water high in calcium limits extraction of tea leaf compounds during brewing, leading to a tea with less caffeine and less amounts of polyphenols. This effect can be modulated by the acidity of the water, with greater acidity (lower pH) leading to greater extraction and less effect of the calcium. Bergamot's acidity would thus counteract this effect of calcium carbonate.

The other effects of calcium carbonate are on the extracted brew itself. As the tea cools down, "tea cream" develops—a turbidity that dulls the shine of the tea. Another problem is that the polyphenols continue to transform, yielding a more brown-orange and less red color. Look for this color change if you add milk to tea in a glass. Both of these transformations would make the tea less attractive to people who are used to a redder tea, with or without milk.

Black tea with and without milk—notice the color difference! Photo by Joanna Kosinska on Unsplash

But mostly, a lower pH yields a tea that simply tastes better.

Oh, and why bergamot instead of, say, lemon, which could accomplish the same goal?

I would imagine that it is because bergamot is more fragrant—and more exotic—than lemon. 

If you like your black tea better with lemon than without, now you know why.

==> Three Basic Teas & How to Enjoy Them, available in paperback and Kindle on Amazon!


Yong-Quan Xu, Chun Zou, Ying Gao, Jian-Xin Chen, Fang Wang, Gen-Sheng Chen, Jun-Feng Yin. Effect of the type of brewing water on the chemical composition, sensory quality and antioxidant capacity of Chinese teas. Food Chemistry, Volume 236, 2017, Pages 142-151, ISSN 0308-8146,

Chandini, S. K., Jaganmohan Rao, L. and Subramanian, R. (2011), Influence of extraction conditions on polyphenols content and cream constituents in black tea extracts. International Journal of Food Science & Technology, 46: 879-886. doi:10.1111/j.1365-2621.2011.02576.x

Wednesday, April 4, 2018

US League of Tea Growers and the aromas of tea

So excited about giving a talk via Skype about the development of tea aromas to the members of the US League of Tea Growers at their annual meeting in Mississippi. 

They will be hosted by Friend of Pairteas Jason McDonald of The Great Mississippi Tea Company. (Incidentally, their green tea won a silver medal among USA-grown teas at the Global Tea Championship last year, with a score of 93% in blind tasting!)

My talk will center around the aromas in teas and the processes by which they come into the cup. I'll emphasize time, temperature, and especially handling of the leaves as important for the development of the most delicious aromas. Here's one of the slides I prepared for the talk:

This slide shows compounds that emerge early in the processing of the tea leaves, and contribute to green tea flavor.

When a leaf is damaged, its cells immediately release hexanals—they give us the aroma of new-mown grass.

As injury and stress continue, leaves produce the three compounds in red—jasmonates, abscissic acid, and salicylic acid.  

Among its many functions, abcissic acid closes the stomata—the little "mouths"—on the underside of leaves that slow down water loss. You can easily imagine that large amounts of this compound are produced in the withering room! 

Notably, abscissic acid is also the precursor for the formation of nerolidol, the aroma compound that is the hallmark of high quality oolongs. The more punishment tea leaves experience when being transformed into oolongs, the more nerolidol is formed.*

Linalool and geraniol are normally stored as glycosides in the plant cell's central vacuole, far away from the enzymes that break up the glycosides. When the cell is damaged, the glycosides leak out of the central vacuole, come into contact with the enzymes, and the delicious cool rose-like aromas of linalool and geraniol waft in the air.

As for salicylic acid, it is the precursor for methyl salicylate. It takes time and a lot of processing for the leaf to form methyl salicylate, so you won't find it in green tea, only black. It is one of the compounds that give black tea is rich sweetness.

As for the green border around ß-ionone? As you may have seen me mention before, I can't smell this compound, and neither can some 40% of people of European descent. Pity, because people who can smell it say it smells delightfully floral!

Ying Zhou  et al. Formation of (E)-nerolidol in tea (Camellia sinensis) leaves exposed to multiple stresses during tea manufacturing. Food Chemistry 231 (2017) 78–86.

==>> Available on Amazon in paperback and Kindle: "Three Basic Teas & How to Enjoy Them."

Wednesday, March 28, 2018

Strawberries, a matcha roll, and Takashi Murakami

Last weekend, went to see for a second time the extraordinary exhibit at the Boston's Museum of Fine Arts, "Takashi Murakami: Lineage of Eccentrics" — Small, seemingly easy to encompass, but dives you deep into the question: what is art all about? Topic for another blogpost!

Oops! Forgot to write down what this painting by Murakami is called when I took the photo...
For this post, the question is: what about tea and food? After an hour+ contemplating dragons as people and people as dragons it was time to grab a snack, so went to the court at the center of the MFA, where my daughter and I shared a matcha strawberry roll, with fresh strawberries and white chocolate vanilla cream. My daughter and I also tried an iced green tea with ginger and mango.

We started with the fresh strawberries and white chocolate vanilla cream. Vanilla and strawberries both activate the warm receptors in your mouth and nose, while the fat from the white chocolate shuts down the hot receptors. The result is a noticeable enhancement of both the strawberry and the vanilla flavors.* While I am no fan of white chocolate on principle, this was a divine combination—one I will discuss in detail at World Tea Expo in June.

By contrast, the matcha roll itself had little to recommend it beyond its good looks, and the fact that its swirls echoed paintings in the exhibit:

Takashi Murakami, Dragon in Clouds—Red Mutation: The version I painted myself in annoyance after Professor Nobuo Tsuji told me, “Why don’t you paint something yourself for once?” Photo Evera Lovelace.
As I see it, the problem with matcha in baked goods is that its color and flavor don't survive the baking process. The bright green of matcha comes from intact chlorophyll. As I discuss in my book, "Three Basic Teas & How to Enjoy Them," when you heat chlorophyll the molecule loses the magnesium ion that gives it a bright green color, so the result runs from a dull green to an ashen grey, depending on further breakdown of the chlorophyll molecule.

Further, the other ingredients in baked goods dampen the brightness of the flavors of matcha, as they all tend to activate the warm and hot receptors at the expense of the cool and cold receptors activated by brewed matcha. And of course the sugar and salt both inhibit any bitterness. So you want to ask: what is the point of the matcha?

The strawberry cream in the middle was also very muted in flavor, whether because of a lack of strawberries in it, or because of its battle with the matcha cake.

By contrast, the iced ginger green tea with mango was a fascinating success, fascinating because when sipped alone, the mango (mixed in the drink as a puree) disappeared—mango activates warm receptors, where as both the ginger and the green tea, and of course the ice, activate cold receptors. Net effect, as my daughter described it: cool and refreshing!

However, with a bite of fresh strawberry, the mango became more pronounced, and the whole profile of the drink shifted. A great demonstration of the interactions among receptors, their activators and their suppressors, and a fitting complement to the shifting impressions that explorations of Murakami's art and its contexts bring.

Which brings me to another note: have been hard a work creating a new course for the World Tea Academy, this one about creating tea blends (such as this iced tea!).  It will be part of a series on blending teas that will include important information about regulations and methods for carrying out the blends by Scott Svihula and Brian Keating.

Hope you are having fun with your tea, too!

===> Available on Amazon in paperback and Kindle: "Three Basic Teas & How to Enjoy Them."

Wednesday, March 14, 2018

Wuyi oolongs: art and chemistry

Below, the introduction to the entrancing surrealist tea art of Julian Landa: photographs of the Wuyi mountains, transformed to remind us that Wuyi is where oolong originated—find the series at

Julian took the photos while on a pilgrimage to the Wuyi mountains with his wife, Cynthia Gold, renowned Tea Sommelier at L'Espalier in Boston (see my post of 2/7/18)  to experience first hand the extraordinary landscape and its famous teas.

To contemplate Julian's images, I brewed myself a Wuyi Rock oolong, Ma Tou Rou Gui from Horse Head Mountain via Verdant Tea ( Their website shows the fantastical rock formations and tea gardens captured by Landa's art—to me it was easier to imagine teapots in these mountains than horses' heads! 

The unbrewed leaves smelled slightly roasty and woody and offered a slight prickle in the nose. Nothing floral. The aroma of the brewed tea had the lovely full warm roasty wintergreen* characteristics of highly oxidized Wuyi mountain oolongs, but strangely no prickle. The flavor was also roasty and sweet, but after a slight delay you could sense the prickle in the throat that the smell of the dry leaf foretold. 

Here's the brew -- a dark oolong, quite roasty!

Verdant Tea describes this prickle as a "tingling cooling quality" that "seep[s] into the tongue after only a few sips and grow in intensity over each steeping." 

In the video on the webpage describing the tea, Li Xiangxi leads a class in Wuyi rock tea appreciation, where she calls the aftertaste "Yan Yun." She goes on to mention the aftertaste of Tie Guan Yin as "Yin Yun," and that of Tai Ping Hou Kui (a mind-blowing green tea that I will present to you in some other post) as "You Yan." **

Back to "Yan Yun:" Li Xiangxi states that, of the three aftertastes/resonances ("Yun"), Yan Yun is the most "opaque." She notes that the Emperor Qianlong described the "Yun" as "fish bones in his throat," a sensation that he apparently appreciated very much, despite the connotations. I sensed exactly what he meant when I tasted the tea. After a short beat, I felt this sharp though not unpleasant sensation in my throat that lingered for quite a while. 

Of course (being myself) I then asked what chemical compound(s) in the tea could cause this sensation? In order to answer this question, I first had to ask: is this sensation accompanied by hot (TRPV1 activation) or cold (TRPA1 activation)? Honestly I couldn't tell, though it did remind me of the catch in the throat that you get with a good olive oil, caused by activation of TRPA1 by oleocanthol. So I decided to carry out an experiment. 

I had just received a superb chocolate from Ben Rasmussen of Potomac Chocolates—the reward for having supported him in his Kickstarter campaign ( It was 70% Tumaco Columbia chocolate that tasted very warm and winey. If the chocolate cancelled out the catch in the throat, there would in all likelihood be a compound in the tea that activated TRPA1— chocolate has multiple compounds that would activate TRPV1 and turn off TRPA1. 

Here's the set-up half-way through the experiment, tea, wet leaves, and chocolate!

This experiment started me on the most exciting see-saw: first I tasted the tea, and got the catch in my throat, then tasted the chocolate—again a beat and the flavor of the chocolate filled my mouth and the catch disappeared, though I could still taste the roastiness of the tea. Then back to the tea and the catch came back, and then the chocolate and it this for several iterations.

I concluded that compounds in the tea activated TRPA1. 

So what could these compounds be? A paper published just this year provided the answer.*** It turns out that Wuyi rock teas have relatively large amounts of at least two distinctive compounds that activate TRPA1: quercetin and kaempferol.**** 

Below, graphs showing the quercetin and kaempferol content 14 Wuyi rock teas, from S Chen and colleagues. RG refers to Ruo Gui. As you can see, it does not have the highest amount of these compounds, but it has more than many.

Which raises the next question: why are these compounds present in higher levels in Wuyi rock teas, the only teas so far in my experience that give such a clear prickling sensation? Is it a question of "terroir?"

I don't know the answer to this question, but I present the following to support the "terroir" hypothesis, namely that the enzymes for the biosynthesis of these compounds require iron.***** Iron is abundant in the red sandstone of the eastern Wuyi mountains—it's what gives the rock of these mountains a slightly reddish hue, visible in Julian's photo/art above. 

Which brings me to another attribute given to Wuyi rock teas: minerality. The wine world has been discussing what people mean when a wine has minerality.****** According to Wendy Parr and her colleagues, minerality is characterized by a "fresh/zingy note." I have found that when people say "fresh" they refer to a cooling sensation, and when they say "zingy" the sensation is a kind of other words the effects you would get with activation of TRPA1. So it is likely that these compounds contribute to the minerality of Wuyi rock teas. 

Spent the day imagining a warm walk through Wuyi gazing up at the rock formations among clouds of tea, far away from the crisp cold snow here in Massachusetts. 

Hope you had a richly filled day, too!

===> On Amazon in paperback and Kindle: "Three Basic Teas & How to Enjoy Them"

* The wintergreen quality comes from the presence of methyl salicylate, which is produced as you roast tea.

** This video is well worth the watch. Li Xiangxi begins the tea tasting with hot water, declaring it sweet. Warmth activates TRPM5, the receptor/channel in taste bud cells that also transmits sweet sensations, so the brain interprets the experience as "sweet." She also talks about Western versus Chinese art, a vast topic, but one that I may poke at in a coming blogpost.

*** (Si Chen et al. Metabolite Profiling of 14 Wuyi Rock Tea Cultivars Using UPLC-QTOF MS and UPLC-QqQ MS Combined with Chemometrics. Molecules 2018, 23(2), 104; doi:10.3390/molecules23020104.)

**** (Toshiyuki Nakamura, Noriyuki Miyoshi, Takeshi Ishii, Miyu Nishikawa, Shinichi Ikushiro & Tatsuo Watanabe (2016) Activation of transient receptor potential ankyrin 1 by quercetin and its analogs, Bioscience, Biotechnology, and Biochemistry, 80:5, 949-954, DOI: 10.1080/09168451.2015.1132148)

***** Pengbao Shi et al. Foliar applications of iron promote flavonoids accumulation in grape berry of Vitis vinifera cv. Merlot grown in the iron deficiency soil. Food Chemistry
Volume 253, 1 July 2018, Pages 164-170.

****** Wendy V. Parr et al. Perceived minerality in Sauvignon wines: Influence of culture and perception mode. Food Quality and Preference 41 (2015) 121–132.

Sunday, March 4, 2018

Oolong aroma and taste: processing or variety and terroir?

Found a paper comparing five oolongs each from Yunnan and Fujian, and comparing these to samples of Chinese green, black and puer teas.* The focus of the paper was on the oolongs, to determine whether it was Camellia variety and terroir, or the processing that most affected the sensory qualities of the resulting tea.

The Yunnan oolongs were made from Camellia sinensis var. assamica and the Fujian oolongs from Camellia sinensis var. sinensis, all from the spring 2015 harvest. Here's a picture of the teas from the article:

The teas described in the article. The authors noted that the Yunnan oolong was paler than the Fujian oolong, consistent with differences in polyphenol content.

What fascinated me was that the aromas of the two different types of oolongs were very similar and their volatile chemistry (which provides for the teas’ aromas) were virtually identical. The aromas were significantly different from the aromas of the other teas. What these reslts suggest is that it is processing that influences the aromas these teas.

By contrast, the tastes of the two different kinds of oolongs were noticeabley different, with the Yunnan being less sweet and noticeably more bitter than the Fujian teas. 

I’ve graphed the concentratiions of epigallocatechin gallate (EGCG) and total polysaccharides: 

ECGC and polysaccharide content (in
mg/g) of Yunnan and Fujian oolongs. The differences in content are statistically significant.

What you notice is that the Fujian tea has more ECGC—the most bitter compound in an oolong. So why was the Fujian less bitter than the Yunnan? My guess is that the sweetness of the polysaccharides in the Fujian tea inhibits the perception of the bitterness. 

And the other important conclusion from this paper: terroir and/or variety influenced the polysaccharide content of the teas as well as the catechin content. 

Tea leaves produce catechins in response to sunlight—these chemicals act like sunscreen—so environmental conditons can be expected to make a difference in catechin content. In fact one of the consequences of global climate change has been a decrease in spring rains with the development of droughts in both Yunnan and Fujian provinces, a problem for first flush leaves.**

Friend of Pairteas Selena Ahmed and her colleagues have documented the effects of the increase in spring droughts in Yunnan on catechin content and sensory qualties of the region’s teas.*** With drought and increased sun exposure, catechin content of the teas increased over the past several years, and local tea famers have noticed both a decrease in the sensory quality of the teas and a decrease in the price they recieve for their teas.

* Wang Chen, Lv Shidong, Wu Yuanshuang, Gao Xuemei, Li Jiangbing, Zhang Wenrui, Meng Qingxiong. Oolong tea made from tea plants from different locations in Yunnan and Fujian, China showed similar aroma but different taste characteristics.  SpringerPlus (2016) 5:576 DOI10.1186/s40064-016-2229-y.

**Chen Huo-Po, Sun Jian-Qi. Drought Response to Air Temperature Change over China on the Centennial Scale. Atmospheric and Oceanic Science Letters, 8(3): 113-119. 

***Ahmed S, Stepp JR, Orians C, Griffin T, Matyas C, Robbat A, et al. (2014) Effects of Extreme Climate Events on Tea (Camellia sinensis) Functional Quality Validate Indigenous Farmer Knowledge and Sensory Preferences in Tropical China. PLoS ONE 9(10): e109126.'

Wednesday, February 7, 2018

Nepali Tea at the Sunday Tea Tasting

Sunday Tea Tasting at L'Espalier Boston orchestrated by Tea Sommelier Cynthia Gold and led by Nepali Tea Expert Jeni Dodd: a splendid experience, in part due to Jeni and her knowledge of Nepal and its teas, in part due to the teas themselves, in part to the enthusiastic and multi-talented company attending the tasting, and in part to the presentation of teas in glasses, like flights of wines.*

First saw the use of wine glasses with Kristin van Eetvelt's tea events, and find that it is a huge step in elevating tea as worthy of pairing with meals.  And the shining glasses looks so festive! 

Here's Jeni with Sunitra Joshi from Nepali Tea Traders presenting the Nepali tea experience. 

I particularly appreciated the white tea, called Himalayan Sunrise, from the Panchthar District in far Eastern Nepal on the border with India. Here's a map of Nepal, with this district circled in red. It's right next to India—Darjeeling is right across the border. 

Map from Wikipedia, circle added.

Here's what the leaves look like:

You can see the beautiful white hairs (trichomes). Each hair has a small globule of oil nestled at its base. Because white teas are withered without pan-firing, these globules remain intact, to release their delicious chemicals into your cup. (More about this phenomenon in my upcoming sequel to "There Basic Teas & How to Enjoy Them," where I will present all you might want to know about white teas.)

This particular white tea, from Camellia sinensis var. sinensis, yields a rather dark liquor, that has a nutty malty toasty aroma with a vegetal undertone, that to me was unexpected—I was anticipating a more floral flavor. This tea made me think of chestnuts. Am wondering whether these globules picked up chemicals from wood fires or some other source of roasted/burnt chemicals in the vicinity. 

Another remarkable tea was the Golden Tea, from Kanchanjunga Organic Tea in Illam, also from the Panchthar district of eastern Nepal. This tea estate was developed by a woman who first sold teas by the side of the road. She is busy turning her tea making skills into a major enterprise—look out for her! 

==>> Important: as Jeni noted, most small-garden orthodox tea from Nepal is organic, in that no fertilizers or pesticides are used, but the certification process is too expensive at this time for most growers. Here's a link to a story in Tea Journey about one of these growers:

This Golden Tea, a black tea, had a delightful golden color as its name would suggest, and a faintly cool fruit flavor, possibly the result of growing near kiwi fruit. What struck me, though, was its aftertaste, which was somewhat astringent, but filled my mouth with a pleasurable warmth. Cynthia paired this tea with a number of different small bites. To me it went best with a smoked Gouda eclair, which expanded this warm aftertaste.

In the picture below I am pontificating to Jeni about her talk. Actually I was praising her for the fact that she made 3 important points—any great talk always has 3 important points!
  1. Teas from Nepal are delicious and unexpectedly different from other teas, and should be enjoyed with foods just as we were doing at this event.
  2. Tea commerce is better than a handout for helping Nepal catch up economically with the rest of the world, especially after the devastating earthquake of 2015.
  3. The role of women in the development of tea commerce will be critical—they are going past simply being pickers to being tea exporters.

At least I think those were the 3 points I was I think about it, there were of course many more take-home messages. 

For example, she mentioned that until 1959, all the tea plantations belonged to the King of Nepal, but the first privately owned orthodox tea manufacture was only established in 1993, so it's early days for the development of Nepali teas. 

In the same time many plantings were no longer maintained and some trees grew wild. These wild trees give teas with distinctive flavors, such as Wild Sunset from Everest Tea in Sindhupalchowk, just south of Mount Everest. Here's a photo taken from the Everest plantation—it's only about 35 km. from Kathmandu, but it takes some 2 hours to get there!

Photo from the Facebook page of Everest Tea, Sindhupalchowk.
This black tea had a slightly cool flavor that comes from growing near eucalyptus trees, but which again gave way to a warm aftertaste more typical of a black tea. When first sipped, this tea was very mild, probably because of the competition between its cool- and warm-receptor activating compounds. However, when we tasted it with a bite of chocolate, its flavor came into full warm delicious bloom, with the eucalyptus very much gone. By contrast when we tasted it with an almond tea cake with jasmine citrus jam (all cool/cold/warm receptor activators that turn off the hot receptors activated by the tea), the tea simply disappeared—one could possibly argue for a slight eucalyptus hint, but that would be pushing it. 

To find out more about these teas and where to get them, Jeni says to contact her: jenis.tea[at]

And if you are in the Boston area, be sure to contact L'Espalier to find out when Cynthia Gold is holding her next tea tasting—or just go there for a superb meal accompanied by Cynthia's teas!

Virginia Utermohlen Lovelace MD

==>> "Three Basic Teas & How to Enjoy Them" — how flavor arrives in your cup and how you experience it! Available in paperback and Kindle on Amazon!
* Here's Cynthia Gold's secret to serving the teas in wine glasses: use [relatively thick] glasses with no bubbles in them, and they won't shatter, even when the tea being poured is at around 208ºF, just shy of boiling! 

Wednesday, January 31, 2018

Blended teas and drug/diet interactions

Have begun working on a course for the World Tea Academy on blending flowers, fruits, and more, into teas, including teas from both Camellia sinensis and rooibos. I think I will add hibiscus into the mix as well. 

The course is going to begin with a discussion of the classic English blend, Earl Grey, a combination of black tea with bergamot, so I have been looking into the chemistry of bergamot in more detail.

As you know, bergamot is a member of the citrus family, and its oil contains a host of chemicals that are common to many different kinds of citrus, grapefruit in particular. In fact an important chemical, bergamottin, gets its name from the bergamot, but is more abundant in grapefruit. It is one of a class of compounds called furanocoumarins.

The reason that bergamottin is important is that—together with 6',7' dihydrobergamottin, another chemical in bergamot and grapefruit—it inhibits an essential enzyme family involved in drug metabolism, called cytochrome P450.

The consequences of this inhibition are neither simple and nor predictable. For example, some medications are detoxified by cytochrome P450 enzyme in the gut and possibly the liver, so inhibition of these enzymes by bergamottin and similar compounds will increase the blood levels of the drug you get from a given dose. For some drugs the result is toxicity, which may be serious and even possibly life-threatening. However, for other drugs, inhibition of cytochrome P450 may mean that you could get the desired effect at a lower, less toxic dose.

Bergamot —Image from Wikipedia.
On the other hand, there are drugs that require metabolism by cytochrome P450 enzymes in order to be active. For these drugs, consumption of a cytochrome P450 inhibitor means you would actually have to increase your dosage for the drug to be effective. 

Look up "grapefruit juice effect" in Wikipedia to get an idea of what drugs are involved, as well as more information about the bergamottin/drug interactions.

Incidentally, there are other common additives to teas that may have the same effects, including angelica in particular.*

While I have not found reports associating reasonable amounts of Earl Grey tea with drug metabolism problems, you should be aware that these problems may exist, and not just with Earl Grey, but with other blended teas and herbal teas.** 

And always, consult your doctor about drug/diet interactions! 

* Guo LQ, Yamazoe Y. Inhibition of cytochrome P450 by furanocoumarins in grapefruit juice and herbal medicines. Acta Pharmacol Sin. 2004 Feb;25(2):129-36.

** Rainer Nowack, Barbara Nowak. Herbal teas interfere with cyclosporin levels in renal transplant patients. Nephrology Dialysis Transplantation, Volume 20, Issue 11, 1 November 2005, Pages 2554–2556.

Friday, January 26, 2018

How strong is the smell of new-mown grass to you?

When grass is cut, a chemical called leaf alcohol (chemically speaking 3-cis-hexen-1-ol or (Z)-3-hexenol) is released into the air. It's the plant's way of signaling that it has been injured. Tea leaves do the same thing. You're probably not surprised to find out, then, that the chemical is particularly prominent in green teas, but it's present in most other teas as well.*

According to The Good Scents Company, the taste (= flavor) of this chemical is "Fresh, green, raw, fruity with a pungent depth." In other words, it activates not just your odor receptors but also your cool/cold receptors, hence "fresh," "raw," and "pungent."

Turns out that to some people the smell of leaf alcohol is more intense than it is to others. People who are more sensitive tend to consume cucumbers a little more often, perhaps because for them cucumbers are more flavorful?** Here's the graph:

The difference looks slight, but it turns out that statistically it is quite significant.

The odor receptor for cis-3-hexen-1-ol is named OR2J3. Changes in the structure of this receptor lead to a 25% decrease in the ability to smell this chemical!***

There a single genetic change that is in strong linkage disequilibrium with these changes in OR2J3. Linkage disequilibrium means that if you have a version of the gene change in one place in your DNA, you are very likely to have a gene change in another location in your DNA. You can find this linked genetic change in your raw DNA report from both Ancestry DNA and 23andme, at rs7766902.

I've included rs7766902 in my survey on tea preferences and genetic changes. If you have done either 23andme or Ancestry DNA, would love to have you take the survey so we can find out whether a change in rs7766902 leads to preferences in tea just as it does for cucumbers!

Here's the link to the survey:

Be ready to take a few minutes to find your raw data, but I think finding out why you like what you like will be worth it!

Thanks so much --

* Chi-Tang Ho, Xin Zheng, Shiming Li. Tea aroma formation. Food Science and Human Wellness 4 (2015) 9–27.

** S.R. Jaeger, B. Pineau, C.M. Bava, K.R. Atkinson, J.F. McRae, L.G. Axten, S.L. Chheang, M.K. Beresfor*d, M. Peng, A.G. Paisley, H.C. Reinbach, S.A. Rouse, M.W. Wohlers, Y Jia, R.D. Newcomb. Investigation of the impact of sensitivity to cis-3-hexen-1-ol (green/grassy) on food acceptability and selection. Food Quality and Preference 24 (2012) 230–242.

*** Jeremy F. McRae, Joel D. Mainland, Sara R. Jaeger, Kaylin A. Adipietro, Hiroaki Matsunami, Richard D. Newcomb; Genetic Variation in the Odorant Receptor OR2J3 Is Associated with the Ability to Detect the “Grassy” Smelling Odor, cis-3-hexen-1-ol. Chemical Senses 37 (2012) 585–593.

Wednesday, January 17, 2018

Hot Tea Month Survey Time!

Is there a genetic basis for hot tea preferences? Have you had your DNA tested? If so, you can help us discover the answer!.

I've chosen three genetic markers—single nucleotide polymorphisms or snps—that may modify how we experience flavors and thus our tea choices.

For example, there is a single snp change that makes you unable to smell beta-ionone, a  floral chemical that's in all Camellia sinensis teas. I have this snp change, so I cannot smell beta-ionone. I've found that the aromas of teas are not quite so flowery to me as they are to other people—this may be why.

The other two snps in the survey are in genes that influence how many taste buds you have on your tongue, so the overall intensity of flavors for you, and how you experience the smell of cut grass—a smell that is typical of green teas. 

(Note that I'm not collecting any identifying information and no IP addresses, so the results I receive will be anonymous.)

==>> The following instructions are for 23andme and AncestryDNA. If you have done one of the other DNA tests, check to see whether they offer results for the snps listed below.

Before starting this survey, go to either 23andme or Ancestry DNA, and write down your results for the following so you can insert them in the survey:

     A. Your ethnicity (areas only—don't need percentages)

     B. The results for the following snps: 

  • rs227433 
  • rs6591536
  • rs7766902

Here's how to find your raw data concerning these snp's:

If you have completed 23andme:

  1. Click on “Tools” in the header of your page. 
  2. Scroll down to “Raw Data” and click on “Browse your data.” 
  3. You will see a box with “Search your data for a specific gene or marker (SNP)
  4. Type in the letter-number combinations (for example rs227433), then scroll down to find the letters entered under “Your genotype” in the table.

If you have completed Ancestry DNA:

  1. Click on “Settings” on the right hand side of your AncestryDNA homepage.
  2. On the right hand side, click on “Download Raw Data.”
  3. Once you have entered your password in the pop-up box, you’ll receive a confirmation email and download instructions at the email address associated with your Ancestry account. You will then be able to search for a specific DNA result (for example rs227433).

Now click here for the survey:

Once you have completed the survey, you will see "instant results" that show you how many people like each kind of tea, etc. 

Once I have collected data from 100 people, I will be able to tell you whether there are any relationships among the results, in other words whether the snps have anything to do with tea preferences, and I'll let you know!

Thank you so much for participating!