Tuesday, June 5, 2018

A delicious tea pairing: Lapsang Souchong and cheddar cheese

Sara got together with her friends Georgia and Gee again, the time to try out pairings of black teas with tea sandwiches, and as before the results are fascinating! 

Here are their blog websites:
Sara: http://www.tea-happiness.com/2018/05/tea-pairing-101-black-tea-and-tea-sandwiches.html#more
Georgia: https://www.notesontea.com/2018/05/tea-pairing-101-black-tea.html
Jee: https://www.ohhowcivilized.com/tea-pairing-101-black-tea/ 


...and here are the teas and the sandwiches, from Sara's blog http://www.tea-happiness.com/2018/05/tea-pairing-101-black-tea-and-tea-sandwiches.html#more

The three black teas chosen were about as different as possible! In this post, I'll talk about the first tea, an atypical Lapsang Souchong. 

What makes Lapsang Souchong different from other WuYi teas is that it is smoked over a pinewood fire. When carried to completion, the tea leaf's chemicals are replaced with ones from the burning pine wood. However I gather that the particular Lapsang Souchong that Sara, Georgia and Jee chose was less smoked, so retains some of the original black tea flavors that the Joseph Wesley Tea company (source of the tea) characterizes as "malty plum and chocolate."

Sara waxed enthusiastic about pairing this tea with a cheddar cheese sandwich with Branston pickle on whole wheat bread, and Georgia and Jee concurred. 

Before I go into why this combo works so well, a word about Branston pickle for those of us on this side of "The Pond." Branston pickle is a form of sweet/sour chutney made with dried chopped up vegetables (especially cauliflower and rutabaga), vinegar, tomato, lemon, apple, and spices, including mustard.* It is the classic accompaniment for cheddar cheese—when I had my first ploughman's lunch in England I went gaga over this combination!

So why then does the trio of Lapsang Souchong, cheddar, and Branston pickle work so well?

I like to think that it's because these three play with your hot and cold receptors in a fascinating, not to say dazzling, way.

First to the cool/cold receptors: 

As we will see below, most of the characteristic compounds of aged cheddar cheese activate the warm and hot receptors. However, Sara mentions that the cheese was "tangy," an effect that comes from activation of TRPA1, the cold receptor. Which chemical in the cheddar does this I don't know, but amazingly, this cheese has a large amount of linalool, a characteristic compound of tea that activates the cool/cold receptors. 

Next, the major compounds in pine smoke (and therefore in this tea), such as alpha-pinene and alpha-terpineol, also activate the cool/cold receptors—when you walk through a pine woods you can feel the coolness from these chemicals activating the same receptors in your skin as you have in your mouth. 

Finally, cauliflower, rutabaga (aka swede), and mustard—and in fact all the Brassicas—are characterized by chemicals that activate the cold receptor TRPA1. And the apple and lemon juice in the Branston pickle are both on the cool/cold side, too.

Summing up the cool/cold side of the equation: all the elements of this pairing activate the cool/cold receptors, so amp up the volume of all these flavors together. 

So what about the hot receptors? How do they come into play?

Both tea and cheddar have several chemicals in common that activate the warm and especially the hot receptors, including (believe it or not!) the characteristic volatile from damask roses that I talked about in my previous blogpost: beta-damascenone.** 

As Sara, Jee, and Georgia all noted, the cheddar also had a nutty flavor. This flavor comes from chemicals called pyrazines, that are present in the tea as well as the cheddar. As you might guess from their name ("pyr-" means "fire" in Greek—think of a "pyre") these chemicals are formed via Maillard reactions at temperatures at and above 100ºC (=boiling water temperature). And of course the Branston pickle was boiled as well—it's brown color comes from Maillard reactions. And by the way, good quality whole wheat bread is especially rich in Maillard browning products, too—that's why it tastes nutty.

So all in all there are a number of compounds in this pairing that will activate the warm/hot end of the temperature spectrum.

Which now brings me to the question of balance: there are three compounds in this combination that (I believe) serve to harmonize the combination of tea and sandwich successfully. These are vinegar, sugar, and fat. You'll notice that all these are responsible for tastes, and it's the interactions of these tastes with the temperature sensations via the trigeminal nerve (responsible for hot and cold) that may bring together this pairing.

Vinegar is sour, which is to say that it will activate receptors for sour in taste buds. At sufficient concentrations it will also activate the hot receptor TRPV1—you may have felt the burning sensation when you taste a vinaigrette. However, the same amount of vinegar when combined with oil will not cause a burning sensation because the fat turns off TRPV1. You will simply get the sourness. Then add some sugar to the mix, and even the sourness is tamped. 

In the case of this pairing, the fat to dampen the hot receptors comes from the cheese—cheddar has a high fat content—and the sugars to decrease the sourness come from the pickle and the bread. The net effect is to shift the overall flavor profile to the cool/cold side when you first bite into the sandwich and sip the tea. Then if you wait a short while, the cool/cold effect dissipates and there is a warm afterglow because the hot receptor, with its slow-on slow-off response, remains activated after you have swallowed food and drink. Re-sip the tea and take a bite of sandwich, and the whole process starts over again. 

As Sara said:

"It's a lovely pairing, so easy to eat that I could have it every week and not get tired of it."

An aside: my first taste of Lapsang Souchong when I was a young girl, was accompanied by cheddar and a slice of apple...so delicious, and now I know why!

* Data from https://en.wikipedia.org/wiki/Branston_(brand). For more about the pickle, see https://bringoutthebranston.co.uk/range/pickle/.

** T.K. Singh, M.A. Drake, and K.R. Cadwallader. Flavor of Cheddar Cheese: a Chemical and Sensory Perspective. Comprehensive Reviews in Food Science and Food Safety. Vol. 2, pages 166-189, 2003.

























Wednesday, May 30, 2018

Damask roses and black tea

So excited to be going to World Tea Expo, where I hope to carry out an experiment!

Damask rose. Image from Wikimedia Commons.

One of the characteristic chemicals in black tea is β-damascenone, a member of the category of chemicals called rose ketone, because it is characteristic of roses—damask roses in particular, as you can guess from the name.*


β-damascenone
According to William Luebke, this chemical has a "natural sweet fruity rose plumr grape raspberry sugar" odor, while according to Gerard Mosciano it has a "Woody, sweet, fruity, earthy with green floral nuances" odor.** To me it has a warm, sweet, deep, rich, dusty-rose odor reminding of the women's powders of my youth.

Turns out that the smell of β-damascenone is significantly more intense to some people that others.  This difference has been attributed primarily to a single nucleotide difference rs2220004.*** Unfortunately, neither 23andme nor Ancestry DNA report results for this snp, so I can't tell you whether my impression is the one attributed to the ability to smell the compound.

However, I do not "get" the green or the woody or the earthy, so perhaps I only sense part of the aroma, even at the high concentrations at which I sniffed it just now. According to McRae and his colleagues, about 1 in 10 people of European descent have the version of the snp that is less able to smell the compound. That said, β-damascenone appears to activate a number of different odor receptors, and it may be that a change in one of these receptors can alter the perception profile of the odorant without changing its perceived intensity.

At WTE I'm planning to go around with a small vial of β-damascenone and have people tell me what they smell, and see whether people do in fact describe it differently.

So exciting!

* The damask rose is one of the "Old Roses"—early hybrids whose origins and cultivation histories are the subject of much speculation. Genetic data suggest that the damask rose developed in Central Asia, but when it was brought to the Middle East and Europe is unknown. It probably gets its name from Damascus in Syria, which was under siege during the second crusade in 1148. Crusaders may have then brought the rose back to France and given it its name, though the plant was known in Europe before then. Damask roses are the major source of rose oils, rose water, and rose sugar, known as golab, and in other sweet dishes, an ingredient in ras al hanout, and in a number of  culinary delights from the Middle East, India, and Central Asia.

** As reported in the Good Scents Company website: http://www.thegoodscentscompany.com/data/rw1021911.html#toorgano

*** Jeremy F. McRae, Sara R. Jaeger, Christina M. Bava, Michelle K. Beresford, Denise Hunter, Yilin Jia, Sok Leang Chheang, David Jin, Mei Peng, Joanna C. Gamble, Kelly R. Atkinson, Lauren G. Axten, Amy G. Paisley, Liam Williams, Leah Tooman, Benedicte Pineau, Simon A. Rouse, Richard D. Newcomb. Identification of Regions Associated with Variation in Sensitivity to Food-Related Odors in the Human Genome. Current Biology, Volume 23, Issue 16, 2013, Pages 1596-1600, ISSN 0960-9822, https://doi.org/10.1016/j.cub.2013.07.031.

Thursday, May 17, 2018

Indian green tea

After a successful tasting experience at the Foundation Kitchen the other day, have been trying out the teas for my Skill Building Workshop "Learn to Pair Teas & Build Menus from Scratch."
https://www.worldteaexpo.com/wte18/Public/SessionDetails.aspx?FromPage=Sessions.aspx&SessionID=1020043&SessionDateID=1001192

Today I turned my attention to the green tea we are offering: Yatra Tea's Fatikcherra Estate, Tripura, Autumn Flush 2017.
After our tasting at the Foundation Kitchen.
For more about this ever so useful space for food start-ups in Somerville MA, go to https://foundationkitchen.com

Tripura is a tiny land-locked state of Northeast India, bordered on three sides by Bangladesh, and by the Indian states Assam and Mizoram to the East. It is impoverished, but at the same time it has an extraordinary literacy rate according to Wikipedia—about 95%. In other words, it has huge human potential, but because transport in and out of the state is so difficult, economic growth is slow.

The marker points to a school in Fatikcherra. I added the approximate Eastern border of Tripura to the Google map because it is very faint in the original. As you can see Tripura is in a difficult geographic position when it comes to economic development.

That said, tea is one of Tripura's two main cash crops, the other being natural rubber.

This green tea is organically produced, and GSFTFOP1, in other words high quality. The use of assamica leaves gives the tea a slightly malty as well as a vegetal taste. Furthermore it is autumn flush, harvested right after the monsoons, so a quite dark green/brown color (doesn't show up well in the photo below, but you can see the liquor is light colored).  Because the leaves have abundant catechins (catechins act as a sunscreen) the tea is somewhat bitter/astringent, but paired with the right foods (or a tiny tiny tiny bit of salt) its herbaceous qualities come to the fore, and to my mind it is delicious. It's not really anything like a Chinese or Japanese green tea, but I think it will be a lot of fun to taste and try with foods.

Here's my test brew, at 165ºF for 1.5 minutes.
I will reveal the results of our pairing tests at World Tea Expo, but if you can't go to the event, I'll be posting about it here in late June/early July, after I get back from Las Vegas plus a short vacation with grandchildren.

Meanwhile, here is a video from Fatikcherra—Ganesh dance—watch for the "elephant" at the end:
https://www.youtube.com/watch?v=XKxNgssEBcg

(Incidentally, World Tea Expo is less than a month away!)

=>>> Have made minor revisions/corrections to "Three Basic Teas & How to Enjoy Them." The book will be available again on Amazon by May 23rd.

Thursday, April 26, 2018

Green tea catechins and liver damage

A report* about possible toxicity for the liver of green tea catechins at high doses has raised concerns among Friends of Pairteas, so I looked into the matter this week.

In the US green tea catechins are available over the counter as supplements. Drugs considered dietary supplements are not regulated in the US in any significant way for either safety, effectiveness, or dosage limits. 

Epigallocatechin gallate (EGCG), the major catechin in green tea. Image from Wikipedia.

A major problem in determining whether green tea extracts have any effect, either beneficial or adverse: people differ tremendously in how much catechin a person absorbs from a given dose of supplement (or brewed green tea, for that matter). One person may have up to 6 times more catechins in their blood than the next person with a given dosage!**

The reason for this huge difference may lie, at least in part, in genetic differences in a person's capacity to transport drugs and the products of their metabolism for excretion in the liver and kidney. When certain drugs fail to be cleared from cells due to transport problems they can damage mitochondria, and ultimately lead to cell death. This phenomenon may explain why catechins, which are metabolized and excreted by the liver, may cause liver damage.

The question is then: how much catechin is needed to cause damage? and how severe is that damage? and one more question: do catechins interact with other drugs/suplements?

We don't know the answers to any of these questions. 

The European white paper stems from a spate of case reports and animal studies that have suggested that liver damage with catechin supplements may occur. In the case of animals, huge doses were delivered over multiple years, so these studies should not be extrapolated to humans. 

With respect to humans, one study of case reports that really scared me concerned a supplement called Slimquick®, where a person had to have a liver transplant.*** 

But case reports are problematic because you can't exclude the possibility that other issues, such as disease, the use of other medications or supplements, or even the purity of the catechin supplements, aren't the real cause of problems. 

These are the reasons why Isomura and colleagues decided to review human randomized control trials of catechins.**** In these trials, catechin supplementation was compared directly with placebo or no treatment, so that one could decide with some degree of certainty that the catechins were responsible for any adverse effects. 

Of the 34 usable trials reviewed by Isomura and colleagues, liver-related adverse effects were found in only four. There were 8 adverse events among the people received catechins and one event in a person receiving a placebo.

Of these four trials with adverse effects, only one involved healthy volunteers. Of the others, one involved women with breast cancer, one men with prostate cancer, and the third post-menopausal women who may have taken other medications. In other words, we cannot say whether any of the condition in these three trials may have contributed to the adverse events. 

Furthermore, adverse events in these trials consisted of elevation of liver enzymes, but no active disease. That said, elevation of liver enzymes are indeed an indication of active liver damage. The liver happens to have a rather large, though not infinite, capacity to experience damage without long-term consequences. 

Bottom line: we really don't know at this point whether catechin supplements cause liver damage, to whom, and at what dose. But the amounts in your favorite cup of green tea come nowhere close to the amounts in supplements. 

My advice: enjoy your green tea as a drink in a cup for its taste and avoid "magical" supplements that promise life-changing effects. Liver disease would indeed be life-changing!

Incidentally, Cornell University hosts a National Institutes of Health database where you can look at the toxic effects of different drugs and supplements on the liver:
https://livertox-nlm-nih-gov.proxy.library.cornell.edu

Longing tea steeping in a gaiwan. Image from Wikipedia.

* EFSA ANS Panel (EFSA Panel on Food Additives and Nutrient Sources added to Food), Younes M, Aggett P, Aguilar F, Crebelli R, Dusemund B, Filipič M, Frutos MJ, Galtier P, Gott D, Gundert‐Remy U, Lambré C, Leblanc J‐C, Lillegaard IT, Moldeus P, Mortensen A, Oskarsson A, Stankovic I, Waalkens‐Berendsen I, Woutersen RA, Andrade RJ, Fortes C, Mosesso P, Restani P, Arcella D, Pizzo F, Smeraldi C and Wright M, 2018. Scientific Opinion on the safety of green tea catechins. EFSA Journal 2018;16(4):523. 9, 89 pp. https://doi.org/10.2903/j.efsa.2018.5239

** Scholl C, Lepper A, Lehr T, et al. Population nutrikinetics of green tea extract. Atkin SL, ed. PLoS ONE. 2018;13(2):e0193074. doi:10.1371/journal.pone.0193074.

*** Zheng, E.X., Rossi, S., Fontana, R.J. et al. Risk of Liver Injury Associated with Green Tea Extract in SLIMQUICK® Weight Loss Products: Results from the DILIN Prospective StudyDrug Saf (2016) 39: 749. https://doi-org.proxy.library.cornell.edu/10.1007/s40264-016-0428-7

**** Isomura T, Suzuki S, Origasa H, et al. Liver-related safety assessment of green tea extracts in humans: a systematic review of randomized controlled trials. European Journal of Clinical Nutrition. 2016;70(11):1221-1229. doi:10.1038/ejcn.2016.78.



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!

References:

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, https://doi.org/10.1016/j.foodchem.2016.11.110.

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" — http://www.mfa.org/exhibitions/takashi-murakami. 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 http://www.julianlanda.com/new-gallery/.




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 (http://verdanttea.com/teas/horse-head-mountain-ma-tou-rou-gui-wuyi-oolong/). 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 (https://www.potomacchocolate.com). 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 disappeared...like 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 prickle...in 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.

*** http://www.mdpi.com/1420-3049/23/2/104 (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.)

**** https://www.tandfonline.com/doi/full/10.1080/09168451.2015.1132148. (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. https://doi.org/10.1371/journal.pone.0109126'