Sunday, April 29, 2007

The Basic Science of GABA | 2007 Spring GABA Oolong

An Introduction to GABA

GABA StructureGamma-aminobutryic acid (GABA) is the main inhibitory neurotransmitter in the brain. A neurotransmitter is essentially a molecule that one neuron sends to an adjacent neuron in order to excite or inhibit it from sending a signal. While GABA is the main inhibitory neurotransmitter in the brain, glutamate is the main excitatory one. Glutamate and GABA compete, in a way, to drive neurons to be more or less active. In general, altering glutamate or GABA levels in the brain can have global effects on the organism. A drop in GABA level or an increase in glutamate level, for instance, can cause seizures; likewise, a drop in glutamate level or an increase in GABA level can cause drowsiness or even coma.

Glutamate Structure***Related tangent: Fortunately, it is very difficult to disturb amino acid neurotransmitter levels to this extent, partly because of the blood-brain barrier. This is just what it sounds like: it keeps bad things out of the brain. Glutamate is actually the least likely amino acid to cross the blood-brain barrier into the nervous system, which could be an evolutionary reason for its adoption as the main excitatory neurotransmitter in the brain. This is important, because if the primary excitatory amino acid could cross this barrier, our brains would work themselves to death with each meal we ate. Needless to say, this would be very, very bad.***

I will talk a bit more about GABA later, but for now, here's a review:

2007 Spring GABA (Jia Yeh) Oolong from Hou De Asian Art

Class: Oolong
Origin: Zhu Shan, Nan Tou, Taiwan
Year: 2007
Vendor: Hou De Asian Art
Price: $12.50 (2oz)

This was an interesting experience, to say the least. No, I did not notice any relaxing or sedative effects beyond those I normally feel after drinking tea, but this tea is not all novelty, as it has some interesting and potentially enjoyable gastronomic properties.

First, some quick background. As I have mentioned once or twice before on Tea Nerd, nitrogen flushing is a good preservative for tea, as it displaces oxygen and slows down the post-production oxidation process. In Japan, in 1986, it was accidentally found that exposing raw tea leaves to an anaerobic (no oxygen), nitrogen-rich environment caused the concentration of GABA inside the leaves to increase, and thus the creative term "GABA tea" was coined. The Japanese apparently developed a fondness for the beverage, and Taiwan began tweaking its method of production to increase GABA content and improve flavor. GABA oolong has since become one of Taiwan's major exports, according to Hou De.

GABA Oolong Dry LeafThe dry leaf, as the Hou De product page describes, has a strong mango and guava fragrance. I also thought I picked up a bit of peach, but it's hard to say when there are so many different fruit aromas simultaneously assaulting my brain. Actually, the fruit fragrance was SO powerful that it was a little overwhelming (in a not-so-great way) and made this tea's nose fairly unbalanced.

As for looks, you can see from the picture that they are nice little rolled-up balls, which is pretty standard for Taiwanese teas. There is very little green here—most of the leaves are shades of tans and browns.

GABA Oolong LiquorThe liquor brews to a nice light brown, which I have tried to capture here. It smells very similar to the dry leaf, and tastes like it smells. There are strong mango and guava flavors, a nice sweet aftertaste, and a smooth feel especially in earlier infusions (interestingly, some of the earlier infusions taste similar to sweeter second flush Darjeelings). A bit of an artificial taste comes out in the later infusions. Overall there is not much that tastes bad about this tea, but I don't think the flavors are well balanced, as the fruitiness dominates completely. One more thing that I noticed here was that the tea had a long-lasting drying effect, but in the absence of anything I would normally call astringency. It was odd, and felt like I was eating flour. I'm a bit weird and actually enjoy eating flour, so this wasn't a bad thing in my opinion.

The wet leaves didn't smell all that different from the dry leaves, although I swear I caught a slight whiff of menthol or camphor (nothing like what can be found in puerh, though). It is a very pleasant aroma—definitely enjoyable.

GABA Oolong Wet LeafThen I dug into the leaf pile. The leaves are still attached to their stems, for the most part, which is a sign of hand-picking. However, it was fairly stemmy and sometimes I noticed that the 3rd and 4th leaves were attached to the stem in addition to the standard 2 and a bud. I could be wrong (please correct me if I am), but I have read that the lower leaves are of inferior quality. Still, as Salsero has reminded me, it's more about the taste than the little nitpicky things.

Overall, I thought it tasted quite decent. Maybe not incredibly complex, but certainly drinkable. Personally I would have enjoyed this tea far more if it were not for the unbalanced flavor profile, but if you are looking for an intensely fruity unflavored tea, this is the one for you.

The gabber about GABA

Back to the biology behind GABA (woo hoo!). Earlier, I mentioned that altering GABA and glutamate levels in the brain can have generalized effects on the overall activity of the brain, and GABA tea works on this principle-- more GABA = more inhibition. However, a far more common (and effective) method of altering GABA's activity in the brain is to modify its receptors' function.

***Yet another related, but important, tangent: The most important thing to know about neurotransmitters is that they do NOT produce their biological effect in the absence of their functioning receptors. A good analogy is to think of neurotransmitters as keys, and receptors as locks. GABA-A Ionotropic Receptor DiagramIf you have a key, it won't open any door without a matching lock it can fit into. Neurotransmitters are the same way— GABA, for instance, just binds to a receptor, but for the most part, the receptor protein is what effects the cellular changes in the cell it is attached to.***

You all know of chemicals that increase the activity of GABA receptors/ion channels (I won't go into the details of how ion channels work in neurons, but you can google or wikipedia it if you like), though you might not know that this is how they work. The most common examples are alcohol (ethanol, to be specific) and benzodiazapines (such as Valium), but there are many more. These molecules cause the GABA receptors to produce stronger effects in the cells they are attached to, and thus bring about a relaxing, drowsy sensation.

While we're on the subject, L-theanine is also known to affect the GABA system, though in a different way. While ingesting GABA is not a very effective method of increasing GABA levels in the brain, L-theanine causes the brain to produce more GABA itself. This is much more effective and is the reason why tea does not give as harsh a caffeine buzz as coffee. I'm thinking of doing a more in-depth post about L-theanine later, so keep your eyes peeled.


Though GABA tea does seem to have mild effects on the GABA system in the brain, it is not nearly as potent as some other substances due to its inefficient method of action (it probably takes the single most difficult path to the brain). So, you won't get sleepy by drinking it, but it's still kinda cool. Now, make sure you remember all of this&mdash it will be on the test.

Saturday, April 21, 2007

2005 Wuyi Bai Nian Lao Cong Shui Xian

Class: Oolong
Origin: Wuyi Mountain, Fujian Province, China
Year: 2005
Vendor: Jing Tea Shop
Price: $15.60 (100g) / $5.20 (25g sample)
Verdict: 9/10

Jing Tea Shop's Wuyi Bai Nian Lao Cong Shui Xian is probably my favorite of the 8 wuyi oolong samples I have recently ordered, so I'll post its review first.

Dry Leaf:

The dry leaf of this tea is very dark, as you can clearly see from the photo. Wuyi oolongs are known for their dark leaves, due to the relatively heavy oxidation and roasting they undergo during processing. The leaves are long and windy, and quite firm feeling. Though the leaves look pretty, it's their smell that is most noteworthy—this aroma is unbelievable. Rich, bold chocolate notes fill the nose, and a touch of cinnamon/cassia gives it a little character. Wuyi Bai Nian Lao Cong Shui Xian Dry LeavesSubtle hints of plum (or perhaps dark berries, it's hard to say) round it out, and give a nice body. There is no charcoal to be found in the dry leaf, though it does later present itself in leaves after infusing. Though the aroma of this tea is powerful, it remains well-balanced and mellow. This is easily the best "heavy" tea aroma I have yet come across.


Brewing vessel: Prewarmed glazed zisha gaiwan
Leaf amount: 1/2 of the gaiwan
Water temperature: 175°F
Steep times: 5s wash, 20s, 25s, 20s, ?, 30s, 40s, 60s


1st infusion: 20s, 175F
Wet Leaves: Slight charcoal aroma, outstanding chocolate note. Some fruit, but I can't tell what.
Liquor: Dark copper color. Full-bodied, fruity taste. Feels like chocolate is coating my tongue. Slight astringency.

2nd infusion: 25s, 175F
Wet Leaves: Slightly intensified charcoal, some chocolate and coffee.
Liquor: Still dark copper, maybe even red color. There is a less pronounced chocolate flavor, and less body. Slight coffee flavor. Little fruit, which is surprising. Stronger astringency.

3rd infusion: 20s, 175F
Wet Leaves: Less charcoal, more fruit and chocolate again.
Liquor: Less astringent than last time, but a bit drying. Chocolate has come back, as well as a bit of fruit.

4th infusion: ?s, 175F
Wet Leaves: Coffee predominates. Chocolate aroma is still present, though.
Liquor: Nice astringency. Chocolate and fruit flavors are definitely back again, but there is still not as much of a coating feeling as there was in earlier infusions. Too bad I forgot to time this one!

5th infusion: 30s, 175F
Wet Leaves: More charcoal again. This is proving to be a very finicky tea to brew just right, at least for me. There is some coffee and chocolate in the background.
Liquor: Fruit is coming through, as is chocolate. I let it cool by accident (I got distracted), but there was little astringency, surprisingly.

6th infusion: 40s, 175F
Wet Leaves: Chocolate and coffee dominate the nose now. Some charcoal is present, too.
Liquor: Lighter in color than previous infusions. Light-bodied, probably needs more steep time. Chocolate and fruit still present, but nothing is very strong in this brew. Virtually no astringency.

7th infusion: 60s, 175F
Wet leaves: Strong fruit aroma, some chocolate and charcoal. It's interesting that the fruit aroma should come out now, of all times.
Liquor: A bit weak—I think this tea is just about done. Some nice chocolate and fruit flavors are here though, despite the weakness.

Wuyi Bai Nian Lao Cong Shui Xian Wet LeavesWet Leaf:
Nice, big leaves. Note that most of the tears on these leaves resulted from my ham-fisted handling of them, but some of them were there beforehand as a result of processing. Still, this tea went through a fair amount of oxidation and roasting, so I'm not expecting perfect leaves. I'm also not an expert at analyzing wet leaves (or anything, for that matter), but those of you who do know what you're doing can see for yourself.


I think I may have found another favorite tea. Incredibly rich for the first few infusions, this tea was almost devoid of bitterness. The heavy mouth-feel and rich chocolate and fruity flavors make this a truly indulgent brew. This would make an excellent dessert tea. Due to its complexity, rich flavor, and most importantly the enjoyment I get from drinking it, Jing Tea Shop's 2005 Wuyi Bai Nian Lao Cong Shui Xian gets a 9/10.

Wednesday, April 18, 2007

Double Feature: Organic Tenbu and Tenbu Fuka Shaded Senchas

Class: Green
Origin: Kagoshima, Japan
Year: 2006 (?)
Vendor: Received courtesy of T Ching
Price: [Edit: Tenbu- $35.00 (50g); Tenbu Fuka- $39.00 (50g) WOW! I'm glad I got the free samples!]
Verdict: Tenbu- 9.5/10; Tenbu Fuka- 8.5/10

First, some background. T Ching has started to hold online tea tastings, where they send samples of select teas to a number of registered tasters who agree to taste the teas and post their notes online. This time, the category is shaded sencha. T Ching Samples 6 gram samples of two shaded senchas (Tenbu and Tenbu Fuka) were sent out, and tasting notes are beginning to accumulate here.

I have already posted my notes over at T Ching, but I figured that I'd post them here too. (Why not?) The only differences are that I've added links and images, I've bumped up the grade for the Tenbu Fuka, and I've changed some of the formatting to make it more like the rest of my reviews. The brewing parameters were identical for both teas: Unglazed Kyûsu (roughly 8oz volume); Brita-filtered tap water; 3 grams tea / 7oz water; 145°F for all infusions; 60s, 15s, 15s, 15s, 30s, 40s, 50s.

Tenbu:Tenbu Dry Leaves

Let's start with the dry leaves. They had a nice dark green color, with a fair amount of fannings (though this is not necessarily a bad thing in sencha). Also of note was the deep, grassy aroma. There were some marine notes too, but not much compared to some other senchas (like the fukamushi sencha I reviewed a long time ago). There is no hay smell at all, which is a good indicator of freshness.

The liquor was consistently a gorgeous, vibrant green. The first infusion was more peridot, followed by emerald, then lime in subsequent infusions. I tried to take a picture of the various infusions, but the color was not represented well at all. See Steven Dodd's review for a photo of the liquor color-- he was more successful than I was.

Tenbu PacketNow, on to the most important part: the taste. I thought this was an absolutely stunning tea. The liquor was wonderfully sweet, even candy-like. The first two infusions also had surprisingly thick mouth-feel, which I liked very much. There is little astringency, and I detected just a hint of grassiness in the first few infusions.

I thought it was truly spectacular that this sencha made it through 7 infusions. To be fair, the 7th infusion was weak and a bit insipid, but it was still tea (and good tea, I might add). When I first read that we would be preparing 5 infusions of a sencha, I thought someone was marginally insane, but needless to say I was proven quite wrong. Overall, I think this is a wonderful tea, and I would certainly purchase more if the option were available. For its excellent taste and utter lack of flaws according to my palate, the Organic Tenbu Shaded Sencha gets a 9.5/10.

Tenbu Fuka:Tenbu Fuka Dry Leaves

The dry leaf here is slightly more robust looking than the Tenbu, with fewer fannings. The leaf has a dark green color, similar to the Tenbu. Also, there are a few very long, wiry leaves. The aroma is more grassy and vegetal than the Tenbu, but overall I thought they smelled relatively similar.

The color of the Tenbu Fuka was almost as excellent as the Tenbu, but it wasn't quite as vibrant in every infusion. The third infusion was a beautiful lime color that surpassed the Tenbu at a similar stage, but I found the other infusions to be duller looking than the Tenbu. Still, compared to most other senchas, I thought the Tenbu Fuka displayed excellent color.

I think the Tenbu Fuka has the potential to be much more complex than the Tenbu, but unfortunately I do not think 3g is enough leaf. I found the same candy-like sweetness (perhaps the slightest touch of green apple candy), but I noticed a stronger grassy note and slightly more astringency as well. Tenbu Fuka PacketI also experienced a tingly, almost-perspiring body sensation (I know there is a word for this, but it is eluding me at the moment) at times, which I did not get from the Tenbu. Unfortunately, the way I brewed it, all of the infusions were slightly weak.

I was not quite as impressed with the Tenbu Fuka as I was with the Tenbu, though this may simply be due to not using enough leaf, as I was limited to the steeping conditions given by T Ching. I think that because there are fewer particles in the Tenbu Fuka, it may require slightly more leaf than the Tenbu to provide the same amount of surface area. Though the Tenbu Fuka seems to have a lot of potential, I still walked away feeling a bit underwhelmed. So, the Organic Tenbu Fuka gets an 8.5/10.


Overall, I liked the Tenbu more than the Tenbu Fuka. This surprised me because I figured, "Tenbu Fuka has a longer name, so it must be better." It is worth noting that others have liked the Tenbu Fuka slightly more, but I think it is safe to say that both of these teas were spectacular specimens, and depending on how they are brewed, the title of victor could go either way. Also, one point I have not yet touched on is the fact that these are both organic teas. Japanese organic teas do not have a great reputation at the moment in terms of flavor, so it was quite nice to find something organic and high quality. Now I just need to find a way to get a hold of more...

Monday, April 16, 2007

Anxi Gan De Hong Xin Tie Guan Yin from Jing Tea Shop

Class: Oolong
Origin: Gan De area of Anxi County, Fujian Province, China
Year: 2006
Vendor: Jing Tea Shop
Price: $23.80 (100g packet) / $6.20 (25g sample)
Verdict: 8/10

Jing Tea Shop LabelI frequently hear praise of a particular tea's "strong fruity flavor" or "amazing cinnamon smell," but rarely do I experience the same level of intensity when I try it for myself. This tea, Jing Tea Shop's Anxi Gan De Hong Xin Tie Guan Yin, is a remarkable exception. For once, I have found the description on a product page to be an understatement.

The dry leaves shocked me a bit when I first smelled them. I thought I would open up the bag to find a nice, delicate floral aroma, but what I found could be better described as an intense buttered broccoli/cauliflower smell. Don't get me wrong, it's a nice smell, but I wasn't expecting what I found. It's definitely a vegetal aroma that I hadn't come across until now.

Anxi Gan De Hong Xin Tie Guan Yin Dry LeafAs for looks, the dry leaf appears quite nice. There is a lovely mixture of bright green and dark blue-green colors in the leaves, and a bit of tan in the stems. Purty!

These leaves squeezed (not literally-- don't squeeze your tea) out more infusions than I could have possibly imagined. I got through 8 infusions without any significant loss of flavor, and I may have gotten 1 or 2 more in that session, but I was just too tired to keep going. Though I don't know much about how wet tea leaves should look, I do remember seeing something over at Hou De that said 3 leaves on a stem is a sign of hand-picked tea and of good quality. Anxi Gan De Hong Xin Tie Guan Yin Wet LeavesAs you can see, there are some of these in this tea. I wouldn't say that most of the leaves were this way-- actually, this is the best example I could find. Still, it's not as though the rest of the leaves are all fannings, they're just not clustered the same way. Anyway, on to the tasting:


Brewing vessel: Prewarmed glazed zisha gaiwan (I probably should have used the white porcelain one, but this seemed to work well enough)
Leaf amount: 1/5 of the gaiwan (I need a good scale, I know)
Water temperature: 165°F
Steep times: 5s wash, 10s, 10s, 15s, 20s, 25s, 25s, 30s, 30s


I'm just beginning to take these kinds of notes, so go easy on me. I just typed up my observations of the wet leaves and the liquor itself, though I tried to be attentive to other things as well. If you have any recommendations for me so that I can take better notes, I would be happy to hear them.

1st infusion: 10s, 165F
Wet Leaves: Smells like buttered broccoli, in a good way.
Liquor: Faint green-yellow color. Sweet, floral taste, lingers on the tip of the tongue. Light broccoli flavor, which becomes stronger as the infusion cools. Slightly buttery. Fuller body than I would have expected for such a light-colored tea. Very light astringency-- does not mask anything, but keeps the brew from feeling flat in the mouth.

2nd infusion: 10s, 165F
Wet Leaves: Starting to expand quite a bit. Stronger savory butter aroma... mmm!
Liquor: Slightly more intense color. Also a stronger buttery aroma. Behind the vegetal taste, there is a nice floral sweetness.

3rd infusion: 15s, 165F
Wet Leaves: More savory, even salty, buttery nose. There is still a noticable floral note (perhaps orange blossoms?), but it is overwhelmed by the intense buttery aroma.
Liquor: Similar color, a bit more yellow. Savory character is excellently displayed in this infusion, and the orange blossom just teases, like it is waiting to come out. Slightly stronger astringency, but very pleasant. It is drying and mouth-watering at the same time. [Note: this is the stimulating astringency that I described earlier.]

4th infusion: 20s, 165F
Wet Leaves: Similar to last time. Perhaps a bit more sweetness now.
Liquor: Sweeter taste coming through, definitely floral. Still buttery, but not quite as savory as before.

5th infusion: 25s, 165F
Wet leaves: More savory again. The leaves have expanded so much, they are overflowing out of the gaiwan. Still some floral aroma.
Liquor: A bit of a sharp bitter taste is present now. Slightly odd combination of sweetness and butteryness, as the sweetness is beginning to take over.

6th infusion: 25s, 165F
Wet leaves: The orange blossom note is now dominant, but only by a hair-- the butter is still well-established. There are several other minute aromas, but they elude characterization. Still, they make the aroma nicely complex.
Liquor: Still slightly awkward flavor. The floral sweetness is definitely kicking in, and I'm interested in seeing whether the buttery flavor will eventually give way.

7th infusion: 30s, 165F
Wet leaves: Fairly similar to last infusion. Perhaps a bit more butter again.
Liquor: Yes, orange blossom is now quite dominant. Butter is still lingering in the background, but orange blossom is the heart now.

8th infusion: 30s, 165F
Wet leaves: More butter, also starting to smell a little off, like bad butter.
Liquor: A little bitter, perhaps overbrewed, or maybe just running out of steam.


This was certainly an interesting tea, and I appreciate its complexity and its unique character. Still, it is tiresome to get through the middle infusions (4th-6th), which have an awkward combination of savory and sweet flavors. I also have a hard time preparing myself for such a savory tea as I tend to favor sweeter ones, but that is my fault and not that of the tea itself.

My favorite infusion was the 3rd, followed closely by the 7th. These were my favorites because they were the brews when the butter and floral notes best complemented each other. In the 3rd infusion, there was a subtle hint of orange blossom that I found intriguing, and in the 7th infusion, I found myself with more of a floral-tasting tea, but without any real loss of character.

Anxi Gan De Hong Xin Tie Guan Yin Dry LeafConclusion:

I didn't think that I would ever find a tea with such a strong pair of independent flavors, and I am quite impressed with how it completely transformed in flavor from the first infusion to the last. On technical details alone, I would give this tea a 9.5, but unfortunately I just didn't find it extremely enjoyable. The salty, savory flavor is nice, but not usually what I want in my tea; and the middle infusions are, unfortunately, not very pleasant. Even though Jing Tea Shop's Anxi Gan De Hong Xin Tie Guan Yin isn't as enjoyable as some other teas I have had, it was extremely interesting. Overall, it gets an 8/10.

Thursday, April 12, 2007

Biochemistry of Darjeelings and Oolongs

Thanks to Phyll Sheng, I came across this great article over at CHA DAO on some of the biochemistry behind Darjeeling and oolongs. If you're interested in this sort of stuff, definitely check it out-- there's a lot more info there than in my previous post about astringency and polyphenols.

Notes on the Biochemistry of Tea

Monday, April 09, 2007

Astringency: The Red-Headed Stepchild of Tea's Flavors


Astringency is quite possibly the least understood of tea's veritable cornucopia of flavors. Many people know it only as an unpleasant bitterness, but I would argue that this is NOT necessarily the case. While too much astringency can taste awful and bitter indeed, a total lack of astringency can leave your tea tasting flat and boring. The right amount, though, can add complexity and intrigue to your standard cuppa.

From my experience, I have noted four (4) kinds of astringency that can be found in tea-- some good, some bad. I must confess that I was only able to name / classify them after reading Kam Leung's page on what makes a good cup of Chinese tea, though I have slightly modified his list to better reflect my observations. So, without further ado...

The Four Types of Astringency
1. Rough Astringency

This is the kind of astringency that we have all likely noticed at one point or another. This is the unpleasant, extremely drying form of astringency that is not usually sought-after. This taste will leave your tongue uncomfortably dry for a prolonged period of time. Kam calls this type "Se."

2. Neutral Astringency

This type of astringency isn't really anything to write home about. This type will still leave your tongue feeling dry, but not nearly as uncomfortably as rough astringency will. Though I don't particularly like this type of astringency, I don't hate it either, and some people actually enjoy it. Often this is a natural property of the tea, and will come out no matter what, but sometimes it is a result of over-steeping or using too many leaves. Kam calls this type "Ku."

3. Stimulating Astringency

This is the kind of astringency that I love and crave. It is unique in that it seems to stimulate your tongue to produce excess moisture, and leaves your tongue feeling oddly dry and wet at the same time. It can also produce a kind of cooling effect when you breathe. Kam notes that this is also a minty feeling, and calls it "Gan."

Kan also describes "Hui Gan," which is a prolonged stimulating astringency (minutes to hours). This is very rare, and very very nice. I have only experienced this once or twice, as you need a very high quality tea and the brewing has to be right on the spot. I've only experienced this with the Makaibari Vintage Muscatel Second Flush Darjeeling that I reviewed earlier, but I'm sure there are others out there that can produce this wonderful effect.

4. Metallic/Organic Astringency

This type of astringency is absolutely awful. It may simply be an extreme form of rough astringency (Se), but it is so horrid that I think it deserves its own category. I have most often encountered this astringency when brewing gyokuro (shaded Japanese green tea) with water that is far too hot, but it can manifest itself in other non-/lightly-oxidized teas as well when brewed with too much leaf or too much heat. As you could likely surmise from the name, this type of astringency is marked by a metallic, yet also strangely organic taste. If I ever get this in my tea, I just throw out the entire infusion. Note that if you get this flavor, it is almost definitely a result of human error-- I don't think any producer makes tea that intentionally tastes like this.

The Science behind Astringency

Though I have absolutely no idea what causes one type of astringency to present itself versus the others, but I can share a bit about the basics behind the chemistry of astringency. Despite what you may have heard, tannins are not responsible for astringency or bitterness in tea. There are essentially zero tannins in tea. As far as I can tell, the word "tannins" only became part of the tea lexicon because tannins cause astringency in wine, and someone just ported it over to describe tea. The correct term for the compounds that cause astringency in tea is polyphenols. Though tannins are also polyphenols, not all polyphenols are tannins.

EGCG Chemical StructureThe simplest polyphenol is just an aromatic ring with two or more hydroxyl (-OH) groups attached to it (as opposed to an aromatic ring with only one hydroxyl, which is simply called phenol), but biological polyphenols are often much more complicated than this. The majority of polyphenols found in tea are catechins, which make up about 25% of the leaf's dry weight, such as EGCG (epigallocatechin gallate), shown here.

Polyphenols cause the astringent sensation by binding with salivary proline-rich proteins (proline is one of the 20 main amino acids, and is quite unique in its structure) to form insoluble chemical complexes, thus reducing salivary lubrication, causing a drying sensation in the mouth. An abstract discussing this mechanism can be found here).

***Somewhat related notes: During processing, some of these polyphenols are oxidized to theaflavins and thearubigins, which give black tea some of its flavors and colors. Also, polyphenols such as EGCG have been shown to have potent antioxidant properties, which has attracted quite a bit of attention (thanks Snapple) as of late.***

The Bitter End

Though it is often looked down upon and considered as nothing more than bitterness, I think the right kind of astringency can be one of tea's most interesting characteristics. Hopefully, this information will allow many of you tea drinkers to more fully appreciate the astringent qualities of tea, or at least think twice about using the word "tannins" ever again (please, I'm begging you).

Thursday, April 05, 2007

Behind the scenes at Tea Nerd

Hey all, just wanted to keep you up-to-date. I haven't done any reviews lately, because I've just received a whole bunch of oolongs and I've been teaching myself how to properly taste them. I've improved my gaiwan-brewing skills a great deal, and I think I've found another favorite tea. Anyway, in a week or two I'll start putting up a series of wuyi oolong notes and reviews, so stay tuned.

Also, during my absence, I encourage you all to visit the other tea blogs I have listed on the left-hand side of this page-- there are some real gems in there, and some that put this little project to shame.

As always, brew, drink, and be nerdy.