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Tea (rec.drink.tea) Discussion relating to tea, the world's second most consumed beverage (after water), made by infusing or boiling the leaves of the tea plant (C. sinensis or close relatives) in water. |
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Questions concerning Tea and its benefits
Does anyone know a good source for green tea containing high amounts
of EGCG? |
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Questions concerning Tea and its benefits
On Jun 3, 1:21 am, wrote:
> Does anyone know a good source for green tea containing high amounts > of EGCG? I thought all green teas had the same level of EGCG. |
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Questions concerning Tea and its benefits
On Jun 4, 8:08 am, Desirea > wrote:
> On Jun 3, 1:21 am, wrote: > > > Does anyone know a good source for green tea containing high amounts > > of EGCG? > > I thought all green teas had the same level of EGCG. Indeed they do not! The five types of catechins in tea (gallated flavonols and non gallated flavanols collectively) occur at different levels and in different ratios depending on genetic background and growing environment. Levels of EGCG (epigallocatechin gallate) can be higher or lower than some of the other catechins. Typical levels in African teas (assamica) are much higher than in China type teas (sinensis) when the Africans are manufactured the green tea way. For example (see "Diversification of the Tea Product through Value Adding and Business Viability - H.E Nyirenda et al, TRFCA News 2006 p20) cultivar PC190 had EGCG of 329.3 mmol/g while cultivar PC160 had only 165.9 - 24 other cultivars fell between these limits. You can perhaps have too much of a good thing though and PC190 while having the highest level of flavonols was rejected for release to growers as it produced poor quality tea. Nevertheless several of my clients are pursuing intrinsically high EGCG as a marketing USP, along with naturally high L-theanine levels - these are staggeringly high in Malawi clones - PC108 has 3.1 % theanine compared with Japanese culivars at 1.5% under sun - and the Japanese teas are recognised for their theanine content which by shading can still only reach two thirds of the Malawi level! Nigel at Teacraft |
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Questions concerning Tea and its benefits
Usually these numbers are gathered from the analysis of fresh green
leaves. However, if you´re planning to sell and ship those leaves you´re at least supposed to kill the enzymes, in order to block any kind of reaction with the polyphenols. That means you have to give them some heat treatment, steaming, hot air, panning or whatever, which might result in a slightly different picture, but a high content of EGCG in fresh leaves would be a good point to start. PS: I really enjoy this kind of tea-tech-talk Karsten [still dreaming of a pocket-chromatograph] On Jun 4, 11:07 am, Nigel > wrote: > On Jun 4, 8:08 am, Desirea > wrote: > > > On Jun 3, 1:21 am, wrote: > > > > Does anyone know a good source for green tea containing high amounts > > > of EGCG? > > > I thought all green teas had the same level of EGCG. > > Indeed they do not! > > The five types of catechins in tea (gallated flavonols and non > gallated flavanols collectively) occur at different levels and in > different ratios depending on genetic background and growing > environment. Levels of EGCG (epigallocatechin gallate) can be higher > or lower than some of the other catechins. Typical levels in African > teas (assamica) are much higher than in China type teas (sinensis) > when the Africans are manufactured the green tea way. For example > (see "Diversification of the Tea Product through Value Adding and > Business Viability - H.E Nyirenda et al, TRFCA News 2006 p20) cultivar > PC190 had EGCG of 329.3 mmol/g while cultivar PC160 had only 165.9 - > 24 other cultivars fell between these limits. You can perhaps have too > much of a good thing though and PC190 while having the highest level > of flavonols was rejected for release to growers as it produced poor > quality tea. Nevertheless several of my clients are pursuing > intrinsically high EGCG as a marketing USP, along with naturally high > L-theanine levels - these are staggeringly high in Malawi clones - > PC108 has 3.1 % theanine compared with Japanese culivars at 1.5% under > sun - and the Japanese teas are recognised for their theanine content > which by shading can still only reach two thirds of the Malawi level! > > Nigel at Teacraft |
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Questions concerning Tea and its benefits
On Jun 4, 8:07 am, wrote:
> Usually these numbers are gathered from the analysis of fresh green > leaves. > However, if you´re planning to sell and ship those leaves you´re at > least supposed to kill the enzymes, in order to block any kind of > reaction with the polyphenols. That means you have to give them some > heat treatment, steaming, hot air, panning or whatever, which might > result in a slightly different picture, but a high content of EGCG in > fresh leaves would be a good point to start. > PS: I really enjoy this kind of tea-tech-talk > > Karsten [still dreaming of a pocket-chromatograph] > > On Jun 4, 11:07 am, Nigel > wrote: > > > On Jun 4, 8:08 am, Desirea > wrote: > > > > On Jun 3, 1:21 am, wrote: > > > > > Does anyone know a good source for green tea containing high amounts > > > > of EGCG? > > > > I thought all green teas had the same level of EGCG. > > > Indeed they do not! > > > The five types of catechins in tea (gallated flavonols and non > > gallated flavanols collectively) occur at different levels and in > > different ratios depending on genetic background and growing > > environment. Levels of EGCG (epigallocatechin gallate) can be higher > > or lower than some of the other catechins. Typical levels in African > > teas (assamica) are much higher than in China type teas (sinensis) > > when the Africans are manufactured the green tea way. For example > > (see "Diversification of the Tea Product through Value Adding and > > Business Viability - H.E Nyirenda et al, TRFCA News 2006 p20) cultivar > > PC190 had EGCG of 329.3 mmol/g while cultivar PC160 had only 165.9 - > > 24 other cultivars fell between these limits. You can perhaps have too > > much of a good thing though and PC190 while having the highest level > > of flavonols was rejected for release to growers as it produced poor > > quality tea. Nevertheless several of my clients are pursuing > > intrinsically high EGCG as a marketing USP, along with naturally high > > L-theanine levels - these are staggeringly high in Malawi clones - > > PC108 has 3.1 % theanine compared with Japanese culivars at 1.5% under > > sun - and the Japanese teas are recognised for their theanine content > > which by shading can still only reach two thirds of the Malawi level! > > > Nigel at Teacraft Thank you all for your tremendous input. I know that when processing tea's most of the times when they go through what is called a roto- machine it slices the leaves for further processong of tea bags. This actually damages the cell wall and allows for quicker oxidation. Traditionally steaming( more a japanese method) and pan frying ( more a chinese method) are safer in that they delicately roll the leaves so as to protect them from damage. I did not know however that the assamica plant contained more EGCG thats its cousin the sinensis plant. I was under the impression that the Assamica plant came after the Sinensis plant when the british invaded India as a result of china cutting off its trade market back in the 1700's. |
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Questions concerning Tea and its benefits
Nigel > wrote:
> >The five types of catechins in tea (gallated flavonols and non >gallated flavanols collectively) occur at different levels and in >different ratios depending on genetic background and growing >environment. Levels of EGCG (epigallocatechin gallate) can be higher >or lower than some of the other catechins. Is there an easy kitchen sink titration for catechins? I know there is a chromatographic analysis that is a pain in the neck to do, for folks without HPLC hardware. Typical levels in African >teas (assamica) are much higher than in China type teas (sinensis) >when the Africans are manufactured the green tea way. For example >(see "Diversification of the Tea Product through Value Adding and >Business Viability - H.E Nyirenda et al, TRFCA News 2006 p20) cultivar >PC190 had EGCG of 329.3 mmol/g while cultivar PC160 had only 165.9 - >24 other cultivars fell between these limits. You can perhaps have too >much of a good thing though and PC190 while having the highest level >of flavonols was rejected for release to growers as it produced poor >quality tea. What makes good tea is a balance between different flavours, and I can't help but think of catechins as important (and not subtle) tea flavours. Nevertheless several of my clients are pursuing >intrinsically high EGCG as a marketing USP, along with naturally high >L-theanine levels - these are staggeringly high in Malawi clones - >PC108 has 3.1 % theanine compared with Japanese culivars at 1.5% under >sun - and the Japanese teas are recognised for their theanine content >which by shading can still only reach two thirds of the Malawi level! And this, in short, is what makes tea interesting. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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Questions concerning Tea and its benefits
> wrote:
> I did not know however that the >assamica plant contained more EGCG thats its cousin the sinensis >plant. I was under the impression that the Assamica plant came after >the Sinensis plant when the british invaded India as a result of >china cutting off its trade market back in the 1700's. It may not be the plant species at all; it may be weather or soil conditions. This is where things get interesting; if you take a plant from one place and put it in another place, the tea tastes different and correspondingly a chemical analysis will be quite different as well. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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Questions concerning Tea and its benefits
Hey,just to add that tea age plays an important part.
To quote Bokuchava The first and second leaves of the shoot are richest in catechins. As the leaf ages, the content of total catechins decreases with the amount of EGCG and ECG falling sharply and the amount of EGC and EC rising. .... the site of catechin synthesis in the tea plant is in young leaves and shoots. It's interesting to know that EGCG and ECG tastes more astringent than the other catechins. That's the reason why more matured leaves (which has less of EGCG and ECG) are used to make oolong and black tea. For further information about the advantages of tender tea shoots when drinking green tea, read http://www.amazing-green-tea.com/tender-tea-shoots.html Julian http://www.amazing-green-tea.com |
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Questions concerning Tea and its benefits
juliantai > writes:
> [...] > > It's interesting to know that EGCG and ECG tastes more astringent > than the other catechins. That's the reason why more matured leaves > (which has less of EGCG and ECG) are used to make oolong and black > tea. I'm not so sure about this argument. It's hardly unusual for black/red tea to be made from young shoots. And the main reason oolong is made from mature leaves, I think, is that they hold up better under the kneading and rolling during manufacture. /Lew --- Lew Perin / http://www.panix.com/~perin/babelcarp.html |
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Questions concerning Tea and its benefits
On Jun 5, 9:01 am, juliantai > wrote:
> Hey,just to add that tea age plays an important part. > > To quote Bokuchava > > The first and second leaves of the shoot are richest in catechins. > > As the leaf ages, the content of total catechins decreases with the > amount of EGCG and ECG falling sharply and the amount of EGC and EC > rising. > > ... the site of catechin synthesis in the tea plant is in young leaves > and shoots. > > It's interesting to know that EGCG and ECG tastes more astringent > than the other catechins. That's the reason why more matured leaves > (which has less of EGCG and ECG) are used to make oolong and black > tea. > > For further information about the advantages of tender tea shoots when > drinking green tea, read > > http://www.amazing-green-tea.com/tender-tea-shoots.html > > > > Julianhttp://www.amazing-green-tea.com Nice to have someone quoting Bokuchava at last - the Soviet's Father of Tea and tireless and innovative researcher in tea processing and discoverer of Vitamin P in tea - though whether it is an actual vitamin is a trifle contentious. His daughter was still, in 2004, carrying the Bokuchva banner aloft at the Tea Reseach Instititute in Anaseuli (West Georgia), though the walls, made of inferior Soviet concrete, were parting company with the floors. Its good to see data quoted but it's a pity about the Tables in www.amazing-green-tea not having more accuracy in their units. In Table 1 for example 150.32 milligrams per gram is shown for catechins in the Bud & 1 Leaf in percentage terms this is only 15% catechin - low even for a Japanese clone (Yabukita 19.8% and Benihomare 25.6% - according to Nakagawa, and for a black tea clone's Bud & 1 Leaf shoot try 35% catechins - Nant). In Table 2 Column 2 should be headed Soluble Solids not Solubility, though these figures are suspiciously high showing 37.91% for 6th leaf even if it were a 6 leaf and bud shoot rather than just the 6th leaf as indicated. In Turkey the soluble solids for a 6 leaf shoot would struggle to get above 29%. Polyphenols are OK as shown but the Catechins cannot be higher than the total Polyphenols. And 76.3% catechins in the 3rd leaf would be a biochemical anomoly and a bitter cup indeed!! Nigel at Teacraft |
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Questions concerning Tea and its benefits
> Table 1 for example 150.32 milligrams per gram is shown for catechins > in the Bud & 1 Leaf in percentage terms this is only 15% catechin - > low even for a Japanese clone (Yabukita 19.8% and Benihomare 25.6% - > according to Nakagawa, and for a black tea clone's Bud & 1 Leaf shoot > try 35% catechins - Nant). In Table 2 Column 2 should be headed > Soluble Solids not Solubility, though these figures are suspiciously > high showing 37.91% for 6th leaf even if it were a 6 leaf and bud > shoot rather than just the 6th leaf as indicated. In Turkey the > soluble solids for a 6 leaf shoot would struggle to get above 29%. > Polyphenols are OK as shown but the Catechins cannot be higher than > the total Polyphenols. And 76.3% catechins in the 3rd leaf would be a > biochemical anomoly and a bitter cup indeed!! > > Nigel at Teacraft I know I have to do extra work when Nigel (or Dogma) is involved First, just to mention that the article is designed for an average tea drinkers with zero knowledge of green tea, and the point to illustrate is that younger tea shoots contain more catechins and theanine. Anything more I add to the article would simply confuse my audience. Now back to Nigel ... The figures I quoted are typical of Chinese literature, where polyphenol is around 30% and catechins below 20%. I don't think they look unreasonable. The 15% catechins content is for fresh leaf, which in percentage term will be lower compared to dried tea extract. Harold Graham in his paper Green Tea composition (1992) quoted a range of 16% to 30% for fresh tea leaves, and 30% tp 40% for extract solids. So yes, the catechins look low, but is still within a reasonable range. Are your figures for fresh leaves or dried tea extract? The second table is open for interpretation. I've left it as it's because it illustrates the point that younger tea shoots contain more catechins than the older ones. It appears to me that the 76.3% is as a percentage of something, maybe the polyphenol, but I am not sure. It'll tie in as catechins consist about 70% of polyphenol, although the reduction seems quite rapid with age. Now to Lewis... <I'm not so sure about this argument. It's hardly unusual for <black/red tea to be made from young shoots. And the main reason <oolong is made from mature leaves, I think, is that they hold up <better under the kneading and rolling during manufacture. Generally speaking, high grade green tea is made from a single bud up to two adjacent leaves. Whereas oolong tea or red tea is made from the 2 to 4 leaves. There are exceptions, like the famous green tea Liu an Gua Pian. Processing is important. But the chemical difference between the two is important too. Julian http://www.amazing-green-tea.com |
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On Jun 5, 7:11 pm, juliantai > wrote:
> The 15% catechins content is for fresh leaf, which in percentage term > will be lower compared to dried tea extract. Harold Graham in his > paper Green Tea composition (1992) quoted a range of 16% to 30% for > fresh tea leaves, and 30% tp 40% for extract solids. So yes, the > catechins look low, but is still within a reasonable range. > > Are your figures for fresh leaves or dried tea extract? > Julian, my figures are in % dry weight of oven dried fresh leaf - standard science methodology. Hal Graham, as a scientist, quotes in % dw of fresh leaf (this data came from the bushes at the TJ Lipton Tea Farm in Charleston, SC) and, as former President of TJ Lipton, quotes for steeped tea beverage in the cup (in wt % of extract solids). Differential solubility in hot water leads to all sorts of problems in correlation between the two systems - for example he gives 3.5% methylxanthines (caffeine) on whole leaf basis but 7-9% methylxanthines on an extracted green tea beverage basis - and even higher at 8-11% for an extracted black tea beverage - that's up to 11% of the solids in your Yellow Label tea is caffeine; fortunately its 11% of just 0.3 to 0.35% extract concentration in the cup (from Hal's data) - a more reasonable 100 mg caffeine in a large mug (my calculation). Similarly with catechins at 16-30% by dw in the field but reaching 30-42% by dw in the cup. Beverage preparation method has an over riding effect on what can be extracted and how much (tell me what figure you want and I will devise a method to provide it) - so science uses the absolute % dw of fresh leaf method. Hal himself admits of the beverage preparation method "little is known about the ability of a normal hot aqueous infusion to extract some of the compounds recently reported in dried green tea leaf" Nigel at Teacraft |
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Questions concerning Tea and its benefits
juliantai > writes:
> [...] > > <I'm not so sure about this argument. It's hardly unusual for > <black/red tea to be made from young shoots. And the main reason > <oolong is made from mature leaves, I think, is that they hold up > <better under the kneading and rolling during manufacture. > > Generally speaking, high grade green tea is made from a single bud up > to two adjacent leaves. Yes, *high grade* green tea. I think high grade red tea tends to be plucked similarly. > Whereas oolong tea or red tea is made from the 2 to 4 leaves. There > are exceptions, like the famous green tea Liu an Gua Pian. > > Processing is important. But the chemical difference between the two > is important too. Of course chemical differences are important. My point was that they aren't the whole explanation for which stages of the tea plant's growth are used in various types of made tea (green, oolong, red, etc.) Think of it another way. These practices go back centuries to a great extent. Were the Fujianese farmers who developed oolong technology in the Ming dynasty thinking about catechins? /Lew --- Lew Perin / http://www.panix.com/~perin/babelcarp.html |
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Questions concerning Tea and its benefits
Lewis
> Yes, *high grade* green tea. I think high grade red tea tends to be > plucked similarly. That's very interesting. A high grade green tea can be made from a single bud (que shi, anji bai cha), one bud one leaf (bi luo chun) or one bud two leaves (tai ping hou kui). I am not aware of any oolong or red tea that is made from single buds or one bud and one leaf, but I'm sure that are some, as you implied. > Of course chemical differences are important. My point was that they > aren't the whole explanation for which stages of the tea plant's > growth are used in various types of made tea (green, oolong, red, Thanks, I get it now. > etc.) Think of it another way. These practices go back centuries to > a great extent. Were the Fujianese farmers who developed oolong > technology in the Ming dynasty thinking about catechins? They allow for it in the tea selection process. Younger leaves for green tea and more matured leaves for oolong and red tea. Green tea in Spring and oolong tea for autumn, each with their own chemical profile. All factored in Lewis, just want to say thank for your babelcarp tool, it's excellent. Julian http://www.amazing-green-tea.com |
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Questions concerning Tea and its benefits
Nigel, I did notice the 11% caffeine figure he quoted, thank you for
shining the light on this one. > correlation between the two systems - for example he gives 3.5% > methylxanthines (caffeine) on whole leaf basis but 7-9% > methylxanthines on an extracted green tea beverage basis - and even > higher at 8-11% for an extracted black tea beverage - that's up to 11% > of the solids in your Yellow Label tea is caffeine; fortunately its > 11% of just 0.3 to 0.35% extract concentration in the cup (from Hal's Did you mean "11% of just 30% to 35%" i.e. the soluble solids? I'm happy with your answer. And thanks for pointing out the apparent anomaly Julian http://www.amazing-green-tea.com |
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Questions concerning Tea and its benefits
juliantai > writes:
> Lewis > > > Yes, *high grade* green tea. I think high grade red tea tends to be > > plucked similarly. > > That's very interesting. A high grade green tea can be made from a > single bud (que shi, anji bai cha), one bud one leaf (bi luo chun) or > one bud two leaves (tai ping hou kui). I am not aware of any oolong or > red tea that is made from single buds or one bud and one leaf, but I'm > sure that are some, as you implied. I certainly didn't imply that for oolong: quite the reverse. Oolong is usually made from big, mature leaves. As for reds, bud-only Dian Hong is a treat, though it's expensive. TeaSpring currently advertises a bud-only Sichuan red: http://www.teaspring.com/Sichuan-Gongfu.asp Bud-and-one-leaf, let alone, two, is correspondingly more common. > > Of course chemical differences are important. My point was that they > > aren't the whole explanation for which stages of the tea plant's > > growth are used in various types of made tea (green, oolong, red, > > Thanks, I get it now. > > > etc.) Think of it another way. These practices go back centuries to > > a great extent. Were the Fujianese farmers who developed oolong > > technology in the Ming dynasty thinking about catechins? > > They allow for it in the tea selection process. Younger leaves for > green tea and more matured leaves for oolong and red tea. Green tea in > Spring and oolong tea for autumn, each with their own chemical > profile. All factored in > > Lewis, just want to say thank for your babelcarp tool, it's excellent. Thanks! /Lew --- Lew Perin / http://www.panix.com/~perin/babelcarp.html |
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Questions concerning Tea and its benefits
On Jun 3, 7:21 am, wrote:
> Does anyone know a good source for green tea containing high amounts > of EGCG? Not exactly EGCG but I just ran into this website on GABA [Gamma- aminobutyric acid]. Just in case somebody is interested in some additional health related tea tech. Karsten |
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