Questions concerning Tea and its benefits

Does anyone know a good source for green tea containing high amounts of EGCG?

Reply to
tea.expert
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I thought all green teas had the same level of EGCG.

Reply to
Desirea

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

Reply to
Nigel

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

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

And this, in short, is what makes tea interesting.

--scott

Reply to
Scott Dorsey

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

Reply to
Scott Dorsey

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

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:)

Julian

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Reply to
juliantai

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

Reply to
Lewis Perin

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

Reply to
Nigel

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...

Reply to
juliantai

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

Reply to
Nigel

Yes, *high grade* green tea. I think high grade red tea tends to be plucked similarly.

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

Reply to
Lewis Perin

Lewis

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.

Thanks, I get it now.

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

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Reply to
juliantai

Nigel, I did notice the 11% caffeine figure he quoted, thank you for shining the light on this one.

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

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Reply to
juliantai

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:

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Bud-and-one-leaf, let alone, two, is correspondingly more common.

Thanks!

/Lew

Reply to
Lewis Perin

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

Reply to
psyflake

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