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."