Sunday, December 11, 2011

Tea - the Wonder Beverage Part 3: The Chemistry of Tea

This is Part 3 of my series on the Wonder Beverage. Part 1 can be found here. Part 2 can be found  here.
  
Tea chemistry is based on the reactions of its polyphenols. Therefore it is important to select the part of the tea plant which is most abundant with polyphenols, for further processing.

Tea plants are trees.  Left in their natural state they grow tall with woody trunks.

 

But in tea plantations they are assiduously pruned so that they grow low, branching and bushy.



Tea pluckers pluck the surface of the bush. They harvest the first two leaves and the bud of the sprigs.


These immature vegetative portions, the rapidly growing shoot tips, are collectively called the tea flush. When we compare the composition of the tea flush with that of other parts of the tea plant, tea flush has the highest amount of polyphenols.

Plucking the tea flush fixes the chemical potential of the tea leaf, which is the raw material which goes in to the manufacturing process, to make the tea product. The quality attributes of the final product depend largely on the chemical composition of the raw material, namely the fresh green tea leaf.