Natural chemical compositions are different by tea types.  Gyokuro, Matcha, and Kabusecha contain more amino acids and caffeine.  While Sencha has more catechins.  The cultivation method makes the difference.  And here are some reasons behind the graph.

 

Tannin (Catechin)

Tea catechin increases as the leaves receive more sunshine.  Therefore, Sencha and Tamaryokucha have more catechins than Gyokuro and Matcha, which are cultivated in shade under sheets.  While young shoots contain more catechins than mature leaves.  This is why Bancha with mature leaves contain less catechins.

 

Caffeine

Shading cultivation delays the reduction of caffeine.  So Gyokuro and Matcha have more caffeine than Sencha and TamaryokuchaHoujicha has less caffeine than Sencha or Tamaryokucha, because of the roasting process.

 

Amino acids

Amino acids have similar characteristics as caffeine.  Teanine is the biggest chemical component in amino acids, quickly turning to catechins and other polyphenol in the leaves.  But shading cultivation suppresses such decomposition.  Therefore Gyokuro and Matcha keep more amino acids than Sencha and Tamaryokucha.

 

Natural chemical compositions are not only different by tea types, but also by the time of  harvest. An earlier harvest contains more amino acids, while a later harvest contains more Tannin (Catechin).  All three natural chemical components decrease as leaves mature.

(Chemical Composition of Japanese Green Teas on Market, 1994, P23-28, No.80, Tea Research Journal)

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