• CHEMISTRY OF TEA LEAF – II

  Filed under Teamoods
  Jan 19

  Continuation…. 

  TANNIN may be 22% in fresh leaf but it can drop to 10% when leaf has been manufactured. Tannin from tea develops pungency after contact with oxygen in air, and oxidation, which if uncontrolled, will soon render Tannin insoluble in water de to loss of tannic value.  Tannin content of leaf can drop by 4% or more in leaf growing on bushes under heavy shade. Tannin content of leaf can be lowered by heavy doses of Nitrogenous manures; 45 to 80 lbs. Nitrogen per acre produces leaf rich in Tannin. 

  TEA POLYPHENOL OXIDASE is the ENZYME in tea leaf tissue which, with sufficient aeration, can oxide all oxidizable matter which is rolled out of leaf, or is otherwise exposed. Enzymes & Polyphenols similar to those in Tea are present in some apples and potatoes, hence there is discoloration of the flesh directly it is exposed to air or oxygen.  Principal constituents of Tea leaf are a group of soluble substances or oxidizable matter together with Pectins, Caffeine and Aromatics. 

  PECTINS in Tea leaf are:
  Bud                  4.94% of weight
  1^st Leaf            6.09% of weight
  2^nd Leaf           4.68% of weight
  Stalk                7.59% of weight 

  Soluble Matter: Tea leaves contain the following soluble:
  Tannin              22%                
  Starch              1%
  Caffeine            4%                 
  Sugars              1%
  Protein etc.       16%                
  Pigments           2% 

  Insoluble Matter: Tea leaves contain the following insoluble:
  Crude Fibers    22%                
  Proteins           18%
  Cellulose          13%                
  Residues          1% 

  TANNIN CONTENT varies with age since pruning with average percentages:10 to 12% at 6 months from pruning12 to 16% at 12 months from pruning18 to 19% at 24 months from pruning15 to 20% at 36 months from pruning

  
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