The chemistry of the tea leaf T he chemical composition of the tea leaf is of interest mainly because of the reactions that take place during its manufacture. The inorganic constituents are found mainly as salts in the cellsap. The Nitrogen Compounds Three-quarters of the nitrogen in the leaf consists of proteins and aminoacids that are basic constituents of the protoplasm. The remaining quarter is from the alkaloid caffeine.
Lipids occur in the general protoplasm and Pectins are present in quite large amounts in tea.
The most important and characteristic components of tea leaf are polyphenols. The polyphenols, like alcohols, are a very large class and properties and derivatives differ widely. Those occurring in tea are derivatives of gallic acid and catechin. There are four main compounds with chemical configurations based on catechin and gallic acid. The oxidation of tea polyphenols on exposure to air is exceedingly slow unless brought about by the activity of the appropriate enzyme.