The chemistry of tea manufacture

Many of the substances occurring in freshly plucked tea shoots are listed and the chemical changes taking place during withering and fermentation are discussed. In fermentation (—)‐epigallocatechin and its gallate are the only polyphenols to undergo appreciable chemical change. A scheme for the oxidation of these substances is developed which suggests that substances A, B and C are bisflavanols, and that theaflavin and theaflavin gallate are derivatives of purpurogallin. Thearubigins are probably formed as a result of coupled oxidation of theaflavins. Structures are also suggested for the minor components P, Q, R and Z. It is probable that theaflavins and thearubigins account for the colour and strength of tea liquors, and that theaflavins also contribute towards quality and briskness.