The chemical basis of quality in tea. II.-analyses of withered leaf and of manufactured tea

Respiratory losses caused losses of total solids during the withering process in tea manufacture, and there were further slight losses during the later stages of manufacture. Protein breakdown occurring during withering was accompanied by increases in amino‐acids and in the amounts of caffeine extracted. Decreases in water‐soluble solids as a result of manufacture were attributed partly to respiratory losses and partly to a combination of polyphenolic oxidation products with protein. The decrease in the Löwenthal permanganate titre, which takes place as a result of manufacture, was considered to be due partly to the insolubilisation of polyphenolic oxidation products by combination with protein, and partly to oxidation to substances (theaflavins, thearubigins, etc.) which had lower permanganate titres than the parent flavanols.