Biological and chemical factors affecting the valuation of North East Indian plains teas. III. Statistical Evaluation of the Biochemical Constituents and their Effects on Colour, Brightness and Strength of Black Teas

Regardless of tasters and methods of manufacture five biochemical factors, total oxygen uptake of unprocessed tea shoots and theaflavins (TF), thearubigins (TR), (−)‐epigallocatechin gallate (EGCE) and theogallin (TG), of black tea are the main contributing factors of colour of North East India plains tea. Similarly, three constituents, TF, TR and (−)‐epicatechin gallate (ECG) of black tea, are main the factors for brightness. Four factors, total oxygen uptake and ECG of unprocessed tea shoots and TF and moisture of black tea are the main contributing factors of strength of North East Indian plains tea.