ISO/PWI TS 5617

Tea — Classification by chemical composition

Scope

This document specifies a method to classify six tea types (black tea, green tea, white tea, oolong (blue) tea, dark tea and yellow tea) based on statistical analysis of chemical compositions. The key X1 to X6 determinants (total catechins, caffeine, theanine, epigallocatechin gallate (EGCG)/total catechins, theanine × theanine, theanine × caffeine) for tea chemical classification were extracted from these critical compositions by statistical methods, from a large-scale chemical analysis of samples of six tea types, which can be used as principal components to classify the particular tea by Fisher’s step-by-step discrimination formulae.[6][7]
This document is applicable to the classification of both primary and refined teas, and is particularly suitable for teas produced in China. It does not apply to reprocessed teas.