ISO/TS 5617:2025

Tea — Classification by chemical composition Published (Edition 1, 2025)

Abstract

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.