Hierarchical
clustering analysis of the sixteen tested samples was also
performed based on the Trolox equivalent concentrations of the ten
bioactive components. The results presented in Fig. 5B showed clearly
that sixteen tested samples were appropriately divided into two main
clusters. The samples of oolong tea (S7–S12) were grouped as one
distinct cluster (Cluster I). The samples of green tea and white tea
(S1–S6 and S13–S16) shared a close similarity, and were grouped as
Cluster II; however, a detail analysis revealed that another two clusters
were developed. The samples of green tea from S1 to S6 could
be grouped as one cluster (Cluster II-1), and the samples of white
tea could be grouped as another cluster (Cluster II-2), i.e. S13 to
S16. This grouping was in agreement with the result of PCA.