Japan Tannin is the general term for the aromatic compounds which have hydroxyphenole-group found in many plant species.
Catechins are major forms of tannin in tea leaves.
In recent years catechins have attracted a lot of attention due to its potential for promoting good health in the human body. PAL has been considered the key enzyme for tannin biosynthesis. QTL of tannin ingredient was detected, but QTL of PAL activity was not observed. PAL activity was not related to tannin ingredient. CHS has also been considered to play a great role on tannin biosynthesis.