What catechins means
Catechins are a family of flavan-3-ol polyphenols that make up a large share of the dry weight of green tea leaf. Epigallocatechin gallate, or EGCG, is the most abundant and the strongest contributor to astringency. Shading suppresses catechin formation in tencha, which is one reason high grade matcha tastes more umami and less bitter than sun-grown leaf. Published assays from Japanese tea research institutes consistently show lower catechin levels in shaded ichibancha than in later, unshaded harvests.
Also called
Catechins also appears as tea polyphenols, EGCG.