Flavonol glycosides
Present in small amounts, detectable at very low ones, and a large contributor to the velvety, mouth-coating dryness catechins alone do not explain.
What a drinker notices
- Astringency — a tactile sensation
- Colour — appearance
A velvety, mouth-coating dryness rather than a sharp grip — the quality tasters call silky when it is in balance and dusty when it is not. It also supplies a good part of the yellow in a green liquor.
How much of it there is matters: Detectable far below the level at which catechins register at all, so a tea can be perceptibly drying while its measured polyphenol figure suggests it should be mild.
What this gets credited for, wrongly
Mouthfeel in green tea is attributed to catechins almost universally. Catechins supply the grip; a large part of the coating, velvety quality belongs to this group, and no catechin measurement will predict it.
What it is
Flavonol glycosides sit at a fraction of the catechin level and punch far above it, because the sensory threshold for this group is remarkably low. They contribute a soft, velvety, mouth-coating dryness — different in character from the sharper grip of the galloylated catechins — and they are a large part of why the total polyphenol figure of a tea predicts its texture so poorly. They also carry much of the yellow in a green tea liquor. Their presence is the standing argument on this site against explaining a tea's mouthfeel from its catechin content alone.
Chemically: Flavonols bound to sugars — quercetin, kaempferol and myricetin derivatives.
Where it occurs in the plant
Through the leaf, in bound form with one to three sugars attached. Levels rise with sun exposure, which is one of several reasons a shaded leaf tastes softer than an unshaded one.
What processing does to it
In tea, processing is not a modifier applied to a fixed composition — it is what decides the composition. These are the steps that move this compound, and each links to the step itself.
- Shading — Lowers it
- Suppressed by shading along with the catechins, which is part of why shaded tea reads as smooth as well as sweet.
- Oxidation — Leaves it broadly alone
- Comparatively stable through oxidation, unlike the catechins, so they persist into black tea and contribute to its texture there too.
How brewing brings it out
Extraction rate: Moderate
The attached sugars make them more water-soluble than free flavonols would be, so they extract more readily than their size suggests and are present in cool brews as well as hot ones.
Across infusions: Persistent. Part of why a late infusion can still feel coating even when it has little taste left.
Water: Reliably soluble across the range of water anyone brews with, which is part of why the fine dry astringency they contribute is the one component of a cup that changes least between kitchens.
Leaf, ratio and agitation: Present in small amounts and extracting fully, so leaf quantity moves them almost proportionally with no threshold to work around.
What you can change
- Shorten the steep — this group is why a long steep feels dusty even at low temperature
- Choose shaded tea for a softer texture
Where this gets misdescribed
That total polyphenol content predicts how drying a tea will be. It does not, and this group is a large part of why: a small amount of it changes texture more than a much larger change in catechin level.
Teas this compound defines
Read next
- Catechins — The largest soluble fraction of a green tea leaf, the source of astringency, and the compounds oxidation turns into everything a black tea is.
- EGCG (epigallocatechin gallate) — The most abundant catechin in green tea, and the clearest single demonstration that astringency and bitterness are different things.
- Soluble sugars — Present in small amounts, tasted only faintly, and indispensable as the fuel for every roasted aroma in tea.
What this page does not say
This record describes a group of compounds, their contribution to texture and colour and how they extract. It makes no statement about what they do in a body.
Sources
- TeaHQ editorial synthesis — TeaHQ
This page is TeaHQ’s own synthesis of well-established tea chemistry. No external technical document stands behind it, and that constraint is why there are almost no numbers here: directions, rankings and mechanisms are stated plainly, quantities are not, because a figure nobody can check would look more authoritative than it deserves.