Astringency
Astringency is the dry, puckering, rough sensation tea leaves on the tongue and teeth, a tactile effect of polyphenols binding saliva proteins.
Definition
Astringency is often confused with bitterness, but it is a texture, not a taste. When tea polyphenols such as catechins and theaflavins enter the mouth, they bind to proline-rich proteins in saliva and cause them to precipitate. Saliva loses its lubricating effect, and the tongue, gums and teeth feel dry and rough. Tea's astringency comes mostly from the gallate catechins, EGCG and ECG, and in black tea from theaflavins. It increases with brewing temperature, steep time and leaf quantity, and is higher in unshaded summer leaf and assamica varieties. In moderation astringency is a valued part of tea's structure. In Chinese tasting, a brief astringency that quickly turns into a sweet, moist aftertaste is a mark of quality, part of what is called huigan. Briskness in a good Assam or Kenyan black tea is partly a measured astringency. What tasters object to is astringency that lingers, coats the teeth, and leaves the mouth parched long after swallowing. That usually points to over-extraction, low-quality leaf, or a harsh young sheng pu'er.
In Depth
How to tell it from bitterness: bitterness is detected on the tongue as a taste and can be noticed with the tea held still. Astringency is felt: rub the tongue against the roof of the mouth after swallowing. A dry, sandpaper feeling is astringency.
Reducing it: lower the water temperature by 5-10°C, shorten the steep, or use less leaf. Cold brewing produces markedly lower astringency. Milk reduces it because milk proteins bind the polyphenols before saliva proteins do.
Hard water and some foods can change the perception. Pairing astringent teas with fatty or protein-rich food softens them; drinking them on an empty stomach makes astringency more noticeable. In young sheng pu'er, astringency that softens over five to ten years of storage is one of the main reasons the tea is aged.
See Also
- Tea Tasting
- Tea Polyphenols
- Mouthfeel