Which phenolic compound found in grape skins and seeds, also found in black tea and hops, gives a drying sensation in the mouth and tends to the back of the mouth and teeth?

• A. Mouthfeel
• B. Acidity
• C. Tannin
• D. Residual sugar

Answer: (C)

Astringency from tannins is the key idea. Tannins are a class of phenolic compounds found in grape skins and seeds, and they’re also present in black tea and hops. When tannins meet saliva, they bind to proteins in your saliva and on your mucous membranes, causing those proteins to precipitate. That interaction shortens the lubricating film of saliva and creates a drying, puckering sensation, often most noticeable toward the back of the mouth and on the teeth. This texture effect is a hallmark of tannins and contributes to the structure and aging potential of wines.

Mouthfeel is a broad texture descriptor, not a specific chemical. Acidity describes a sour taste from acids, and residual sugar refers to lingering sweetness. So the compound responsible for that drying, astringent sensation is tannin.