Although people think of astringent as our or bitter, it is distinct from those tastes. Foods that taste astringent tend to dry the mouth. Persimmons (especially unripe) and tannins in red wines and teas are known for tasting astringent.
This from Wikipedia: Astringency tastes unpleasant to many mammals (including humans), which tend to avoid eating astringent fruit; conversely, birds do not taste astringency and readily eat these fruit. It is thought that fruit astringency gives a selective advantage to some plant varieties because birds are better than mammals at long-distance seed dispersal, often flying a great distance before passing the seeds in their droppings.
The apple wasn’t ripe, so it had a drying, puckering, or astringent taste.
In the upper region they live chiefly on the acid and astringent berries of the guayavita...
Charles Darwin -- The Voyage of the Beagle
Liquid splatters my skin, and the astringent smell of alcohol makes my nostrils flare.
Lauren Oliver -- Delirium
Mayonnaise, for example, is supposed to be evaluated along six dimensions of appearance (color, color intensity, chroma, shine, lumpiness, and bubbles), ten dimensions of texture (adhesiveness to lips, firmness, denseness, and so on), and fourteen dimensions of flavor, split among three subgroups—aromatics (eggy, mustardy, and so forth); basic tastes (salty, sour, and sweet); and chemical-feeling factors (burn, pungent, astringent).