Colour and Cooking: Tannins

Tannin is usually thought of as something present in tea, which is quite correct. However, the term has a more general application, referring to a whole group of substances which are related to the flavonoids but distinguished by the fact that they combine an astringent quality with a tendency to produce dark hues such as blackish-blue and blackish-green. They are generally what give unripe fruits an astringent taste. As the fruits ripen, they cease to have this effect. Green persimmons contain an especially large amount of tannin, which is why they have a markedly astringent, puckery taste. When the persimmons ripen, the membranes enveloping the cells in which the tannin lurks become hard and insoluble and this taste ceases to be evident.