The pigments are mainly phenols such as anthocyanins, and their colors constitute the color of the wine, and bring their own aroma and delicate taste to the wine. The color in the aged wine mainly comes from tannins. In addition to the contribution of the color of the wine, it also acts on the mouth to produce bitterness, which promotes people's appetite. The tannin content is too high, the bitterness is heavy, and the wine is rough. Tannin also masks the acidity, so red wines are significantly less acidic than white wines because they are rich in tannins. It can be inferred from this:. ['Aged Portuguese wine promotes appetite and its color comes from tannins.', 'Bitter and heavy wines must contain too much tannin.', 'Weak and thin wines must have too low tannin content.', 'Tannin can affect the color of wine and taste and appetite of drinkers.']