where do the tannins in wine come from
Wine color Red drupe grapes can produce white wine if they are quickly pressed and the juice not allowed to be in contact with the skins. The color is mainly due to plant pigments, notably phenolic compounds (anthocyanidins, tannins, etc.). The color depends on the presence of acids in the wine. It is altered with wine aging by reactions between different active molecules present in the wine, these reactions generally giving rise to a browning of the wine, leading from red to a more tawny color. The use of a wooden barrel (generally oak barrels) in aging also affects the color of the wine.
Merlot The earliest recorded mention of Merlot (under the synonym of Merlau) was in the notes of a local Bordeaux official who in 1784 labeled wine made from the grape in the Libournais region as one of the area's best. In 1824, the word Merlot itself appeared in an article on Médoc wine where it was described that the grape was named after the local black bird (called merlau in the local variant of Occitan language, mèrle in standard) who liked eating the ripe grapes on the vine. Other descriptions of the grape from the 19th century called the variety lou seme doù flube (meaning "the seedling from the river") with the grape thought to have originated on one of the islands found along the Garonne river.[1]