Port wine be labelled as "port" or "Porto". In the United States, wines labelled "port" may come from anywhere in the world, while the names "Oporto", "Porto", and "Vinho do Porto" have been recognized as foreign, non-generic names for port wines originating in Portugal. Port is produced from grapes grown and processed in the demarcated Douro region. The wine produced is then fortified by the addition of a neutral grape spirit known as aguardente in order to stop the fermentation, leaving residual sugar in the wine, and to boost the alcohol content. The fortification spirit is sometimes referred to as brandy but
Wine color and flavor components from the grape skin. Red wine is made from dark-colored grape varieties. The actual color of the wine can range from violet, typical of young wines, through red for mature wines, to brown for older red wines. The juice from most purple grapes is actually greenish-white; the red color comes from anthocyan pigments (also called anthocyanins) present in the skin of the grape; exceptions are the relatively uncommon teinturier varieties, which actually have red flesh and produce red juice. Fermentation of the non-colored grape pulp produces white wine. The grapes from which white wine is produced