Coupage derives from the French word "couper," meaning "to cut." In the world of wine, coupage refers to a blending wine or a cutting wine that is used to change the taste or color of the primary grape.
Purpose of Blending
The goal of blending wines is to create a new wine that is better than the individual wines alone. Blending changes a specific feature of the wine, such as taste, color or acidity. Blending, however, is not used to improve a poor or mediocre wine by adding a good vintage to a bad.
Cabernet sauvignon, cabernet Franc and merlot are among the preferred grape varieties used as blending wines. Vintners sometimes blend wines using different vintages of the same grape. They also blend based on how the wines were aged to enhance or reduce the effects of wooden barrels, mixing wines aged in new barrels with those from old.
Blending requires attention to detail. Vintners blend wines of the same color -- red grapes with red, white grapes with white. Blending occurs after the wine fermentation process, with each grape variety fermented individually. Vintners base the quantities of blending wines on scientific measures, such as the percentage of sugars in the grapes.