Oechsle scale The mass difference between equivalent volumes of must and water is almost entirely due to the dissolved sugar in the must. Since the alcohol in wine is produced by fermentation of the sugar, the Oechsle scale is used to predict the maximal possible alcohol content of the finished wine. This measure is commonly used to select when to harvest grapes. In the vineyard, the must density is usually measured by using a refractometer by crushing a few grapes between the fingers and letting the must drip onto the glass prism of the refractometer. In countries using the Oechsle scale, the
Phenolic content in wine but "resolve" (through a chemical process called polymerization) into delicious and complex elements of "bottle bouquet" when the wine is cellared under appropriate temperature conditions, preferably in the range of a constant . Such wines mellow and improve with age with the tannic "backbone" helping the wine survive for as long as 40 years or more. In many regions (such as in Bordeaux), tannic grapes such as Cabernet Sauvignon are blended with lower-tannin grapes such as Merlot or Cabernet Franc, diluting the tannic characteristics. White wines and wines that are vinified to be drunk young (for examples, see nouveau wines)