Oechsle Scale - Overview

Overview

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 of the refractometer. In countries using the Oechsle scale, the refractometer will be calibrated in Oechsle degrees, but is an indirect measure, since the refractometer actually measures the refractive index of the grape must.