The content of sugar as the main component in the grapes is expressed by must weight in KMW (Austria) or Oechsle (Germany). In the two countries, the sugar content in the berries is, so to speak, a criterion for the predicate wine grades. The sugar in the grape must is the basis for fermentation, during which a conversion to alcohol and carbon dioxide takes place. Above a certain alcohol content, the yeasts die off and stop fermentation.
The upper limit of the possible alcohol content is about 16 to 18%, when using turbo yeasts during fermentation up to about 20% vol. The associated lower limit of residual sugar in the wine is usually about 0.1 to 0.2 g/l. There is no wine that contains no sugar at all. The phenomenon that the subjective perception of sweetness in wine can differ greatly from the analytical values depending on the amount of other substances is described under the keyword sweet.