The must weight provides a lot of information about the wine’s quality to be expected. It is measured in degrees Oechsle. The potential alcohol content can be derived from this.
The must weight compares the specific weight ratio of one litre of must to that of water at 20° C, i.e. the specific density of the must. If the weight ratio is e.g. 1.076 the must displays 76 degrees Oechsle. Above all, the must weight results from the sugar content. The maximum potential alcohol content can be derived from this.
By means of must concentration water in small amounts can be withdrawn from the must. The remaining ingredients concentrate and allow for more high-quality wines. However, the procedure is very expensive and is only used for top wines in Auslese quality.
Different minimum must weights for individual grape varieties and winegrowing regions provide only a minimum standard. Many wine growers set significantly higher standards within their own wineries.
(Source: German Wine Institute, www.deutscheweine.de as of 5 July 2011)