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
Wine Grapes and original work that is much more extensive in coverage, and also incorporates recent findings from ampelographic research, including DNA profiling of grape varieties. "Wine Grapes" include a catalog listing of 1,368 grape varieties from across the globe including 377 Italian, 204 French and 77 Portuguese wine grape varieties. Coverage includes a listing of synonyms as well as the genetic relationship between varieties derived from DNA analysis. According to Jancis Robinson and José Vouillamoz, "Wine Grapes" includes details about almost 300 previously unpublished relationship between different grape varieties including the extensive family tree of the Pinot grape that includes a