Brix very similarly to sucrose with respect to specific gravity as a function of concentration, or compounds which are present in small amounts (minerals, hop acids in wort, tannins, acids in must). In any case, even if °Bx are not representative of the exact amount of sugar in a must or fruit juice they can be used for comparison of relative sugar content. As specific gravity was the basis for the Balling, Brix and Plato tables, dissolved sugar content was originally estimated by measurement of specific gravity using a hydrometer or pycnometer. In modern times, hydrometers are still widely used, but
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 According to Jancis Robinson and José Vouillamoz, "Wine Grapes" includes details about almost 300 previously unpublished relationship between different grape varieties including the extensive family tree of the Pinot grape that includes a