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
Quinta classification of Port vineyards in the Douro that the wines that were available were of high quality and not something that could tarnish the reputation of the Douro. Over the years the system of licensing growers turned into a rating classification operated by the IVDP. The system only pertains the production of Port. A quinta that is growing grapes for both Port and table wines, can do whatever they like with the grapes destined for table wine production regardless of its classification rating. Each year the IVDP classifies and rates the vineyards on an A-F scale with A being the highest level. A quinta's rating will dictate