Harvest (wine) of wine, winemakers would use the sugar and acid levels of the grape as a guide in determining ripeness. Early winemakers tasted the grapes to gauge ripeness. Modern winemakers use a refractometer to measure high sugar levels and °Brix or titration tests (using an indicator such as phenolphthalein) to determine the titratable acidity within the grape. In recent times there has been more of an emphasis on the "physiological" ripeness of the grape, usually in the form of tannins and other phenolics. Currently, tasting is the only way to measure tannin ripeness, which can take experience and skill to do
Classification of wine defined names reflecting the traditional wines produced in the named region. These naming conventions or "appellations" (as they are known in France) dictate not only where the grapes in a wine were grown but also which grapes went into the wine and how they were vinified. The appellation system is strongest in the European Union, but a related system, the American Viticultural Area, restricts the use of certain regional labels in America, such as Napa Valley, Santa Barbara and Willamette Valley. The AVA designations do not restrict the type of grape used. In most of the world, wine labeled Champagne