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 a bottle of cooking wine, which may be opened and used occasionally over a long period of time. In other countries sherry wine is used for cooking. Fortified wines resist spoilage, as their alcohol content is too high to permit bacterial growth. A vintage wine is one made from grapes that were all, or primarily, grown in a single specified year, and are accordingly dated as such. Consequently, it is not uncommon for wine enthusiasts and traders to save bottles of an especially good vintage wine for future consumption. However, there is some disagreement and research about the significance of