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
Ripeness in viticulture weight from the juice of a single grape or they can use a hydrometer in the winery with the juice from several dozen or hundreds of grape berries. Different countries around the world use various scales to measure the must weight of grape juice. In the United States, New Zealand, and parts of Australia it is measured in degrees brix (symbol °Bx); in Germany (wine) it is degrees Oechsle (°Oe); in France and most of Europe the Baumé scale was used until 1961 and in Austria the Klosterneuburger Mostwaage (°KMW) scale is used. After "veraison" has begun, viticulturists will test