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
Seibel grapes Seibel grapes Seibel grapes are a group of wine grape varieties which originated with the work of Albert Seibel crossing European grape with American grape species to increase disease resistance. They were planted widely in France during the 1950s but have seen decline in recent years because French wine law proscribes hybrid grapes in appellation wine. The grapes are still commonly used as blending grapes in table wine and mass commercial wines. New Zealand, England, and Canada also have plantings of Seibel grapes. Of great importance is the fact that almost all of Albert Seibel’s hybrid grapes were descended from