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
Phenolic content in wine the methods of production, wine type, grape varieties, ageing processes, the following phenolics can be found in wine. The list, sorted in alphabetical order of common names, is not exhaustive. Phenolic compounds may interact with volatiles and contribute to the specific release of aromas in a wine. Although phenolics are speculated to provide antioxidant benefits from consuming wine, no evidence exists to date that wine phenolics actually have any effect in humans. Phenolic content in wine The phenolic content in wine refers to the phenolic compounds—natural phenol and polyphenols—in wine, which include a large group of several hundred chemical compounds