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
Quinta classification of Port vineyards in the Douro Quinta classification of Port vineyards in the Douro The Quinta classification of Port vineyards in the Douro is a system that grades the "terroir" and quality potential of vineyards in the Douro wine region to produce grapes suitable for the production of Port wine. In Portuguese, a "quinta" is a wine producing estate, which can be a winery or a vineyard. While other wine classification systems may classify the winery (such as the 1855 Bordeaux classification), the Douro quinta classification is based upon the physical characteristics of the vineyard. The classification system is run by the "Instituto dos Vinhos do