Ripeness in viticulture

In viticulture, ripeness is the completion of the ripening process of wine grapes on the vine which signals the beginning of harvest. What exactly constitutes ripeness will vary depending on what style of wine is being produced (sparkling, still, fortified, rosé, dessert wine, etc.) and what the winemaker and viticulturist personally believe constitutes ripeness. Once the grapes are harvested, the physical and chemical components of the grape which will influence a wine's quality are essentially set so determining the optimal moment of ripeness for harvest may be considered the most crucial decision in winemaking.

There are several factors that contribute to the ripeness of the grape. As the grapes go through veraison, sugars in the grapes will continue to rise as acid levels fall. The balance between sugar (as well as the potential alcohol level) and acids is considered one of the most critical aspects of producing quality wine so both the must weight and "total acidity", as well as the pH of the grapes, are evaluated to determine ripeness. Towards the end of the 20th century, winemakers and viticulturists began focusing on the concept of achieving "physiological" ripeness in the grapes-described as a more complete ripeness of tannins and other phenolic compounds in the grapes that contribute to the color, flavor and aroma of wine.

What happens to a grape as it ripens

If ripening is broadly defined as the development of wine grapes, then it could be said that ripening is happening throughout the continuous annual cycle of the grapevine. More narrowly defined, ripening begins at the inception of veraison. At this point (which is normally 40–60 days after fruit set though it may be longer in cooler climates), the grapes are hard and green with low sugar levels and very high levels of mostly malic acids.