Definition - What does Ripe mean?
Ripe or ripeness is the point in the growing process when grapes have reached their potential maturity. When grapes ripen, sugars increase and acidity will decrease.
For red grapes, they begin to ripen when their skins change from green to red, in a process called veraison. The stems will turn brown and the skins of the grapes will also soften.
WineFrog explains Ripe
The level of ripeness is not the same from one grape to the next or even for the same grape varietal. A ripe grape is not solely determined by its sugar content.
A winemaker will first take field samples of grapes. These are mashed together and the juice is tasted and will undergo laboratory tests to determine whether the grapes are ready to make wine.
A grape is "ripe" when the determined acidity and sugar levels are in balance with one another to create a balanced wine. This can vary from season to season and from grape to grape.