Harvesting is the first step in the wine making process and an important part of ensuring delicious wine. Grapes are the only fruit that have the necessary acids, esters, and tannins to consistently make natural and stable wine. Tannins are textural elements that make the wine dry and add bitterness and astringency to the wine.
The moment the grapes are picked determines the acidity, sweetness, and flavor of the wine. Determining when to harvest requires a touch of science along with old fashioned tasting. The acidity and sweetness of the grapes should be in perfect balance, but harvesting also heavily depends on the weather.
Harvesting can be done by hand or mechanically. Many wine makers prefer to harvest by hand because mechanical harvesting can be tough on the grapes and the vineyard. Once the grapes are taken to the winery, they are sorted into bunches, and rotten or under ripe grapes are removed.