I'm sure you have heard the words "harvest" and "vintage". You may have wondered about these two terms.
The word vintage originates from vendage, which is french for harvest. A 2008 vintage means the grapes were harvested in 2008. People will say a wine is "a good vintage" when the grapes come from conditions that made a good harvest.
What time is a good time to harvest? When does the winemaker know? Why do the dates of the harvest change each year?
The best time to harvest depends on different factors. The winemaker must go by chemical composition and taste. The winemaker must do this across the entire vineyard, not just a single area.
It all goes back to the levels of sugar and acidity in the grapes. These levels will affect the taste and thus the time for harvest.
It is much more complex than what I am explaining, but I'll leave that to the experts. Just understand that there are different measuring scales for the sugar and acidic levels. For example, the name for the sugar measuring scale in America is called Brix.
Once the winemaker determines the time for harvest, they must either harvest by machine or by hand. Harvesting by hand would allow the pickers to pick the best grapes and see the quality of the grapes at that exact moment. Of course for larger vineyards, a machine would do the work faster. I would think a disadvantage for machines would be the inclusion of more dirt and rocks. (maybe i'm wrong on this matter) I would still want workers checking the grapes picked from a machine so they could remove foreign particles.
Destemming is where the stems are removed from the grapes. This is normally done before crushing.
This is just a little bit on harvesting. There is much more to learn about it. If you wish to learn more please purchase the book Exploring Wine.