At this point the juice may be made into sweet wine by having the fermentation process arrested while it still contains sugar or all the sugar may be fermented out of the juice and a dry wine will be produced. The finished wine may then be aged in oak casks for a period of time before bottling, depending on the style of wine being made. Red Wine Red grapes are harvested and brought to the winery. They are fed into a crusher-stemmer machine that tears off the stalks and pumps the broken grapes into a fermentation tank where the juice is allowed to ferment in contact with the skins. This skin contact provides red wine with its colour and tannic character.
Fermentation can go on for up to two weeks, or until all the sugar is used up.
If sugar and yeast is added to finished wine the fermentation process will begin all over again and the carbon dioxide produced, if given no means of escape, will be trapped in the wine. This natural carbonation is the basis of the champagne method of sparkling wine production. The best sparkling wines are those that undergo a second fermentation inside the bottle. The classic sparkling wines made in the Champagne region of France and the great sparkling wines of Spain utilize this method. Let price be your guide, those that utilize the more difficult champagne process tend to cost more than those that do not.