There, the grower plants grape varieties which over the years have proven best for his particular soil and climate. The vines start their yearly cycle in April, flower about six weeks later and go on to produce grapes that ripen by fall. Grapes are ready for harvest when they develop the proper balance of sugar and acidity. After they are picked, the grapes are put into vats to begin fermentation, the process that changes grape juice into wine. In the fermentation process, yeast, which forms naturally on the grape, converts the natural sugar of the juice into alcohol and into carbon dioxide that escapes.
Red wine is made by fermenting the juice with their skins.
The skins contain pigment and tannin, and it is these qualities that give red wine its color and long life. Rose is made by fermenting the juice of red grapes with their skins for a short time only. To make white wine, the grapes are pressed and the juice is fermented without the skins. When fermentation is controlled, it will stop automatically after all the sugar has been converted to alcohol. When this occurs, the remaining, or residual, sugar will create a wine that is naturally sweet.