Fermentation of the wine begins with the crushing of the grape. Wine juice in itself is clear. Red is made by laceration of the grapes skin. The longer the process the deeper the color. All that is needed to turn grape juice into wine is the natural process fermentation.
Fermentation is the chemical change of sugar to alcohol.
Left to nature, all wines would be dry but that's where the winemaker introduces his or her experience and skill to the process. Barrel bungs to be wiped with a solution of sulphur dioxide. Bottling of Older wines. The Pruning of the Vines. The Racking of the new wine into new barrel s Finish pruning and take cuttings for grafting.