Perhaps no other group of plants is known better than the wine grapes. The wine grape is known more for its ability to ferment into wine, than for its desirability as a table grape or a desert grape, because of the thick skin, large seed and a smaller grape size. Some wine grapes contain so much sugar inside the skin, that they will not ferment on the vine after ripening, but will turn into a raisin.
A unique and aesthetic quality of the grape is the obvious capacity for producing so much volume of juice. That grape juice may be used fresh or fermented into famous wines with distinctive aromas and flavors that increases in quality, desirability and value with aging, some wines lasting for centuries. The Roman wine makers poured floating olive oil into the wine bottles to prevent the wine from oxidizing and fermenting further into vinegar. Wine color is determined by which color grape skin is selected for the grape juice to ferment in. If red grape skins are selected as the fermenting medium, then red wine will result, and if white grape skins are selected, then white wine will be produced.