The skin of the grape accounts for 5 to 20% of the total weight of a grape depending on the variety.[28] When grape skin ripens, it contains the majority of the aromatic substances and tannin.[29] These factors become important in winemaking for methods including color extraction or aroma dissolution.[30] Although the skin contains the majority of the tannin, small percentages can be found throughout the grape and during all of its developmental stages.