The Keeping of the Wine Pt.2

The next time you are enjoying a bunch of grapes, notice if there's one that you bite into and it leaves a bitter, dry cotton taste in your mouth. That tastes is caused by a chemical compound found in grape skins called tannins. They're naturally found in grape skins and other vegetation as well. Tannins are only found in red wine because the colour comes from the skin and pulp of a grape so it's all left together for a while during the wine making process. So, leaving the wine to age a while will allow the tannins to mellow. Otherwise you'd have a rather bitter tasting wine that you'd immediately chuck in the bin.