Have you ever sipped a wine and immediately experienced a drying sensation in your mouth? That astringent sensation, generally associated with red wines, is associated with tannins.

Tannin is a chemical compound (polyphenol) that occurs naturally in the skin, seeds and stems of grapes. It can also be found in tea leaves, nuts with skins (e.g., almonds and walnuts) and dark chocolate, just to name a few.

Red wines are generally the ones that are highly tannic. This is because the process of making red wine involves leaving the grape skins, seeds and stems in contact with the juice of the grape during fermentation as shown in the photo.

But, tannic compounds also come from wood. So, barrel aging of wines can introduce yet another source of tannin.

Tannin is what gives a wine its complexity and depth of character. Without tannin, the wine would be 'watery,' 'thin' or 'flabby.' And, tannin is a great defender of oxidation. So, it defends against the small amounts of oxygen that gets introduced into a barrel or bottle that could otherwise spoil the wine.

With time, tannins are also responsible for producing that wonderful silky-smooth sensation in wines. The tannin compound actually chemically changes with time causing them to feel smoother and less harsh. Cabernet Sauvignon is the king of tannin and, when young, can have big tannins that can be described as 'rough' or 'dusty.' But with age the tannin ‘softens’ yielding the smooth sensation.

So, there’s a quick overview of the second fundamental trait of a good wine - Tannin. It works in conjunction with the other fundamental traits to add balance, complexity, and structure to wine.

Next time we’ll look at alcohol which is the third fundamental trait. Cheers!