Show me some skin
Today we're talking about skin. Grape skin, to be precise. And more specifically, something IN the grape skin - tannin.
It's another one of those wine terms you hear bandied around all the time. 'Oh, this Cabernet is so tannic', or 'gentle, silky tannins on this Pinot Noir'. What does it actually mean, though?
The very simple answer, as I've made reference to above, is that tannin is a substance found in grape skins. It's sometimes used in the singular, sometimes in the plural. To be a little more scientifically accurate, as explained in detail in this comprehensive article by wine writer Jamie Goode, tannins are 'polyphenolic compounds that bind to and precipitate proteins.'
Why do we have tannin in wine? In most white wine production, tannin is irrelevant, as the skins and juice are separated from each other right at the beginning of the fermentation process. In red winemaking, however, skins and juice are kept together during fermentation in order to extract colour (slice open a red/black grape and you'll see that the juice inside is clear - the colour all comes from the skins).
Through this 'extraction' process, tannin is also extracted into the fermenting wine. That's why red wine has tannin and white doesn't. There are differing levels of tannin depending on the red wine, however - thicker-skinned grape varieties like Cabernet Sauvignon and Shiraz have more than Pinot Noir, and it's also dependent on how much is extracted during winemaking.
How do we detect tannin in wine? First, it has a bitter taste. Second, it can be detected texturally as well, since it binds to proteins in your saliva and dries your mouth out, giving a rough feel to your gums and cheeks which can be quite unpleasant if the wine is very tannic.
You may well be asking me at this point 'but Anne, why would I want something unpleasant in my wine?!' Fair point! If you carry out a little experiment, however, you'll notice that with the right food pairing, a tannic wine can work brilliantly. Just as tannin binds to protein in your saliva, it also binds to protein in food.
Take cheese, for example. Try a tannic red wine alone, then try it again after enjoying a bite of cheese, and you'll notice that the second time you taste the wine it is gloriously smooth and fruity, without a hint of bitterness or roughness. It also has the added bonus of cleansing your palate so that you can taste that next bite of cheese all the better - similar to acidity, which I wrote about in a previous post.
Tannin also assists in the ageing process of wine, since it has antioxidant properties which protect wine from the ravaging effects of oxygen over time. This is why wine collectors tend to cellar red wines for longer than whites.
So there you go: a brief introduction to tannin in wine. If you have time this week, get hold of a tannic red wine (Italian reds like Chianti are great for this) and do the cheese experiment - you'll be amazed at the effect you notice on your palate.