Grape Tannins Come from Pressing.

You will always be able to detect grape tannins to some extent.  Think about it this way.  When you press grapes to release their juice, there will always be a certain amount of friction and heat produced.  In a sense, you are crushing grapes in some fashion to break them apart.  In the past, grapes were normally mechanically pressed by running them through a press that used force.  This in turn would grind the skins, stems (if they were not removed) and seeds mechanically releasing the acids. 

For red wine, this would be ok.  In reds, a certain level of tannins in the finished product will add some character and body. However, in a white wine, grape tannins in high levels would mask some characteristics.  You would not be able to taste the varietal character cleanly.  Imagine taking a good Chardonnay and adding a few drops of vinegar to the wine.  While the acid is different, it still would have the same effect.  The mouthfeel would feel horrible.

Modern times brought over the invention of the bladder press.  I always explain it this way.  Think of placing a large, uninflated balloon into a 5-gallon pail with grapes.  As you expand the balloon, it will take up more space pushing the grapes gently against each other.  Expand it enough and the grapes would be forced against each other in the confined space.  The grapes would break apart gently releasing their juice.  Less force equals fewer grape tannins to let the white varietal components show.

Oak Exposure.

Grape tannins will always be found in wine.  However, not all wines will have oak tannins.  As I explained before, oak tannin can only come from a wine being exposed to oak in some way.  First of all, the winemaker has to make the decision if they wish to have oak in the final wine.  When the wine is exposed to oak, it will pick up the tannins but also some of the aroma and flavor as well.  If I have a delicate white wine, do I want any oak in there?  Maybe not.  However, some whites (such as Chardonnay) will benefit from this.

Once this is decided, how do they expose oak to wine?  There are three major ways that this can be done:

1. Oak pieces / chunks placed into a wine for extraction,
2. The must (grape juice) is fermented in oak barrels,
3. The wine after fermentation is placed into barrels for aging.

In each case, the wine is exposed to oak to let the tannins be extracted.  There are numerous variables here with processes and amounts of oak.  However, the easiest aspect to remember is that the winemaker is looking for a certain level of extraction of tannins to elevate the wine. 

How do you Detect Tannins?

Grape tannins are felt all over the sides of your mouth.  Normally it’s hard to detect them if a wine is made correctly as they would be controlled during the winemaking process.  Would you want the pucker from grape seeds in your finished wine?  Most likely not so the winemaker during pressing will moderate these levels. 

Oak tannins are interesting.  As I stated before, these in strong levels feel like something is coating your teeth.  This tends to be the high end (but I have felt it before).  However, oak tannins can be detected underneath the tip of your tongue.  If you taste a wine that has oak exposure, the underside of your tongue will have a small buzz.  The best way to describe this sensation?  It’s like a weak 9 volt battery touched to the tip of your tongue (and for the record, yes I’ve done it and no I don’t advise it).  However, for us old timers that wanted to know if their Coleco Football game had enough battery juice, we would check it this way.  This buzz, once you dial into it after numerous tastings, will let me know what type of oak was used and how long the wine was exposed to it.

Let’s refer back to the Sauvignon Blanc wine from an earlier article.  You can detect some faint grape tannins since they are masked by high acid.  However, this wine was not exposed to oak in any way so you will not get the buzz on your tongue.