Wine Ingredients - Tannin
Most of you may be familiar with tannin as a structural and mouthfeel component of wine, but did you know it's also a fairly common wine ingredient?
Tannins can be used at just about any point in the winemaking process. They come from a few sources-- grapes themselves, oak, chestnut, nut galls, and other, rarer woods. You can find them in liquid or powdered forms. Their uses in wine are varied, and can be different dependent on their source. Regardless, they all protect against oxidation, which helps boost the longevity of the wine.
To this end, they can be added to white juice or wines. They may also be added to bind up with off aroma compounds. In the case of grapes that are somewhat moldy, tannin can be useful in binding with certain fungal enzymes that can speed up oxidation and browning.
For red wines, tannin added early in the fermentation process is considered "sacrificial." You add some to protect the color of the wine, giving proteins and other particles in the fermenting must something to bind to, rather than those already present in the grapes, thus leaving more of the grapes' naturally occuring tannin for the aging process. There's debate as to whether this strategy truly works. To be sure, though, a tannin cannot add color to a wine that is already weak in it.
Tannins can also be added prior to barreling down, while aging, or just prior to bottling. These tannins can be incorporated to help refresh the aromas of tired wines, add a subtle aroma or mouthfeel component (such as chocolate or caramel), or to give a bit more structure to the wine. They should never be used in a way that substantially alters a wine. They're a tool for refining, not for changing the character entirely. And before any addition, there's no substitute for a bench trial-- setting up a specific volume, dosing in the tannin, and tasting to see what works best for the wine.
And when in doubt, you can always ask a technical sales representative what they might recommend. These folks are usually former winemakers themselves, and want you to come away with a better understanding of the tools, as well as a nice wine.