Tannins for wine production
Natural antioxidants to enhance the properties of wines
Tannins are one of the main constituents of wine. In particular red wines, obtained by maceration of the grape skins which contain them in large quantities. These types of tannins are endogenous as they originate from the grapes and its components (seeds and stalks).
Each grape variety has its own tannic profile, which can be appreciated both in quantitative and sensory terms.
Tannins are phenol compounds (aromatic alcohols) with very complex chemical structures and molecular weights between 500 and 3,000 Dalton. They are commonly present in the plant kingdom, such as in:
- Coffee.
- Tea (especially green tea).
- Cocoa.
- Liquorice.
- Artichokes.
- Persimmons.
- Strawberries.
- Walnuts.
- Peanuts.
- Almonds.
- Chestnuts.
- Beans.
- Grapes (obviously).
Tannins are natural products from a botanical source, used in enology to reinforce the natural action of tannins present in the wine (endogenous).
Hydrolysable tannins
The hydrolysable tannins are further divided into gallic and ellagic tannins. The first, the gallotannins release glucose and gallic acid by hydrolysis in low ambient pH. They are mainly extracted from Tara (Caesalpinia spinosa) and gallnuts (Quercus infectoria and Rhus semialata) and they present a creamy or yellowish color. The gallic tannins are not very astringent and have a bitter taste.
The ellagitannins, made from ellagic acid glycosides, are one of the components of oak wood (Quercus robur, Quercus petraea and Quercus alba) and chestnut wood (Castanea sativa). They have a darker color compared to the gallotannins. The ellagic tannins are also less astringent and they have a distinctive wood scent. Ellagitannins are not present in wine unless transferred from the wood of the barrels.
Condensed tannins
The condensed tannins have a reduced astringent power and a high ability to release the aromatic precursors present in wines. Condensed tannins are divided into proanthocyanidin and profisetinidin. Proanthocyanidins are naturally present in grapes (Vitis vinifera) consisting of various flavonoids which release anthocyanins and other insoluble molecules when they are treated with acid hydrolysis. They are mainly diffused in the skins and seeds of grape, and therefore you can find them in red wines. Profisetinidins are extracted from the quebracho wood (Schinopsis lorentzii) and black wattle (Acacia mearnsii).
