Tannin
Tannin refers to a group of naturally occurring polyphenolic compounds found in the skins, seeds, and stems of grapes, as well as in oak barrels used during wine maturation. In wine, tannins contribute to structure, texture, and longevity, imparting a drying, astringent sensation in the mouth. While more prominent in red wines due to extended skin contact during fermentation, tannins also play a subtle role in certain white wines and rosés. They are a defining characteristic of many age-worthy wines and influence both flavour perception and the ageing process[1].
Characteristics
Tannins are a class of phenolic compounds present in various plant tissues, notably in grape skins, seeds, and stems. In winemaking, they are extracted primarily during fermentation, especially when the grape must is in contact with the solid parts of the fruit. Their chemical structure allows tannins to bind with proteins and other molecules, producing the characteristic astringency or drying sensation in the mouth[2].
In wine, tannins contribute to body, texture, and structural balance. Their presence can influence colour stability and protect against oxidation. Younger wines tend to show more aggressive tannic grip, which can soften over time through polymerisation reactions during ageing[3].
The perception of tannins varies with concentration, type, and interaction with other wine components, such as acidity and alcohol. Sensory descriptors range from “chalky” and “grippy” to “silky” and “firm”[4].
Relevance in Wine
Tannins play a critical role in the structure, ageability, and mouthfeel of red wines. They form part of the wine’s backbone, lending firmness and complexity that support long-term maturation in bottle. In some cases, tannins interact with anthocyanins (colour pigments) to stabilise colour, particularly in red wines[5].
The level and quality of tannin extraction can be influenced by grape variety, vineyard practices, harvest timing, and winemaking choices, including maceration techniques and fermentation temperature[6].
In white wines, tannins are generally present at much lower levels but may still appear when grapes are pressed with stems or when oxidative handling or oak ageing is used. Tannins from oak barrels – particularly ellagitannins from new oak – can supplement grape tannins, contributing to the wine’s phenolic profile and enhancing its resistance to oxidation[7].
Occurrence
Tannins are present in varying degrees across all red wine–producing regions, but their expression is closely tied to grape variety and growing conditions. Grapes such as Cabernet Sauvignon, Nebbiolo, and Tannat are noted for their high tannin potential, while varieties like Pinot Noir typically exhibit softer, more delicate tannic structures[8].
Climate also influences tannin development. Warmer regions often produce riper tannins with rounder textures, whereas cooler climates may result in greener or more angular tannins if phenolic ripeness is not achieved[9].
In modern viticulture, careful canopy management and harvesting decisions are employed to optimise tannin maturity in the vineyard. Meanwhile, winemakers in both traditional and New World regions adapt their extraction techniques to reflect regional styles, desired ageing potential, and consumer preferences.
Application
Tannins are primarily extracted during fermentation and maceration, where contact between grape skins, seeds, and stems influences the final wine structure. Winemaking decisions—such as fermentation temperature, cap management, and length of skin contact—play a crucial role in how much tannin is extracted and how it integrates into the wine[10].
Tannins also enter wine through ageing in oak barrels. Oak contains ellagitannins, which contribute additional structure and ageing potential, as well as sensory effects such as bitterness and astringency[11]. The impact of oak tannins is moderated by the type of oak used (e.g., French vs. American), the toast level, and whether the barrel is new or previously used.
Fining agents, such as egg whites or casein, may be employed to reduce excessive tannin levels in young wines. In contrast, extended maturation—either in barrel or bottle—can lead to polymerisation of tannins, softening their texture and reducing astringency over time[12].
Examples
Tannin expression varies widely by grape variety. Thick-skinned red grapes such as Cabernet Sauvignon, Nebbiolo, and Tannat are known for producing wines with high tannin content[13]. These wines often benefit from ageing to soften the astringency and integrate the structure.
In contrast, thinner-skinned varieties such as Pinot Noir and Gamay typically result in wines with lower tannin levels. Similarly, white wines are generally low in tannins, although exceptions exist—particularly in the case of skin-fermented white wines or wines aged in new oak.
Tannins are also a key factor in the ageing potential of wine. Wines with firm but balanced tannic structure can evolve over decades, as seen in examples from Bordeaux, Barolo, and certain Napa Valley Cabernet Sauvignons[14].
See also
References
- ↑ Wine Folly, "Tannins in Wine: What Are They?", winefolly.com (English original)
- ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015, p. 705 (English original)
- ↑ Goode, The Science of Wine: From Vine to Glass, University of California Press, 2014, pp. 101–104 (English original)
- ↑ Peynaud, The Taste of Wine, Macdonald & Co, 1987, pp. 74–76 (French original)
- ↑ Vivas & Glories, “Role of tannins in wine structure and aging”, Vitis, Vol. 33, No. 1, 1994 (English original)
- ↑ Delteil, Le goût du vin expliqué par la science, Éditions Féret, 2012, pp. 93–96 (French original)
- ↑ White, Kelli, “Oak and Wine”, GuildSomm.com, accessed August 2025 (English original)
- ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015, p. 700 (English original)
- ↑ Goode, The Science of Wine: From Vine to Glass, University of California Press, 2014, pp. 120–122 (English original)
- ↑ Goode, The Science of Wine: From Vine to Glass, University of California Press, 2014, pp. 115–118 (English original)
- ↑ Peynaud, The Taste of Wine, Macdonald & Co, 1987, pp. 68–70 (French original)
- ↑ Vivas & Glories, “Role of tannins in wine structure and aging”, Vitis, Vol. 33, No. 1, 1994 (English original)
- ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015, p. 681 (English original)
- ↑ Goode, The Science of Wine: From Vine to Glass, University of California Press, 2014, pp. 144–145 (English original)