Tannin Management: Mouthfeel, Astringency, and Fining

Tannins are polyphenolic compounds that create the sensation of dryness, grip, and astringency in wine. They bind to proteins on the tongue and in saliva, creating a physical puckering sensation. In the right amounts and in the right form, tannins provide structure, ageability, and complexity. Too much or in the wrong form, and they make wine bitter and harsh.

Types of Tannins in Wine

Grape tannins (condensed tannins / proanthocyanidins)

Skin tannins: Predominantly in the outer layers of the grape skin. Medium-weight polymer chains. The main contributor to wine tannin from red grape fermentation. Extracted during maceration.

Seed tannins: Small, low-molecular-weight monomers. Very astringent, harsh, drying. Extracted particularly under heat and from seeds damaged by aggressive mechanical action (over-vigorous pumping, over-pressing). Should be minimised.

Stem tannins: In fully lignified (ripe) stems: fine, grippy tannins that add complexity. In green, unripe stems: harsh, vegetal, drying. See the whole-cluster article.

Oak tannins (hydrolysable tannins / ellagitannins)

From barrel staves and oak alternatives. Ellagitannins are larger molecules than grape tannins. They integrate more slowly, softening over time with ageing in bottle. They interact with grape anthocyanins to stabilise colour.

The Tannin-Protein Interaction

Tannins bind to proteins through a complex of hydrogen bonds and hydrophobic interactions. In the mouth:

• Salivary proteins lubricate the mouth — salivary mucins prevent friction
• Tannins bind these proteins, removing lubrication
• The tongue drags against the palate — this is astringency

Key insight: Tannin astringency is not just about concentration but about tannin size and shape. Small monomeric tannins (harsh, from seeds) produce rough astringency. Large, polymerised tannins (from skin extraction and ageing) produce a fine, velvet-textured grip. Winemaking decisions influence which form dominates.

How Tannins Evolve in Wine

During fermentation

Temperature drives extraction speed. Warmer fermentation (28°C) extracts tannins rapidly. Cooler (20°C) extracts more slowly and selectively. Cap management (punch down / pump over) determines how much contact between juice and skins occurs.

During ageing

Tannin monomers progressively polymerise — linking into longer chains. This is the chemical basis of wine softening with age:

• Short chains (monomeric, oligomeric): harsh, astringent
• Medium chains (early polymers): firm, structured
• Long chains (late polymers): soft, silky, velvety

Oxygen accelerates polymerisation. This is why barrel-aged reds (micro-oxygenation through staves) soften more quickly than wines in sealed stainless tanks.

Time in bottle continues the process even without oxygen, through acid-catalysed polymerisation. A harsh young Cabernet can become silky after 5–10 years.

Tannin-anthocyanin interactions

Tannins bind with anthocyanins (red colour pigments) to form stable polymeric pigments. These are more stable than free anthocyanins — they don't brown as readily and persist longer in aged wines. Red wine colour after ageing is largely due to these tannin-anthocyanin polymers rather than free anthocyanins.

Extracting the Right Tannins

Maceration length

Short maceration (5–10 days): lighter tannin, more fruit-forward, earlier drinkability Standard maceration (14–20 days): balanced tannin, classic style Extended maceration (30+ days): high tannin, structured wine needing significant ageing

Taste during fermentation daily to assess tannin evolution. When tannins are firm but not harsh, that's often the right moment to press.

Cap management intensity

More aggressive extraction (more pump-overs, more pigeage) produces more tannic wines. Reduce frequency as the wine develops to avoid over-extraction.

Seed management (délestage)

Rack-and-return (délestage) allows seeds to fall out of suspension when the cap is dropped. Reduces seed tannin extraction, which is usually beneficial for smoother, less harsh wines.

Temperature

Cold soak (8–12°C, pre-ferment): extracts colour and soft, anthocyanin-linked tannins without harsh seed tannins. Benefits colour stability without extraction of harsher compounds.

Managing Tannins After Fermentation

Egg white fining

Traditional for red wines. 1–4 egg whites per 225L barrel (beaten to foam, added to wine). Egg white proteins selectively bind the harshest (most astringent) tannin fractions, pulling them out of solution. Effect: softens harsh edges while preserving overall structure. Minimal flavour stripping compared to bentonite.

Gelatin fining

More powerful than egg white. Removes broader range of tannins — risk of over-fining (stripping too much). Often requires a bentonite follow-up to remove excess gelatin.

Casein (milk protein)

Good for oxidation-related browning and some harsh tannin removal. Not vegan.

Micro-oxygenation

Controlled oxygen dosing (µOx systems in commercial wineries) polymerises tannins rapidly in tank, mimicking the gradual oxygen exposure of barrel ageing. Not practical at home scale.

Time and patience

The most reliable and underused fining agent. A young, tannic red that was undrinkable at 6 months may be silky at 3 years. Build ageing time into your planning for structured, high-tannin varieties.

Identifying Tannin Problems