Tannin Extraction and Analysis

Problem Definition

Tannin management is central to red wine quality, affecting structure, aging potential, mouthfeel, and color stability. Tannins derive from grape skins, seeds, and stems, each contributing distinct characteristics. The challenge lies in extracting desirable skin tannins while minimizing harsh seed tannins, particularly from unripe or over-macerated fruit. Understanding extraction kinetics, ripeness indicators, and analytical methods enables informed decisions about maceration protocols.

Technical Context

Tannin Sources

Skin Tannins:

Larger polymers (higher molecular weight)
Softer mouthfeel perception
Extracted earlier in maceration
Less bitter than seed tannins
Desirable for wine structure

Seed Tannins:

Smaller polymers (lower molecular weight)
More bitter, astringent
Extracted later (requires alcohol for solubility)
Green/unripe character if under-mature
Proportion increases with extended maceration

Stem Tannins (if whole-cluster used):

Variable depending on lignification
Can be harsh if unripe
Add structure if mature
See Whole-Cluster Fermentation

Extraction Kinetics

Early Maceration (Days 0-3):

Color (anthocyanins) extracted rapidly
Skin tannins begin extraction
Seed tannins minimal
Lower alcohol limits extraction

Mid-Maceration (Days 3-7):

Peak color extraction
Skin tannin extraction continues
Seed tannin extraction begins
Alcohol levels rise (increases solubility)

Extended Maceration (Days 7-21+):

Anthocyanins decline (oxidation, precipitation)
Seed tannin extraction accelerates
Skin tannin proportion decreases
Risk of over-extraction increases

Post-Fermentation Maceration:

Continued seed tannin extraction
Tannin-anthocyanin polymerization
Risk/reward balance

Factors Affecting Extraction

Factor	Effect on Extraction
Temperature	Higher = faster extraction
Alcohol	Higher = increased seed tannin solubility
Cap management	More aggressive = more extraction
SO₂	Increases early extraction
pH	Higher = more extraction
Time	Longer = more extraction

Options and Interventions

Maceration Management

Short Maceration (5-10 days):

Emphasizes fruit and skin tannins
Lower seed tannin contribution
Pinot Noir, delicate varieties
Early-drinking styles

Medium Maceration (10-21 days):

Balance of skin and seed tannins
Standard for quality reds
Cabernet Sauvignon, Merlot

Extended Maceration (21-40+ days):

Maximum tannin extraction
Requires ripe fruit
Nebbiolo, Aglianico traditional
Risk of over-extraction

Extraction Technique

Gentle Approaches:

Pigeage (punchdowns)
Délestage (rack and return)
Submerged cap
Lower temperatures

Aggressive Approaches:

Frequent pumpovers
Rotary fermenters
Higher temperatures
Extended maceration

Ripeness Assessment

Seed Maturity Indicators:

Visual: Green → brown
Tactile: Soft → crunchy
Taste: Bitter → neutral/nutty
Separation: Pulp releases seeds easily

Skin Maturity Indicators:

Easy skin-pulp separation
Soft texture
Full color development
Flavor development

Analytical Methods

Total Phenolics (Folin-Ciocalteu):

General phenolic content
Not tannin-specific
Quick screening

Total Tannins (Methylcellulose Precipitation):

Quantifies tannin-reactive polymers
More specific than Folin
Expressed as catechin equivalents

Tannin Subunit Analysis (Phloroglucinolysis):

Polymer size distribution
Skin vs. seed origin estimation
Research/premium applications

Adams-Harbertson Assay:

Total phenolics, tannins, anthocyanins
Widely used commercial method
Good correlation with sensory

Trade-offs and Risks

Under-Extraction

Characteristics:

Thin structure
Short finish
Limited aging potential
Fresh, simple wines

When Appropriate:

Early-drinking styles
Delicate varieties
Carbonic maceration wines

Over-Extraction

Characteristics:

Harsh, bitter tannins
Astringent mouthfeel
Green character
Imbalanced structure

Causes:

Extended maceration with unripe seeds
Aggressive cap management
High temperatures
Crushing seeds during fermentation

Seed Maturity Mismatch

Problem: Sugar/flavor ripeness achieved before seed ripeness

Solutions:

Shorter maceration
Earlier press timing
Gentle extraction
Accept style limitation

Practical Implications

Variety-Specific Approaches

Tannat (Madiran AOC):

HIGHEST tannin variety
Short maceration (7-14 days)
Micro-oxygenation developed specifically
Blending softens

Nebbiolo (Barolo):

Very long maceration (30-50 days traditional)
Requires fully ripe fruit
Extended aging resolves tannins
Modern: Shorter maceration option

Cabernet Sauvignon (Bordeaux):

Medium-long maceration (14-28 days)
Seed ripeness critical
Blending with Merlot softens
Oak aging integrates tannins

Aglianico (Taurasi DOCG):

High tannin variety
Extended maceration traditional
Very long aging required
Gentle extraction preferred

Tannin-Anthocyanin Interaction

Co-pigmentation and Polymerization:

Tannins bind with anthocyanins
Stabilizes color
Softens both components
Develops during aging

Timing:

Begins during fermentation
Accelerates during barrel aging
Continues in bottle

References

Kennedy, J.A., Saucier, C., & Glories, Y. (2006). “Grape and wine phenolics: History and perspective.” American Journal of Enology and Viticulture, 57(3), 239-248. DOI: 10.5344/ajev.2006.57.3.239
Casassa, L.F. & Harbertson, J.F. (2014). “Extraction, evolution, and sensory impact of phenolic compounds during red wine maceration.” American Journal of Enology and Viticulture, 65(1), 25-42. DOI: 10.5344/ajev.2013.13047
Ribéreau-Gayon, P., et al. (2006). “Handbook of Enology, Volume 2.” Wiley. Publisher Link Publisher Link
Adams, D.O. & Harbertson, J.F. (1999). “Use of alkaline phosphatase for analysis of tannins in grapes and red wines.” American Journal of Enology and Viticulture, 50(3), 247-252. AJEV Link

Last Updated: January 6, 2026