Tannins are a cornerstone of a wine's character, providing the structure and longevity that define a high-quality vintage. For winemakers, managing tannins is a crucial part of the craft, dictating everything from a wine's aging potential to its texture on the palate. While most red wines naturally gain tannins from extended contact with grape skins, seeds, and stems, winemakers can intentionally add oenological tannins to achieve specific stylistic goals. The decision to supplement tannins can address imbalances in a low-tannin vintage, enhance color, or add complexity and nuance.
The Role of Tannins in Wine
At their core, tannins are a group of natural phenolic compounds found throughout the plant kingdom. In wine, they are primarily responsible for two sensory effects: astringency and bitterness. The drying, puckering sensation is a result of tannin molecules binding with proteins in your saliva, causing them to precipitate. This textural component, or mouthfeel, is a vital aspect of a wine's body and structure.
- Enhancing Structure and Mouthfeel: Adding tannins can increase a wine's perception of weight, providing a firmer backbone and richer body. This is especially useful for wines made from thin-skinned grapes or those from less ripe harvests.
- Protecting Against Oxidation: Tannins are powerful antioxidants that protect the wine from oxygen's damaging effects. This is essential for long-term aging, as it allows the wine to mature slowly and develop complex flavors without becoming prematurely tired or brown.
- Stabilizing Color: For red wines, tannins help stabilize color by forming complexes with anthocyanins, the pigments that give red wines their hue. This prevents the color from fading or browning over time and maintains the wine's vibrant appearance.
- Fining and Clarification: Tannins naturally bind with proteins and other unstable compounds in the wine, causing them to settle as sediment. This can be used deliberately as a fining agent to clarify the wine, resulting in a cleaner, more polished finish.
- Adding Complexity: Beyond texture, tannins can contribute their own nuanced flavors and aromas, especially those derived from oak. Winemakers can use different types of tannins to impart notes of vanilla, spice, or smoke, depending on the source.
How Winemakers Add Tannins
Winemakers utilize a variety of techniques to add tannins, and the timing of the addition is often as important as the type of tannin used. Common sources include:
- Oak Barrels: Aging wine in oak barrels is a traditional method of imparting tannins, particularly ellagitannins. New oak contributes more tannins and can add woody, spice, and vanilla notes, while older barrels offer a more subtle integration.
- Oak Chips, Staves, or Powder: These products offer a cost-effective and controllable way to add oak-derived tannins during fermentation or aging. Winemakers can select specific products to achieve desired flavor profiles.
- Commercial Tannin Powders: Oenological tannin products are extracted from various botanical sources, including grape skins, seeds, and exotic woods like quebracho. They are formulated for specific purposes, such as color stabilization or enhancing mouthfeel.
Timing of tannin additions is flexible. They can be added before fermentation to protect color and aid yeast, during fermentation to enhance extraction, or during aging and finishing to build structure and refresh a tired wine.
Comparison of Tannin Sources
| Feature | Grape-Derived Tannins | Oak-Derived Tannins | Commercial Tannin Powders |
|---|---|---|---|
| Source | Skins, seeds, and stems of grapes | Wood of oak barrels, chips, or staves | Extracts from grapes, oak, and other woods (e.g., quebracho, citrus) |
| Flavor Contribution | Astringent, often bitter, and can be perceived as 'grippy' or 'chewy' | Adds complex flavors like vanilla, toast, smoke, and spice | Specific products are formulated for targeted effects, from enhancing fruit to masking green character |
| Mouthfeel | Contributes to the wine's intrinsic structure and body | Adds a fine-grained or grainy texture | Offers specific mouthfeel enhancements, from soft to robust |
| Function | Protects grapes and contributes to natural structure | Influences flavor, adds structure, and aids in color stability | Provides targeted solutions for structure, color, or oxidation issues |
| Timing | Extracted naturally during maceration and fermentation | Leached into wine during barrel aging | Added at various stages: pre-fermentation, mid-fermentation, or prior to bottling |
The Importance of Tannin Balance
The goal of adding tannins is not to create an overpowering, mouth-drying wine but to achieve balance. Expert winemakers use tannins to complement a wine's fruit, acidity, and alcohol content, creating a seamless and complex profile. Over time, as wines age, tannins naturally polymerize—binding into longer chains that fall out of solution as sediment—which softens the astringency and results in a smoother, more elegant texture. This is why bold, tannic red wines often require years of aging to reach their peak. A well-managed tannin profile is often a marker of a truly great, long-lived wine.
For more detailed technical information, the International Organisation of Vine and Wine (OIV) provides a comprehensive document on oenological tannins.
Conclusion
Adding tannins to wine is a deliberate and strategic process that gives winemakers precise control over a wine's structure, aging, and sensory characteristics. By selecting specific tannin sources and timing their addition carefully, they can enhance mouthfeel, stabilize color, and protect the wine from oxidation. Whether derived naturally from the grape itself or supplemented with commercial preparations, tannins are an indispensable tool in the cellar, proving that a balanced, complex wine is often a product of artful tannin management.
