The visual perception of a great red wine is often the first indicator of its quality and aging potential. However, a fundamental thermodynamic paradox exists: at the typical pH of wine (3.2–3.8), the colored form of anthocyanins (the flavylium cation) is unstable and tends to transform into colorless forms.
Why, then, do great reds maintain a vibrant color? The answer lies not simply in the quantity of pigment, but in complex molecular dynamics: copigmentation in young wines and polymerization in aged ones.
In this article, we analyze how the winemaker can govern these processes using the right tannins from the EVER range and the correct supporting analyses.
copigmentation. One can imagine this process as a molecular “sandwich”: a cofactor—a colorless, planar organic molecule—associates with the anthocyanin, shielding it from water attack and preventing discoloration.
Classification of Cofactors
It is fundamental to note that not all phenols are equal cofactors. Studies by Boulton, confirmed by Versari, indicate a hierarchy of effectiveness based on planarity and electron density:
- High efficacy: flavonols (such as quercetin) and hydroxycinnamic acids.
- Medium efficacy: catechins, Epicatechins (flavan-3-ol monomers).
- Low efficacy: polymeric tannins, whose steric hindrance prevents the formation of the perfect “sandwich.”
A crucial datum emerging from Versari’s study is that copigmentation in young wines correlates strongly with anthocyanin content, but not with total tannin content. This clarifies why the indiscriminate addition of tannins does not automatically lead to an increase in color.
From copigmentation to polymerization: the role of oxygen.
Copigmentation is a reversible physical phenomenon that diminishes over time. True longevity (“Aging Potential”) is instead built through stable covalent bonds. In this process, oxygen acts as an initiator: it oxidizes ethanol, producing acetaldehyde, which functions as a molecular “bridge” between tannins and anthocyanins.
But who is the typical consumer?
An analysis reveals that in the United Kingdom, one of the most mature markets, 49% of consumers choose these products to avoid the effects of alcohol, while 36% are motivated by taste and 30% by the lower calorie content. (Source: Nomisma Wine Monitor based on NielsenIQ data)
Methodological update: towards a new analytical standard
To evaluate aging potential, historical methods such as Somers’ show evident limits, often overestimating the polymeric fraction and failing to distinguish between stable and unstable polymers.
For modern longevity management, we suggest two approaches:
- Adams Method (Harbertson-Adams): utilizes protein precipitation (BSA) to simulate astringency in the mouth. It is fundamental because it distinguishes between SPP (Small Polymeric Pigments – short/unstable) and LPP (Large Polymeric Pigments – long/stable). A high LPP content is the best predictor of longevity.
- Boulton Method: indispensable at the end of fermentation. It isolates copigmentation via dilution. If the value is low (<25-30%), the wine risks losing color through precipitation: it is the time to act.
Furthermore, HPLC methods are under development capable of separating the different polymeric fractions of tannins and evaluating which are truly resistant to SO₂ (Versari et al.).
Which tannin to choose?
The study by Gambuti et al. on Aglianico wine provides crucial data for understanding how the choice of enological tannin influences the oxidative mechanisms described above.
Oxygen Consumption Kinetics (OCR) and Acetaldehyde Production
The experiment monitored oxygen consumption and acetaldehyde production in wines treated with 30 g/hL of different tannins during 4 saturation cycles.
Data Analysis:
- Tea Tannins (Scavenger): Consume oxygen extremely rapidly (+112%) but produce little acetaldehyde. They protect against immediate oxidation but inhibit the formation of stable color.
- Ellagitannins (Catalysts): Show moderate oxygen consumption (+35%) but the highest accumulation of acetaldehyde (13.5 mg/L, +27% vs control), creating the ideal environment for anthocyanin-tannin condensation.
- Condensed Tannins (Structuring): Essential for building structure (LPP) and conferring softness.
Varietal differences: every grape has its own equilibrium.
Predisposition to longevity is a varietal trait. Let us observe the structural differences between key varieties:
- High Structure Cluster (Sagrantino, Aglianico): Have an excess of tannins. Require oxygenation (MOX) to polymerize the excess structure.
- High Color Cluster (Teroldego): Record anthocyanins but intermediate tannins. Benefit from the addition of enological tannins to fix color that would otherwise precipitate.
- Low Profile Cluster (Corvina): Low phenols. Require techniques such as drying (appassimento) to concentrate solutes.
The Sangiovese Case and the “Myth” of Terroir.
Sangiovese deserves a separate discussion. Analysis has shown enormous intra-varietal variability, often superior to territorial differences. Although samples from Romagna tend to have total phenols slightly higher than those from Tuscany (~2100 vs ~1900 mg/L), the profiles are superimposable.
Insight: the longevity of Sangiovese depends more on agronomic management (yields per hectare) and cellar technique than on genetics or geographical zone. PCA classification showed an overlap between the two zones, indicating that winemaking technique can mask the territorial effect.
Operational recommendations for the cellar: EVER Solutions.
To govern the delicate balance between anthocyanins and tannins, theory is not enough: a precise action protocol is needed.
Ever solutions are inserted in a targeted manner into the different phases of winemaking to support the color, structure, and longevity of red wines.
From maceration to aging, the use of tannins with specific functions allows for:
- protecting color in the initial phases,
- favoring stable polymerization during evolution,
- modulating the perception of astringency and volume on the palate.
Check out Ever solutions here
Conclusions and operational protocol
The integrated analysis of the research cited in this article leads to defining a scientific protocol for the management of longevity and color.
- Fermentation: monitor the Boulton Index. If copigmentation is < 30%, add cofactors.
- Aging: use Ellagitannins to fix color via acetaldehyde; avoid Tea tannins if looking for long-term stability.
- Analysis: monitor the LPP/SPP ratio (Adams Method) as the true indicator of evolution towards longevity.
In conclusion, red wine longevity is the result of a complex balance between pigments, tannins, and oxygen. Knowing these mechanisms allows for orienting technical choices from the very first phases of winemaking, enhancing varietal characteristics and improving chromatic stability over time. Through targeted tannin management and accurate control of phenolic evolution, it is possible to design wines that are more stable, harmonious, and long-lived.
Bibliographic References.
1 Boulton, R. (2001). The copigmentation of anthocyanins and its role in the color of red wine: A critical review. American Journal of Enology and Viticulture , 52(2), 67-87.
Cheynier, V. (2003). Il colore dei vini rossi. Vinidea.net , 2(4).
Versari, A., Boulton, R. B., & Parpinello, G. P. (2008).
A comparison of analytical methods for measuring the color components of red wines. Food Chemistry , 106(1), 397-402.
Picariello, L., Rinaldi, A., Forino, M., Errichiello, F., Moio, L., & Gambuti, A. (2020).
Effect of Different Enological Tannins on Oxygen Consumption, Phenolic Compounds, Color and Astringency Evolution of Aglianico Wine.
Molecules , 25(20), 4607.
Giacosa, S., Parpinello, G. P., Río Segade, S., Ricci, A., Paissoni, M. A., Curioni, A.,… & Rolle, L. (2021).
Diversity of Italian red wines: A study by enological parameters, color, and phenolic indices. Food Research International , 143, 110277.
Tchabo, W., Ma, Y., Kwaw, E., Zhang, H., Xiao, L., & Apaliya, M. T. (2018).
Statistical interpretation of chromatic indicators in correlation to phytochemical profile of a sulfur dioxide-free mulberry (Morus nigra) wine submitted to non-thermal maturation processes. Food Chemistry , 239, 470-477.
Harbertson, J. F., Picciotto, E. A., & Adams, D. O. (2003).
Measurement of polymeric pigments in grape berry extracts and wine using a protein precipitation assay combined with bisulfite bleaching. American Journal of Enology and Viticulture , 54(4), 301-306.
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