Controlling extraction and phenolic reactions during red winemaking

Understanding Phenolic Extraction in Red Wine Production

This video provides an in-depth exploration of the phenolic extraction process in red wine production, focusing on how phenolic compounds such as tannins and anthocyanins impact a wine’s structure, color, and mouthfeel. Effective management of these compounds during winemaking is crucial for producing high-quality wines.

Key Insights from Recent Research

The presentation draws on recent experimental research in Germany and other wine regions. The goal is to bridge the gap between winemaking and wine science by sharing practical techniques and scientific findings.

Factors Influencing Phenolic Control:

• Temperature, pressure, and maceration techniques: Modern technology has made these variables easier to control.
• Complex variables like sugar, acidity, and phenols: More difficult to manage in real-time and require advanced analytical tools.
• Sensory skills: Winemakers often rely on their intuition alongside lab analysis during fermentation and aging.

The Impact of Vineyard Management on Phenolic Development

The speaker emphasizes the importance of understanding grape ripening and its impact on phenolic content. The development of phenolic compounds in skins and seeds differs from sugar and acidity levels in grape flesh, making them harder to track.

Key Points on Grape Maturity and Phenolic Content:

• Climate variability: Warm vintages accelerate grape maturity, increasing sugar levels and extractable phenols, while cooler vintages slow the process.
• Phenolic maturity vs. sugar maturity: Phenols in the skins and seeds don’t always develop in sync with sugar levels, requiring careful monitoring.

Experiment: Juice-to-Solid Ratios and Their Effect on Wine

The lecture features an experiment on the effect of manipulating the juice-to-solid ratio during fermentation. The study compared early and late harvests, each with different juice-to-solid ratios.

Results of the Experiment:

• Early harvest juice with lower sugar and higher acidity: When combined with later-harvest solids, it produced a wine with better tannin structure and mouthfeel.
• Balance of juice and solids: Critical for creating wines with optimal characteristics.

Winemaking Techniques for Phenolic Optimization

The speaker covers various winemaking techniques designed to optimize phenolic extraction during fermentation and aging.

Key Winemaking Techniques:

• Cold soaking: A pre-fermentation technique that enhances anthocyanin extraction while delaying tannin release.
• Punch-downs and remontage (pump-overs): Cap management techniques that influence tannin extraction and overall wine style.
• Other techniques: Whole-cluster fermentation, delestage, saignée, and extended maceration are also discussed.

The Role of Barrel Aging in Phenolic Development

A significant portion of the lecture is devoted to how barrel aging impacts phenolic evolution in red wine. Oxygen ingress during aging promotes the polymerization of tannins and anthocyanins, improving color stability and mouthfeel.

Key Insights on Barrel Aging:

• Oxygen ingress: Promotes slow oxidation and polymerization of tannins and anthocyanins.
• Acetaldehyde’s role: Facilitates tannin-anthocyanin bonding, improving texture and color stability.
• Storage conditions: Temperature and humidity significantly impact phenolic evolution and oxidation during barrel aging.

Conclusion: Bridging the Gap Between Science and Winemaking

The lecture concludes by emphasizing the need for collaboration between winemakers and wine scientists. Research findings must be effectively applied in wineries to improve wine quality and consistency.

Practical Takeaways:

• Advanced tools: Easy-to-use spectrometers and other technologies can help winemakers measure phenolic content in real time.
• Continuous collaboration: Working together allows both scientists and winemakers to enhance the winemaking process, ensuring better control over wine quality.

This synergy between science and practice is essential for adapting to challenges like climate variability and optimizing red wine production.

A recording of Dominik Durner’s presentation in the in-depth technical meeting “THERE IS NO CONTROL WITHOUT MEASURE: New analytical solutions for monitoring winemaking dynamics” organized as part of the Spoke 7 Lab Village project dedicated to smart agri-food and coordinated by the University of Verona within the Italian Northeastern iNEST-Ecosystem of Innovation Consortium.