What are the EU legal limits for total SO₂ in conventional wines?
- Red wines: 150 mg/L
- White and rosé wines: 200 mg/L
- Sweet wines: Higher limits depending on sugar levels (e.g., 300 mg/L for >5 g/L residual sugar).
What are the EU legal limits for total SO₂ in organic wines?
- Red wines: 100 mg/L
- White and rosé wines: 150 mg/L.
What is free SO₂, and why is it important?
- The active antimicrobial and antioxidant form of SO₂.
- Includes molecular SO₂, bisulfite, and sulfite.
- Protects wine from oxidation and microbial spoilage.
What is molecular SO₂, and what is its desirable range?
- Molecular SO₂ is the aromatically volatile form of free SO₂.
- Desirable range: 0.5–0.825 ppm for microbial stability.
How does pH affect molecular SO₂?
- Lower pH increases the effectiveness of molecular SO₂.
- At pH 3.2, molecular SO₂ is more active compared to pH 3.8.
What are the EU limits for volatile acidity (VA) in wines?
- Red wines: 1.2 g/L (acetic acid)
- White and rosé wines: 1.08 g/L (acetic acid).
What are the key roles of volatile acidity in wine?
- Byproduct of microbial activity during fermentation.
- Excess VA leads to vinegar-like aromas, indicating spoilage.
What is tartaric acid, and why is it used?
- Used for acidification in warm climates with low natural acidity.
- Helps stabilize wine pH and improves balance.
What is Dimethyl Dicarbonate (DMDC), and when is it used?
- DMDC is an antimicrobial agent.
- Typically used in sweet wines with >5 g/L residual sugar.
- Added before bottling to ensure sterility.
What are the functions of sulfur dioxide (SO₂) in winemaking?
- Acts as a preservative to prevent oxidation.
- Provides antimicrobial protection.
- Enhances wine freshness.
What is bentonite, and what does it do?
- Bentonite is used as a processing aid for protein stabilization in white and rosé wines.
- It leaves no residual traces in the final wine.
What are casein and gelatin, and how are they used in winemaking?
- Used as fining agents to remove phenolic compounds and improve clarity.
- Declared on labels only if residual traces are allergenic.
What is activated carbon used for in winemaking?
- Removes off-flavors or discoloration from wine.
When must SO₂ be declared as an allergen on labels?
- When levels exceed 10 mg/L, it must be labeled as ‘Contains Sulfites.’
Why are molecular SO₂ levels critical for microbial stability?
- Molecular SO₂ is the most effective form of SO₂ for inhibiting microbial growth.
- Its activity depends on maintaining a low pH in the wine.
What is the maximum allowable SO₂ for sweet wines with >5 g/L residual sugar?
- Typically up to 300 mg/L, depending on EU regulations.
What are the challenges of reduced SO₂ in organic wines?
- Balancing reduced SO₂ use while maintaining microbial stability.
- Requires alternative methods, such as lower pH levels and enhanced hygiene.
Why is VA (volatile acidity) monitored closely in wine production?
- Excess VA indicates spoilage and can lead to vinegar-like aromas.
- Maintaining VA within legal limits is critical for wine quality.
How does pH influence winemaking decisions?
- Lower pH enhances the effectiveness of molecular SO₂.
- pH adjustments can help maintain stability and prevent microbial spoilage.
What role do QR codes play in modern EU wine labeling?
- Provide extended ingredient and nutritional details.
- Allow batch-specific updates (e.g., changing vintage details).
- Must exclude marketing or promotional content.
