Wine Composition: Understanding the Elements of Taste and Aroma
Wine Composition
Sweetness in Wine
The sweet taste in wine comes from various sugars and alcohols. Here are the key contributors:
Sugars
- Glucose: Found in grapes at around 15%, it contributes to the initial sweetness.
- Fructose: Present in grapes at approximately 25%, a small amount remains even after fermentation.
- Other sugars: Arabinose and xylose are also found in grapes and do not ferment.
Polyols
These include inositol, mannitol, arabitol, erythritol, and sorbitol, which contribute to the overall sweetness.
Alcohols
- Ethanol: The primary alcohol in wine (72-120 g/l), responsible for the aroma and warmth.
- Glycerol: Contributes to sweetness and body, formed during fermentation and in botrytized grapes.
- Butylene glycol: Adds a slightly sweet and bitter taste.
Acidity in Wine
Organic acids play a crucial role in wine’s acidity and balance. They can be free or bound to minerals like calcium, potassium, magnesium, and sodium.
Acids from Grapes
- Tartaric acid: The primary acid in grapes, contributing significantly to pH and overall acidity.
- Malic acid: Imparts an apple-like flavor and decreases during ripening and malolactic fermentation.
- Citric acid: Present in small amounts and diminishes during fermentation.
Acids Formed During Fermentation
- Succinic acid: Contributes to the overall taste of wine.
- Lactic acid: Produced from malic acid during malolactic fermentation, softening the acidity.
- Acetic acid: Responsible for the vinegar-like smell and taste when present in excess.
Salty Taste
Salts of sulfate, phosphate, chloride, malate, and lactate contribute to the refreshing, salty taste in wine.
Bitterness and Astringency
These sensations come from phenolic compounds found in grape skins, seeds, and stems, primarily in red wines.
Non-Flavonoids
- Phenolic acids: Found in skins, seeds, and stems, with bactericidal properties.
- Stilbenes: Such as resveratrol, contribute to the complexity of red wines.
Flavonoids
- Anthocyanins: Red pigments responsible for the color of red wines.
- Flavonols: Yellow pigments found in both white and red grapes.
- Tannins: Contribute to astringency and the aging potential of red wines.
Other Components
- Nitrogen compounds: Essential for yeast and bacteria growth.
- Pectin: Contributes to the texture and mouthfeel of wine.
- Gums: Act as protective colloids, similar to pectin.
- Mucilage: Found in botrytized grapes and can affect clarification.
- Volatile compounds: Responsible for the diverse aromas of wine, including acids, alcohols, aldehydes, ketones, and esters.
- Vitamins: Present in small amounts but crucial for yeast and bacteria growth.
Understanding the various components of wine allows for a deeper appreciation of its complexity and the factors influencing its taste and aroma.