D1.C11.Wine Components Flashcards
What is the approximate percentage of water in wine?
85 %
The percentage of alcohol in wine depends on which factors?
- Alcohol by volume
- Level of residual sugar
- Other factors
What is the predominant alcohol in wine?
Ethanol
How does ethanol affect the taste of wine?
- Sweetness
- Bitterness
- Oral warmth
- Fullness in body
- Mouthfeel
What are the effects of alcohol levels of 14.5% and above on the taste of wine?
- Decrease in the volatility of the wine aromas
- Increase in bitterness
How can the balance be achieved in wines with high alcohol levels?
Sufficient fruit concentration
What are the sources of acids in wine?
- Acids coming from the grape itself: Tartaric acid and malic acid
- Acids produced in fermentation or malolactic conversion: Acetic acid, lactic acid
That is the proportion of malic and tartaric acid to the total acidity?
2/3
What happens when acetic acid reacts with alcohol in wine?
It becomes ethyl acetate (nail polish remover)
What are the effects of acidity in wine?
- It makes wine refreshing
- It makes the wine leaner on the palate
- Excessive acid makes the wine taste tart
- Lack of acidity makes the wine flabby
Which factor can alter the perception of acidity?
Residual sugar
What is the reason of firm acidity in cool climate Chardonnays
High levels of malic acid where malolactic conversion has been blocked
Why is total acidity and pH linked but not exactly correlated?
Due to the buffering effect of other molecules (e.g. potassium)
How is acidity measured and expressed most commonly?
- Most common measure is total acidity
- Usually expressed as the equivalent of grams per liter (gr/L) in tartaric acid
What is the typical range of total acidity in wine?
5.5-8.5 gr/L
How may the total acidity be expressed in France?
As sulfuric acid (the ratio between sulfuric acid and tartaric acid is 1:1.5)
What is the typical range of pH in wines?
3-4
What are the advantages of low pH in a wine?
- Increased microbiological stability
- Increased effectiveness of SO2
- Gives red wines a bright red colour
- Enhances the ability of the wine to age well
What are the sources of aromas in wine?
- Aromas from the grapes
- Aromas created by fermentation due to the presence of aroma precursors in grape must
- Aromas originating from fermentation and its by-products
- Aromas from other sources
What are the aromas that are found in grapes?
- Methoxypyrazines: Sauvignon Blanc; grassy, green pepper aroma
- Rotundone: Syrah, Grüner Veltliner; Pepper aroma
What are the aromas created by fermentation due to the presence of aroma precursors in grape must?
- Thiols: Example, 4MMP which gives the box tree aromas in Sauvignon Blanc
- Terpenes: Widely found in wines and giving fruity and floral aromas. Examples such as linalool and geraniol contribute to the grapey aromas/flavours in Muscat
What are the aromas originating from fermentation and its by-products?
- Esters:
+ Formed by the reaction of certain acids and alcohols
+ Responsible for many fresh and fruity aromas
+ The most ester is isoamyl acetate which gives aromas of banana when its concentration is high (for example in Beaujolais Nouveau)
+ Another common ester is ethyl acetate - Acetaldehyde:
+ Created due to oxidation of alcohol
+ It masks fresh fruit aromas and has a stale smell that is regarded as a fault in most wines
+ It is the distinctive smell of Fino sherry - Diacetyl:
+ It is created especially by malolactic conversion
+ Contributes a buttery aroma - Reductive sulphur compounds: Aromas can range from struck match, which may be desirable, to rotten eggs, which would be regarded as a fault.
What are the wine aromas from other sources
- Vanillin: Derived by ageing wine in new oak barrels
- Eucalyptol: Can be volatized from eucalyptus trees by heat and absorbed in the waxy layer of the skins of grapes in nearby vines
What is the usual amount of residual sugar in dry wines?
2-3 gr/L
What does residual sugar give to the wine in addition to sweetness?
Body
Describe the EU classification of sweetness levels in still wines
- Dry/sec/trocken: Up to 4 g/L RS, or not exceeding 9 g/L provided that total acidity expressed as grams of tartaric acid per litre is not more than 2 g below RS content
- Medium dry/demi-sec/halbtrocken: 4 g/L - 12 g/L RS, or up to 18 g/L provided that the total acidity expressed as grams of tartaric acid per litre is not more than 10 g below the RS content
- Medium or medium sweet/moelleux/lieblich: 12 g/L - 45g/L
- Sweet/doux/süss: > 45 g/L
What is the third most abundant part of a dry wine after water and alcohol?
Glycerol
What kinds of wines have higher levels of glycerol?
- Botrytis wines like Tokaji
- Wines made with carbonic maceration like Beaujolais
How does glycerol contribute to the taste of the wine?
- Smoother texture
- Perception of fullness
- Slightly sweet taste
Phenolics are made up of which compounds in wine?
- Anthrocyanins
- Tannins
How can the perception of tannins be influenced by other compounds in wine?
- Residual sugar make tannins seem softer
- High acidity make tannins appear more astirngent
