Wine Components Flashcards
What are the main components of wine?
- water
- alcohol
- acids
- wine aromatics
- other flavors and aromas
- residual sugar
- glycerol
- phenolics
Approximately, what percentage of wine is water?
85%
What is the predominant type of alcohol in wine?
Ethanol
What does ethanol contribute to wine?
A sense of sweetness, bitterness, and oral warmth. Also contributes fullness of body and mouthfeel.
What effect do alcohol levels of 14.5% and above have on the wine?
They reduce volatility of wine aromas, and increase the sense of bitterness.
A wine with these levels needs sufficient fruit concentration to be in balance with the alcohol.
What are the principle acids in grapes?
- tartaric acid
- malic acid
What types of acids can be formed during the winemaking processes?
- lactic acid
- acetic acid
Which fault does acetic acid contribute to?
- volatile acidity
What does acidity contribute to a wine?
It makes a wine more refreshing and will balance sugar and fruit concentration.
It will also make a wine seem lighter in body.
What does malic acid specifically contribute to a wine?
- malic acid provides a firm acidity
What is the most common measure of acidity?
Total acidity, which is usually expressed as the equivalent in g/L of tartaric acid.
In France, this may be expressed as the equivalent of sulfuric acid.
What is the typical range of Total Acidity in wines?
5.5-8.5 g/L
What positive effect does a low pH have on a wine?
- increases microbiological stability
- increases the effectiveness of SO2
- gives red wines a bright red color
- enhances a wine’s ability to age well
What are the four sources of aromatics in wine?
- aromas from grapes
- aromas created by fermentation due to the presence of precursors in the grape must
- aromas originating from fermentation and its by-products
- aromas from other sources
What are the two given examples of aromas from grapes that are given in the text?
- methoxypyrazines
- rotundone
What are the two examples of aromas created by fermentation that are given in the text?
- thiols (e.g. 4MMP)
- terpenes
What kinds of aromas do thiols give, and what is a good example of grape variety high in these compounds?
- Sauv Blanc is high in thiols (typical aromas are boxtree, passionfruit, and grapefruit)
What aromas do terpenes give, and which grape variety is particularly high in these?
- fruity and floral aromas, Muscat
Which type of aroma molecules are formed in a reaction between acids and alcohols during fermentation?
Esters are formed during fermentation through the action of yeasts.
What kinds of aromas are esters responsible for?
- many fresh and fruit aromas in young wines, especially white wines
Which molecule is produced by the oxidation of ethanol, and which type of wine is this compound desirable?
- acetaldehyde is due to the oxidation of ethanol
- it usually masks fresh fruit aromas in wines, and is considered a fault
- distinctive character in Sherry
Which compounds, often produced during MLC, give a buttery aroma?
- diacetyl
Which two flavor molecules coming from other courses are listed in the text?
- vanillin: just one of the molecules coming from oak barrels
- eucalyptol, coming from the leaves of eucalyptus trees
What does glycerol contribute to wine?
- contributes smoothness to the texture of wine, and a fuller body
- has a slightly sweet taste
Where are phenolics formed in grapes?
- skins, seeds, and stems
What are the two most important groups of phenolics for winemaking?
- anthocyanins (color)
- tannins
