Wine Components

Question 1

What are the main components of wine?

Answer 1

1. water
2. alcohol
3. acids
4. wine aromatics
5. other flavors and aromas
6. residual sugar
7. glycerol
8. phenolics

Question 2

Approximately, what percentage of wine is water?

Answer 2

85%

Question 3

What is the predominant type of alcohol in wine?

Answer 3

Ethanol

Question 4

What does ethanol contribute to wine?

Answer 4

A sense of sweetness, bitterness, and oral warmth. Also contributes fullness of body and mouthfeel.

Question 5

What effect do alcohol levels of 14.5% and above have on the wine?

Answer 5

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.

Question 6

What are the principle acids in grapes?

Answer 6

• tartaric acid
• malic acid

Question 7

What types of acids can be formed during the winemaking processes?

Answer 7

• lactic acid
• acetic acid

Question 8

Which fault does acetic acid contribute to?

Answer 8

• volatile acidity

Question 9

What does acidity contribute to a wine?

Answer 9

It makes a wine more refreshing and will balance sugar and fruit concentration.

It will also make a wine seem lighter in body.

Question 10

What does malic acid specifically contribute to a wine?

Answer 10

• malic acid provides a firm acidity

Question 11

What is the most common measure of acidity?

Answer 11

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.

Question 12

What is the typical range of Total Acidity in wines?

Answer 12

5.5-8.5 g/L

Question 13

What positive effect does a low pH have on a wine?

Answer 13

• increases microbiological stability
• increases the effectiveness of SO2
• gives red wines a bright red color
• enhances a wine’s ability to age well

Question 14

What are the four sources of aromatics in wine?

Answer 14

• 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

Question 15

What are the two given examples of aromas from grapes that are given in the text?

Answer 15

• methoxypyrazines
• rotundone

Question 16

What are the two examples of aromas created by fermentation that are given in the text?

Answer 16

• thiols (e.g. 4MMP)
• terpenes

Question 17

What kinds of aromas do thiols give, and what is a good example of grape variety high in these compounds?

Answer 17

• Sauv Blanc is high in thiols (typical aromas are boxtree, passionfruit, and grapefruit)

Question 18

What aromas do terpenes give, and which grape variety is particularly high in these?

Answer 18

• fruity and floral aromas, Muscat

Question 19

Which type of aroma molecules are formed in a reaction between acids and alcohols during fermentation?

Answer 19

Esters are formed during fermentation through the action of yeasts.

Question 20

What kinds of aromas are esters responsible for?

Answer 20

• many fresh and fruit aromas in young wines, especially white wines

Question 21

Which molecule is produced by the oxidation of ethanol, and which type of wine is this compound desirable?

Answer 21

• 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

Question 22

Which compounds, often produced during MLC, give a buttery aroma?

Answer 22

• diacetyl

Question 23

Which two flavor molecules coming from other courses are listed in the text?

Answer 23

• vanillin: just one of the molecules coming from oak barrels
• eucalyptol, coming from the leaves of eucalyptus trees

Question 24

What does glycerol contribute to wine?

Answer 24

• contributes smoothness to the texture of wine, and a fuller body
• has a slightly sweet taste

Question 25

Where are phenolics formed in grapes?

Answer 25

- skins, seeds, and stems

Question 26

What are the two most important groups of phenolics for winemaking?

Answer 26

- anthocyanins (color) - tannins