Chapter 11 Wine Components

Question 1

Define Ethanol

Answer 1

The predominant alcohol in wine: one of the main components of wine created during fermentation. It has a sweet smell.

Question 2

How does ethanol affect the wine?

Answer 2

Contributes:
* Sense of sweetness and bitterness
* Gives oral warmth
* Fullness of the body of the wine
* Mouthfeel
* Reduces volatility of aromas and increases sense of bitterness above 14,5%

Question 3

Define Volatile acidity

Answer 3

Mainly refers to the presence of acetic acid (vinegar smell) present in wines in low concentration and can be a fault when in excess.

Question 4

What acids can be present in the wine and where do they come from?

Answer 4

• Tartaric (grape)
• Malic (grape)
• Lactic (malolactic conversion)
• Acetic (fermentation)

Question 5

Define total acidity

Answer 5

The sum of all acids expressed in grams per liter (g/L) in tartaric acid. Total acidity is around 5.5-8.5 g/L for wines.

Question 6

What does acetic acid interacts with?

Answer 6

Acetic acid interacts with the alcohol in the wine and becomes ethyl acetate (Hal varnish remover smell). It can be a fault when in excess.

Question 7

Define pH

Answer 7

pH is a scale of measurement for the concentration of the acidity. Wines have a pH of 3-4.

Question 8

How does acidity affect the style of the wine?

Answer 8

• It contributes to the structure of the wine.
• Makes the wine refreshing.
• High acid makes a wine feel leaner on the palate.
• Too much acidity and the wine tastes tart.

Question 9

What does high acidity / low pH do to the wine?

Answer 9

• Increases the microbial stability.
• Increases the effectiveness of SO2.
• Gives red wines a bright red color.
• Enhances a wine’s ability to age well.

Question 10

Define Methoxypyrazines

Answer 10

One of the aromas that come from grapes. It gives aromas of grass and green pepper. Present in Sauvignon Blanc.

Question 11

Define Rotundone

Answer 11

One of the aromas that come from grapes. It gives aromas of pepper. Present in Syrah, Gruner Viltliner.

Question 12

Define Aroma Precursos

Answer 12

Compounds that are not aromatic but will become aromatic during fermentation.

Question 13

Define Thiols

Answer 13

A category of aromatic compounds that are released during fermentation. e.g. 4MMP that gives box tree aromas in Sauvignon Blanc.

Question 14

Define Terpenes

Answer 14

A category of aromatic compounds that are released during fermentation giving fruity and floral aromas. e.g. linalool and geraniol contribute to the grapey aromas of Muscat.

Question 15

Define Esters

Answer 15

An aromatic compound formed by the reaction of certain acids and alcohols. The majority are created through the action of yeast in the fermentation process.

Question 16

How does Esters affect the wine?

Answer 16

They are responsible for fresh and fruity aromas in wines. Important in white and young wines. Most esters are unstable and will break down a few months after fermentation.

Question 17

What is the most common type of Esther?

Answer 17

Isoamyl acetate which gives aromas of banana when in high concentration (e.g. Beaujolais nouveau)

Question 18

Define Acetaldehyde

Answer 18

An aromatic compound that occurs due to oxidation of ethanol (aka ethanal) Important in Fino Sherry but is a fault in most wines: mask fresh fruit aromas and has a stale smell.

Question 19

Define Diacetyl

Answer 19

An aromatic compound produced during fermentation and especially malolactic conversion. Contributes to a buttery aroma.

Question 20

Define Vanillin

Answer 20

Aroma compound that gives aromas of vanilla by aging wine in new oak barrels.

Question 21

Define Eucalyptol

Answer 21

Aroma compound which can be volatized from eucalyptus trees by heat and absorbed in the waxy layer of the skins of grapes. May be a defect in wines.

Question 22

Define Residual sugar

Answer 22

The amount of sugar in the wine. It contributes to the body as well as sweetness.
* Dry wines have 2-3 g/L
* Sauternes 150 g/L
* Pedro Ximenez 400 g/L

Question 23

Define Dry/sec/trocken

Answer 23

EU Law - up to 4 g/L RS
Up to 9 g/L if total acidity expresed as grams of tartaric acid per liter is not more than 2 g below RS content.

• < 4 g/L
• < 9g/L if tartaric acid < 7g/L

Question 24

Define medium dry / Demi-sec / halbtrocken

Answer 24

• 4 < Medium dry < 12 g/L
• < 18 g/L if tartric acid < 8 g/L

Question 25

Define Medium or medium sweet / moelleux / lieblich

Answer 25

12 g/L < Medium < 45 g/L

Question 26

Define sweet / roux / Suss

Answer 26

> 45 g/L

Question 27

Define glycerol

Answer 27

The third more abundant part of wine after wine and alcohol (in dry wines)

It is derived from the sugar in grapes. Occurs in Botryts affected grapes and wines made by carbonic maceration (less than botrytis).

Question 28

How does Glycerol affects wine?

Answer 28

Contributes smoothness to the texture of wine and the perception of the fullness of the body. It has slightly sweet taste.

Question 29

Define phenolics

Answer 29

Group of compounds that occur in grapes (skins, stems and seeds).

They include anthocyanins (responsible for the colour of red and rosé) and tannins.

Question 30

How does tannins affect the palate?

Answer 30

Tannins bind to proteins in the mouth giving a drying sensation in the palate.

Question 31

How does tannis are affected?

Answer 31

• RS in the wine make tannins softer.
• Dry wine with high acidity make tannins appear more astringent.

Question 32

How does tannins affect the wine?

Answer 32

Tannins react with others compounds in wine during winemaking and maturation. (see defining ripeness)

Unripe tannins have a bitter taste. So the level and nature of tannins and there role in the balance and structure of the wine is key for the quality of the wine.