11. Wine Components

Question 1

Where do the compounds that make up wine come from?

Answer 1

• Some come directly from the grapes
• Some are formed during the fermentation process
• Some are added during winemaking

Question 2

Approximately what percent water by volume is wine? What does this depend on?

Answer 2

85%

• abv
• level of residual sugar

Question 3

What are the 7 main compounds found in wine?

Answer 3

1. Water
2. Alcohol
3. Acids
4. Aromatic Compounds
5. Residual Sugar
6. Glycerol
7. Phenolics

Question 4

What is the predominant alcohol found in wine?

Answer 4

Ethanol

Question 5

When does ethanol in wine form?

Answer 5

During fermentation

Question 6

Describe what ethanol adds to a wine.

Answer 6

• slightly sweet smell
• sweetness
• bitterness
• oral warmth
• adds to body & mouthfeel

Question 7

What is a considered a high alcohol abv? What does high alcohol add to the wine? What is required to balance this high alcohol?

Answer 7

• > 14.5% abv
• contributes to body and mouthfeel
• increase the sense of bitterness ,
• reduces volatility of flavours
• requires sufficient fruit concentration to be in balance

Question 8

What are the 2 principal acids of wine? What are other 2 acids?

Answer 8

Principal:
- tartaric acid
- malic acid
Other:
- lactic acid
- acetic acid

Question 9

Where do tartaric and malic acid originate?

Answer 9

In the grapes

Question 10

Where do lactic and acetic acid originate?

Answer 10

Produced during fermentation or malolactic conversion

Question 11

In warm climates, what percentage of wine acid do tartaric and malic acid account for?

Answer 11

2/3 of the total acidity in wine

Question 12

What is volatile acidity? What does it smells like?

Answer 12

• present in all wines, generally in low concentrations, and is only a fault when in excess
• mainly refers to acetic acid
• vinegar smell

Question 13

What does volatile acidity smell like?

Answer 13

vinegar

Question 14

What is referred to by the term Volatile acidity and how does this evolve into a fault.

Answer 14

Volatile acidity generally refers to acetic acid

• reacts with alcohol to becomes ethyl acetate
• nail varnish remover smell
• ethyl acetate is fault when in excess

Question 15

What does acidity contribute to wine?

Answer 15

• contributes to structure
• makes wine refreshing
• should be in balance with fruit (and residual sugar when applicable)

Question 16

What happens when there is is too much acid? Too little acid?

Answer 16

• Too much: Tart

- Too little: Flabby

Question 17

What commonly comes into play when perceiving acidity? Give an example.

Answer 17

• Balance of acidity and residual sugar
• Example: some German Rieslings taste dry despite having significant levels of residual sugar (up to around 9 g/l) because of the elevated level of acidity.

Question 18

Give an example of a wine with high levels of malic acid and how those levels affect the style.

By contrast what is the effect of malic acid conversion

Answer 18

Cool climate Chardonnay where the malolactic conversion has been blocked
- Firm acidity profile

Malic acid conversion reduces the malic acid level in the wine (it is converted to lactic acid). The over all acid level decreases (softer), complexity in the wine increases with aromas of butter from the lactic acid.

Question 19

Are total acidity and pH correlated in wine? Why or why not?

Answer 19

• Linked, but not exactly correlated
• Buffering effect of other molecules (e.g. potassium).
• A wine with high acidity would usually have a low pH, and vice versa

Question 20

How is acidity most commonly measured?

Answer 20

• ‘total acidity’, the sum of all the acids
• grams per litre (g/l) in tartaric acid

In France
if expressed as Sulfuric Acid the convers is 1 : 1.15

Question 21

What is the typical range of total acidity in a wine?

Answer 21

• 5.5–8.5 g/l.

Question 22

How is acidity commonly measured in France?

Answer 22

• expressed as ‘sulfuric acid’

- the ratio between sulfuric acid and tartaric acid is 1:1.5

Question 23

What is pH?

Answer 23

• PH measures concentration of the effective acidity of a solution
• inverse scale: the lower the number the more concentrated the acidity
• logarithmic scale: a pH of 3 is ten times more acidic than a pH of 4

Question 24

What is the typical pH range of wines?

Answer 24

3-4

Question 25

What does a low pH mean for the wine? What does it mean for red wines?

Answer 25

- Increases the microbiological stability of wine - Increases the effectiveness of SO2 - enhances a wine’s ability to age well - Gives red wines a bright red colour

Question 26

What are the 4 sources of aromatic compounds?

Answer 26

1. Aromas from the grapes 2. Aromas created by fermentation due to the presence of aroma precursors in grape must 3. Aromas originating from fermentation and its by-products 4. Aromas from other sources

Question 27

Name 2 aromatic compounds found in grapes. What aromas does it give off? Give an example of a grape in which the compound is found.

Answer 27

1. Methoxypyrazines: grassy, green pepper aroma (Sauvignon Blanc) 2. Rotundone: pepper aroma (Syrah, Grüner Veltliner)

Question 28

What are aroma precursors?

Answer 28

Compounds that are not in themselves aromatic but are building blocks which become aromatic during fermentation

Question 29

Name 2 aroma precursors found in grapes. What aromas do they give off? Give an example of a each, and name a grape variety in which they are found.

Answer 29

1. Thiols - - Example: 4MMP, gives the box tree aromas (Sauvignon Blanc) 2. Terpenes: give fruity and floral aromas - - Examples: linalool, geraniol, contribute to the grapey aromas/flavours (Muscat)

Question 30

Name 4 aromas that originate during fermentation.

Answer 30

1. Esters 2. Acetaldehyde 3. Diacetyl 4. Reductive Sulfur

Question 31

What are esters? What types of aromas are they responsible for? In what types of wines are esters most important?

Answer 31

- Compounds formed by the reaction of certain acids and alcohols during fermentation - Most created through the action of yeasts - Most unstable; breakdown a few months after fermentation - Aromas: fresh and fruity (banana (isoamyl acetate), apple, pineapple, etc.) - essential in young wines, mostly white

Question 32

What is the most common ester? What aroma does it give off? Give an example.

Answer 32

- isoamyl acetate - banana (when its concentration is high) - Example: Beaujolais Nouveau

Question 33

Name another common ester.

Answer 33

- ethyl acetate

Question 34

What is acetaldehyde? What aromas does it give off? Give an example of a wine in which acetaldehyde is important.

Answer 34

- Occurs in wines due to the oxidation of ethanol. - AKA ethanal - masks fresh fruit aromas - stale smell - regarded as a fault in most wines - Distinguishing aroma for Fino sherry

Question 35

What is diacetyl? What aromas does it give off?

Answer 35

- Produced during fermentation, especially malolactic conversion - Buttery aroma

Question 36

Describe how reductive sulphur compounds might form and smell.

Answer 36

Form: - produced by yeast during fermentation and lees aging Smells: - struck match (could be desirable) - rotten eggs (fault)

Question 37

What is vanillin? What aromas does it give off?

Answer 37

- aromatic compounds derived by ageing wine in new oak barrels - vanilla

Question 38

What is eucalyptol and how can it get into wine?

Answer 38

- volatized from eucalyptus trees by heat | - absorbed in the waxy layer of the skins of grapes in nearby vines

Question 39

Describe Vincente Ferreira’s model for wine aromas.

Answer 39

There are 4 types of wine aromas: 1. Compounds common to all wines - aromas products by fermentation - e.g. ethanol, high alcohols, some acids (acetic) - slightly sweet, pungent, alcoholic, little fruity 2. Impact aromas - specific aromas that can be recognized - e.g. rotundone, 4MMP 3. Contributory aromas - aroma compounds that are below their normal individual perception threshold but make a contribution when they are with certain other compounds - e.g. ethyl acetate (fruity note at low levels) - e.g. vanillin (vanilla) 4. Nonvolatile Wine Matrix - the nonvolatile components of wine that affect the way the aromatic compounds are sensed

Question 40

How much residual sugar is found in dry wines?

Answer 40

small amount of RS (2–3 g/l)

Question 41

How much residual sugar is found in Sauternes? Pedro Ximenez sherry?

Answer 41

- Sauternes: 150 g/l | - Pedro Ximenez: 400 g/l

Question 42

In addition to sweetness, what does RS add to w ine?

Answer 42

body

Question 43

Does the sweetness level have to appear on labels in the EU?

Answer 43

No

Question 44

Give an example of a EU wine region that encourages using sweetness codes on labels.

Answer 44

Alsace

Question 45

What 2 factors does the EU classification for sweetness take into account?

Answer 45

1. levels of residual sugar 2. optionally higher levels of RS for wine with higher total acidity (goal is to guide consumers to the taste of the final wine)

Question 46

What are the 4 levels of sweetness classification in the EU? And their related levels

Answer 46

1. Dry/sec/trocken - Up to 4 g/l RS OR - not exceeding 9 g/l if total acidity is not more than 2 g below RS content 2. Medium dry/demi-sec/halbtrocken - 4 g/l - 12 g/l RS OR - up to 18 g/l provided that the total acidity is not more than 10 g below the RS content 3. Medium or medium sweet/moelleux/lieblich 12 g/l - 45 g/l RS. 4. Sweet/doux/süss >= 45 g/l RS

Question 47

What is glycerol? What does it add to the wine?

Answer 47

- derived from the sugar in grapes - adds - smoothness to the texture of wine - perception of the fullness of the body - slightly sweet taste

Question 48

In what types of wines does glycerol occur in higher levels?

Answer 48

- botrytis-affected grapes (e.g. Tokaji) | - carbonic maceration (Beaujolais) - lesser

Question 49

What are phenolics?

Answer 49

- Includes anthocyanins and tannins | - compounds that occurs in grapes, especially in the skins, stems and seeds

Question 50

What are anthocyanins?

Answer 50

Colour pigments responsible for the red colour – and sometimes blue tints – of red and rosé wines

Question 51

What are tannins?

Answer 51

- phenolic compound | - bind with proteins in the mouth, giving a drying sensation on the palate

Question 52

When are tannins perceived softer / more astringent?

Answer 52

- Softer: A little residual sugar | - More astringent: Dry wines with high acidity

Question 53

What do unripe tannins taste like?

Answer 53

- bitter | - never desirable