11. Wine Components

Question 1

What does Volatile Acidity refer to?

When does it become a fault?

What aroma is associated with this fault?

Answer 1

Mainly refers to acetic acid, which reacts with alcohol = ethyl acetate.

Considered a fault when present in excess.

Vinegar (acetic acid) / Nail Polish Remover (ethyl acetate)

Question 2

How much of wine is water?

Answer 2

Approx. 85%, depending on abv / RS / other factors.

Question 3

What are the 4 components of Vinente Ferreira’s model for wine aromas?

Answer 3

1) compounds common to all wine (sweet, pungent aromas produced by fermentation -e.g. ethanol)
2) impact aromas (specific aromas that can be recognized – ex. rotundone (pepperiness) in Syrah)
3) contributory aromas (aroma compounds that are normally imperceptable but contribute when combined with other compounds – ex. vanillin from new oak)
4) nonvolatile wine matrix (nonvolatile components of wine that affect the way the aromatic compounds are sensed)

Question 4

What are the 7 main components of wine?

Answer 4

1) water
2) alcohol
3) acids
4) wine aromatics
5) residual sugar(s)
6) glycerol
7) phenolics

Question 5

What are the EU classifications for sweetness levels in still wine?

Answer 5

1) dry / sec / trocken = up to 4 g/l
2) medium-dry / demi-sec / halbtrocken = 4-12 g/l
3) medium / medium-sweet / moelleux / lieblich = 12-45 g/l
4) sweet / doux / süss = at least 45 g/l

Question 6

How is acidity most commonly measured / expressed and what is the normal range?

Answer 6

• in “total acidity” (sum of all acids) and expressed “g/l” in tartaric acidity
• normal range is 5.5-8.5 g/l

Question 7

What are methoxypyrazines?

Answer 7

Aroma compound found in e.g. Sauvignon Blanc, Cabernet Sauvignon, and give grassy, green bell pepper aroma

Question 8

What are the 4 main categories of aromas found in wine?

Give 1 example of each:

Answer 8

1) Aromas from grapes, e.g. Methoxypyrazines
2) Aroma-precursors present in must (aromas created by fermentation) e.g. Thiols
3) Aromas originating from fermentation + its by-products e.g. Diacetyl
4) Aromas from other sources e.g. Vanillin from oak

Question 9

What are terpenes?

Identify 2 specfic examples and describe how they manifest themselves:

Answer 9

An aromatic compound released during fermentation giving floral, “grapey” aromas

e.g. Linalool + Geraniol = grapey aromas in Muscat.

Question 10

What effect do tannins have on the palate?

What factors can influence the effect of tannins (3)?

How does tannin quality affect the quality of a wine?

Answer 10

• Tannins bind with proteins in saliva, producing the drying sensation on the palate.
• Perception of tannins can be influenced by other compounds in wine, e.g. RS can make them seem softer / high acidity can make them feel astringent.
• Tannins can react w/compounds during winemaking + maturation, changing their composition.
• Unripe tannins = bitter, undesirable.

Level/ripeness of tannins = key part of quality in red wines.

Question 11

What kind of scale is pH measured on and what is a typical range for wine?

What are some benefits of having a low pH (4)?

Answer 11

• measured on logarithmic, inverse scale
• 3-4 is typically the range
• increases microbial stability
• increases effectiveness of SO2
• gives red wines a bright colour
• enhances aging pontential

Question 12

What is glycerol?

Where does it come from (2)?

What does it contribute to the wine (3)?

Answer 12

• 3rd most abundant part of wine after water and alcohol
• derived from sugars in grapes, esp. Botrytis-affected + carbonic wines e.g. Tokaji, Beaujolais
• contributes smoothness to texture of wine, perception of fullness of body, slightly sweet taste.

Question 13

What are the 2 principal acids in wine and where do they come from?

What are 2 secondary acids in wine and where do they come from?

Answer 13

Tartaric and malic – both come from grape itself

Lactic and Acetic – produced in malolactic conversion or fermentation.

Question 14

What is acetaldehyde?

AKA

What is its effect and where is it commonly found?

Answer 14

• aroma occurring in wine due to oxidation of ethanol
• AKA “ethanal”
• masks fruit aromas and regarded as fault in most wines (nutty, briny aroma of Fino sherry)

Question 15

What are phenolics?

What are 2 specific examples?

Answer 15

Important group of compounds occuring in skins, stems and seeds of grapes.

• anthocyanins + tannins.

Question 16

Give 3 examples of typical wines that will have distinctly different levels of RS (and their sugar content in g/L):

Answer 16

Dry wine (e.g. Chablis) : ~2-3g/l

Sauternes: ~150g/l

PX Sherry: ~400g/l

Question 17

What is the link between total acidity and pH?

Why is this a link and not an exact correlation?

Answer 17

Linked but not correlated due to buffering effect of other mols. e.g. Potassium

– a wine with high acidity would normally have a low pH and vice versa.

Question 18

What are thiols?

Identify a specfic example and describe it:

Answer 18

Aromatic compounds released during fermentation (aroma precursors)

e.g. 4MMP = box tree aromas in Sauvignon Blanc

Question 19

What are 2 examples of aromas from sources other than the grapes and fermentation?

How do they manifest themselves in wine?

Answer 19

1) vanillin - gives aromas of vanilla, comes from aging wine in new oak
2) eucalyptol - abosorbed by waxy layer of skins from nearby eucalyptus trees

Question 20

How are acidity and perception of dryness related?

E.g. that illustrates this point:

Answer 20

• Perception of acidity + dryness is affected by level of acidity + balance btw/acidity and RS.
  e. g. some German Rieslings taste dry despite containing significant levels of RS (~9g/l) because the acidity is elevated.

Question 21

What are 2 examples of aroma compounds that originate in the grapes and what do they smell like?

Give 2 examples of varietals that contain these:

Answer 21

1) methoxypyrazines = grassy, green bell pepper; Sauvignon Blanc, Cabernet Sauvignon.
2) rotundone = black/white pepper; Syrah, Grüner Veltliner.

Question 22

What does acidity contribute to the structure of a wine (2)?

How does high/low acidity affect a wine’s profile (3)?

e.g. of how specific acidities affect the wine’s profile:

Answer 22

Acidity makes wine refreshing / balances out fruit concentration and (if present) RS.

• High acidity makes a wine seem “leaner” on the palate.
• Excessive acid creates tartness.
• Deficit of acid creates flabiness.
  e. g. higher levels of malic acid = firm acidity which contributes to style, e.g. cool climate Chardonnay where MLC has been blocked.

Question 23

What is the predominant type of alcohol in wine and when is it formed?

What does this contribute to the wine (3)?

Answer 23

Ethanol – formed during fermentation

• sense of sweetness / bitterness.
• oral warmth.
• fullness of body + mouthfeel.

Question 24

What is diacetyl?

How does it manifest itself in wine?

Answer 24

• aroma produced during MLF
• contributes buttery aromas common in rich styles of Chardonnay.

Question 25

What are esters?

What is the most common, what are its characteristics and where is it often found?

Answer 25

• aroma compounds formed through action of yeasts in the fermentation process (responsible for fresh and fruity aromas)
• the most common is isoamyl acetate (banana), commonly found in Beaujolais Nouveau.

Question 26

What are aroma precursors?

What are 2 examples?

Answer 26

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

(ex. thiols and terpenes)

Question 27

What is rotundone?

Answer 27

Aroma compound that produces a white/black pepper aroma in wines such as Gruner Veltliner and Syrah.

Question 28

How do high alcohol levels affect the flavor/aroma profile of a wine?

What must a winemaker do to ensure a high quality wine?

Answer 28

High abv (>14.5%) reduce volatility of wine aromas, increase sense of bitterness.

Winemakers must ensure wine has sufficient fruit concentration to be in balance w/alcohol.