Wine components

Question 1

Name the 7 wine components

Answer 1

• Water
• Alcohol
• Acids
• Wine aromatics
• Residual sugar (RS)
• Glycerol
• Phenolics

Question 2

Wine component: Water

Answer 2

Wine is approx 85% water by volume, depending on the abv, level of rs and other factors.

Water is critical for the way a wine flows as a liquid.

Question 3

Wine component: Alcohol

Answer 3

Ethanol, formed during fermentation, is the predominant alcohol in wine and has a slightly sweet smell

Alcohol contributes a sense of sweetness, bitterness and oral warmth and contributes to the fullness of the body of the wine and mouthfeel.

High alcohol levels, above 14.5%, reduce the volatility of wine aromas and increase the sense of bitterness and must have sufficient fruit concentration to be in balance with the alcohol.

Question 4

Wine component: Acids

Answer 4

Acidity contributes to the structure of the wine, makes wine refreshing and should be in balance with the fruit concentration and, if present, residual sugar (depends on the style of wine).

High acid –> lean
Excessive acid –> tart
Lack of acid –> flabby

Principal acids, tartaric and malic acid, come from the grape itself. Other acids like lactic and acetic acid are produced in fermentation.

Volatile acidity mainly refer to acetic acid (vinegar smell) generally present in all wine ins low concentrations, only a fault when in excess.

Acetic acid reacts with alcohol in the wine and becomes ethyl acetate (nail polish remover) all a fault when in excess.

Question 5

‘Total acidity’

Answer 5

Typically in the range of 5.5-8.5 g/l and is the sum of all the acids in the wine. Usually be expressed as the equivalent of grams per liter in tartaric acid.

A wine with high acidity would usually have a low pH, and vice versa. Wines typically have a pH in the range of 3-4. The lower the number the more concentrated the acidity (and sharper the wine will taste).

A low pH increases the microbiological stability of wine, increases the effectiveness of so2, gives red wines a bright red colour and enhance a wine’s ability to age well.

Question 6

Four sources of aromatics compounds

Answer 6

• Aromas from the grape
• Aromas created by fermentation due to the presence of aroma precursors in the grape must
• Aromas originating from fermentation and its by-products
• Aromas from other sources

Question 7

Aromas from the grape

Answer 7

Methoxypyrazines:
Occurs in the Sauvignon Blanc variety and give a grassy, green pepper aroma

Rotundone:
Occurs in Syrah and in Gruner Veltliner, producing a pepper aroma.

Question 8

Aromas created by fermentation due to the presence of aroma precursors in the grape must

Answer 8

Aroma precursors are compounds that are not in themselves aromatic but are building block which become aromatic during fermentation.

Thiols; are aromatic compounds released during fermentation. 4MMP –> box tree aromas in Sauvignon Blanc.

Terpenes; are aromatic compounds formed during fermentation. Widely found in wines, giving fruity and floral aromas. Linalool/geraniol –> grapey aromas in Muscat.

Question 9

Aromas originating from fermentation and its by-products

Answer 9

Some aromas are created from fermentation and it’s by-products, such as lees

Esters; Mainly created through the action of yeast in the fermentation process.
- Isoamyl acetate –> banana (Beaujolais Nouveau) and aroma’s like apple, pineapple

Acetaldehyde; occurs in wines due to the oxidation of ethanol, it masks fresh fruit aromas and has a stale smell (fault in most wines). It’s an important component of the distinctive smell of Fino sherry.

Diacetyl; produced during fermentation and especially malolactic conversion –> buttery aroma

In certain conditions, yeast can produce reductive sulfur compounds during fermentation and lees aging. Depending on their levels of concentration, aromas can range from struck match (desirable) to rotten eggs (fault)

Question 10

Aromas from other sources

Answer 10

Vanillin; aromas of vanilla, ageing wine in new oak barrels

Eucalyptol; can be volatilized from eucalyptus trees by heat and absorbed in the skas of grapes nearby vines

Question 11

Residual Sugar (RS)

Answer 11

In addition to contributing a level of sweetness to wines, residual sugar gives more body to the wine

Question 12

EU classification of sweetness levels (still wines)

Answer 12

Dry/sec/trocken:

• up to 4 g/l rs
• or a wine with 9 g/l rs can be labelled dry if its as 7 g/l total acidity

Medium dry/demi-sec/halbtrocken:

• 4 - 12 g/l rs
• or up to 18 g/l if the total acidity per litre is not more than 10 g below the rs content

Medium sweet/moelleux/lieblich:
- 12 - 45 g/l rs

Sweet/doux/suss:
- at least 45 g/l rs

Question 13

Glycerol

Answer 13

Derived from the sugar in grapes, occurs in higher levels in botrytis affected grapes (Tokaij) and wines made by carbonic maceration.

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

Question 14

Phenolics

Answer 14

Compounds that occur in the grape skins, stems and seeds. They include Anthocyanins (color pigments) and tannins. Tannins bind with proteins in the mouth, giving a drying sensation on the palate.

RS can make tannins seem softer

Dry wines with high acidity can make tannins appear more astringent

Unripe tannins generally taste bitter and are never desirable.

The level and nature present in the wine is considered a key part of quality red wines.