Ch. 11 Wine Components

Question 1

What are the main components of wine and what do they contribute?

Answer 1

• Water - wine is approx 85% water - liquid form
• Alcohol - ethanol is predominant alc, contributes to fullness, oral warmth, sweetness, bitterness; 14.5% or above reduce volatility of aromas and increase sense of bitterness – need to be in balance w fruit concentration
• Acids - structure of wine, refreshing/lean character, should be in balance with RS and fruit concentration, tart vs flabby are 2 extremes
• Wine Aromatics
• Residual Sugars (RS)
• Glycerol
• Phenolics

Question 2

Which acids in wine come from grape and which come from fermentation processes?

Answer 2

Malic and Tartaric acid come from grape itself - make up about 66% of total acidity in wine

Lactic and acetic acid are produced in fermentation or malolactic conversion

Question 3

What is volatile acidity?

Answer 3

Mainly acetic acid (vinegar smell) - always present, but considered a fault in excess

acetic acid + ethanol = ethyl acetate (nail varnish remover smell)

Question 4

Explain why balanced acidity is important in a wine.

Answer 4

It affects the perception of other components in wine, for example RS.

Acidity and dryness are co-related when it comes to tasting, as they balance each other out. For ex, some German Rieslings taste dry even though they have high levels of RS because of high acidity.

Another example is structure and individual types of acids - high levels of malic acid will give wine firm acidity (style) - for ex cool climate Chard where malo has been blocked

Question 5

How are acidity and pH related?

Answer 5

A wine with high acidity would have low pH and vice versa

Question 6

How is acidity measured? What is typical range?

Answer 6

As total acidity - sum of all acids

g/L in tartaric acid

typically in range of 5.5 - 8.5 g/L

Question 7

What is pH? What is the range?

What effects do they have on winemaking?

Answer 7

A scale of measurement for the concentration of the EFFECTIVE acidity of a solution.

Range between 3-4. Inverse, so lower number means more concentrated acidity (wine will taste more acidic). Logarithmic scale, so 3 is 10x more acidic than 4

low pH (pH of 3 for ex) - high acid wines, usually white!

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

Question 8

What are the main sources for wine aromatics?

Answer 8

• Aromas from grapes
• aromas from precursors in grapes that are crreated by fermentation
• Aromas from process of fermentation and by products -
• Aromas from other sources

Question 9

Give examples of aromas from grapes

Answer 9

methoxypyrazines (green bell pepper, grassy),

rotundone (pepper i.e. Syrah, Guner)

Question 10

Give examples of aromas from precursors in grapes that are created by fermentation

Answer 10

• • thiols (4MMP - box tree in SB),

- terpenes (linalool, geraniol give fruity/floral/grapey aromas to Muscat)

Question 11

Give examples of Aromas from process of fermentation and by products

Answer 11

• esters - formed by yeasts during fermentation, involve reaction between acid + alc, isoamyl acetate gives fruity aromas like banana (Beaujolais Nouveau), plus apple and pineapple, important for young white wines!!l, ethyl acetate (can be fault), are volatile and will break down in a few months post-fermentation
• Acetaldehyde - oxidation of ethanol - important in Fino sherry but otherwise a fault because it masks fresh fruit aromas
• Diacetyl - malo, buttery aroma
• Reactive sulfur compounds during fermentation and lees ageing- struck match, rotten eggs

Question 12

Give examples of aromas in wine from other sources

Answer 12

• Vanillin - ageing wine in new oak barrels

- Eucalyptol -volatized from eucalyptus trees in heat, absorbed in waxy layer in nearby vines - Provence, Rhone

Question 13

How does Vincente Ferreira organize aromas in wine?

Answer 13

1. Compounds common to all wine - fermentation aromas - ehtanol, acetic etc
2. Impact aromas - can be recognized, like rotundone and 4MMP
3. Contributory aromas - mostly perceived when contributing/joined with other compounds in wines - vaniillin, ethyl acetate
4. Nonvolatile wine matrix- components of wine that affect how aromas are sensed

Question 14

What are the EU Classifications of Sweetness Levels?

Answer 14

• Dry/sec/trocken - up to 4 g/L RS. OR not exceeding 9 g/L as long as tartatic acid not more than 2 g below RS (i.e. 9 g/L RS can be trocken if total acidity is 7 g/L)
• Medium dry/demi-sec/halbtrocken - between 4-12 g/L, OR NOT exceeding 18 g/L provided TA is not more than 10 g below RS
• Medium or medium sweet/moelleux/lieblich - 12 g/l - 45 g/L
• Sweet/doux/suss - at least 45 g/L

Question 15

What is glycerol and what does it contribute to wine?

Answer 15

glycerol is derived from sugar in grapes - so occurs at higher levels in botrytis affected wines and carbonic maceration

Contributes smoothness, texture, perception of fullness of body

third most abundant part of wine after water and alcohol