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CSW > Wine Composition and Chemistry > Flashcards

Wine Composition and Chemistry Flashcards

1
Q

Name 5 major components of wine

A 
Water
Alcohol
Acid
Sugar
Phenolic Compounds
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2
Q

Wine typically contains _____% of water.

A

80-90%

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3
Q

Wine typically contains _____% of alcohol by volume.

A

10-15%

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4
Q

What is ethyl alcohol?

A

the primary result of alcoholic fermentation and the main alcohol component of wine.
also known as ethanol

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5
Q

Name 4 other types of alcohol that can occur in wine production in small amounts.

A

Glycerol
Methyl Alcohol (Methanol)
Fusel Alcohols (Fusel Oils)
Higher Alcohols

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6
Q

Acid accounts for what percentage of a wine’s volume?

A

usually between 0.5% and 0.75%

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7
Q

What are the 6 principle acids in wine?

A 
Tartaric
Malic
Citric
Lactic
Acetic
Succinic
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8
Q

What is the most prevalent of the acids found in both grapes and wine?

A

Tartaric Acid

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9
Q

What are tartrates?

A

“Wine diamonds”-solid crystals formed by tartaric acid at low temperatures.

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10
Q

What winemaking process minimizes or avoids the formation of tartrates?

A

Cold Stabilization

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11
Q

True or False: Tartaric acid is the strongest of the acids found in wine in terms of pH.

A

True

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12
Q

What acid can be described as sharp-tasting and is frequently associated with green apples.

A

Malic Acid.

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13
Q

What acid is sometimes added to increase the total acidity in a wine?

A

Citric Acid-although its distinctive citrus fruit flavor makes it generally unsuitable for quality wines.

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14
Q

What are the 3 fermentation?

A

Lactic Acid
Acetic Acid
Succinic Acid

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15
Q

What causes the creation of lactic acid in wine?

A

lactic acid bacteria which convert malic acid into lactic acid through malolactic fermentation

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16
Q

Which of the wine acids are considered to be volatile?

A

Acetic Acid- most commonly found in vinegar, it readily evaporates and joins the aromas of the wine

17
Q

What is acetobacter?

A

a bacteria that when acetic acid is in higher concentration can cause a chemical reaction between ethanol and oxygen that makes a wine undrinkable.

18
Q

Describe Succinic Acid.

A
  • a minor component in grapes and a by-product of normal alcoholic fermentation.
  • has a sharp, slightly bitter, slightly salty flavor
19
Q

What are 2 numbers used to describe the acidity level of a wine and why are 2 different measurements used?

A

Total acidity (TA)
pH
-TA includes several acids, some of which are stronger than others

20
Q

What does pH measure?

A

The combined chemical strength of the acids present.

21
Q

Where is wine usually measured on the logarithmic pH scale?

A

between 2.9 and 3.9

- a lower pH indicates a stronger acid content

22
Q

Why do winemakers generally place particular emphasis on pH?

A

Because it gives an indication of stability and plays a role in determining sulfur additions

23
Q

What are the 2 sugars present in grapes?

A

Glucose

Fructose

24
Q

Name 5 phenolic compounds compounds.

A 
Anthocyanins
Flavonols
Tannins
Vanillin
Resveratrol
25
Q

What phenolic compound is responsible for giving red wine its color?

A

Anthocyanins

26
Q

How does the acidity of a red wine affect its color?

A

more acidic wines appear redder in hue, while less acidic ones appear blue

27
Q

What are Flavonols (flavones)?

A

Yellow pigments found in white wines.

28
Q

What causes the increase in Flavonols in grapes?

A

increased exposure to sunlight

-white wines from sunnier climates tend to have a more golden color than wines from cooler or cloudier climates

29
Q

What phenolic compound acts as a natural preservative and helps protect red wines from oxidation during the aging process?

A

Tannins

30
Q

Name an aromatic phenolic compound.

A

Vanillin

-found in oak barrels imparts a vanilla scent to barrel-aged wines.

31
Q

True or False:

The Vanillin found in oak barrels is the same compound found in vanilla beans.

A

True

32
Q

Which phenolic compound in wine is believed to have several beneficial health effects in humans?

A

Resveratrol

33
Q

What causes the formation of sediment in wines?

A

Over time, some phenolic compounds, particularly tannins and pigments, tend to polymerize, or combine into longer molecule chains and become too heavy to stay suspended in the liquid.

34
Q

What are Aldehydes?

A

oxidized alcohols that are formed when a wine is exposed to air.

35
Q

Name 2 types of wines that are made using special techniques that encourage the formation of aldehydes.

A

Sherry and Madeira

36
Q

What is the most common aldehyde found in wine and how is it created?

A

Acetaldehyde-formed by the oxidation of ethanol

CSW (3 decks)

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