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certified specialist of wine (csw) - 2024 > 1. Wine Composition And Chemistry > Flashcards

1. Wine Composition And Chemistry Flashcards

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1
Q

What are the five main components of wine (in order)?

A

Water
Alcohol
Acid
Sugar
Phenolic Compounds

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2
Q

What percentage of wine is water? (Approximately)

A

Wine is typically 80-90% water.

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3
Q

What percentage of a wine is typically made up of alcohol?

A

Alcohol is typically 10-15% of the wine.

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4
Q

What is the main type of alcohol found in wine?

A

Ethanol or Ethyl Alcohol

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5
Q

How is Ethanol formed?

A

It is a product of fermentation.

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6
Q

What is the basic relationship between the “body” of a wine and the level of alcohol in the wine?

A

Typically, the higher the % of alcohol, the more full the body of the wine.

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7
Q

What percentage of a wine is typically comprised of Acids?

A

Typically 0.5% to 0.75% of the wine is made up by acids.

Tartaric acid is the most prevalent of acids in wine.

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8
Q

How is tartaric acid different from malic acid or citric acid?

A

1) There is more tartaric acid in a wine than malic or citric acid
2) Tartaric acid is higher in pH than malic or citric acid.

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9
Q

In what type of climate are you more likely to have grapes with high malic acid?

A

Cooler climates.

The level of malic acid decreases during the ripening process.

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10
Q

Wines from grapes grown in warmer climates tend to have ______ malic acid than those grown in cooler climates.

A

Less malic acid

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11
Q

Which is more prevalent in grapes, citric acid or tartaric acid?

A

Tartaric acid

Citric acid exists only in minute qualities. It is undetectable without specialized equipment.

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12
Q

Which type of acid is more acidic? Malic acid or lactic acid?

A

Malic acid

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13
Q

Which four types of acids are found in grapes?

A

Found in grapes:
Tartaric, Malic, Citric, Succinic

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14
Q

What does TA measure?

A

The total acidity of the wine (acids by volume).

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15
Q

What does pH measure?

A

The combined chemical strength of the acids.

The lower the pH, the stronger the acid level.

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16
Q

What is the typical pH of a wine?

A

2.9 - 3.9

The lower the pH, the more acidic the wine.

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17
Q

What percentage of ripe grapes is made up by sugar?

A

Grapes typically contain 15-28% sugar at harvest.

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18
Q

What are the two types of sugars found in grapes?

A

Glucose and Fructose, which are monosaccharides

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19
Q

Which type of sugar is more prevalent in ripe grapes? Glucose or fructose?

A

Glucose and fructose are present in roughly similar quantities in harvest ready grapes.

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20
Q

What it the relative relationship to the amount of sugar in a finished wine and its perceived body?

A

The higher the sugar level, the more full the body of the wine.

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21
Q

Is Succinic acid found in grapes or created during fermentation?

A

Both.

Its a minor component of grapes and a small amount is created during fermentation.

It can have a slightly bitter, sharp, salty flavor.

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22
Q

What are three alternate terms for Phenolic Compounds?

A

Phenolic
Polyphenolics
Polyphenols

23
Q

Name five examples of phenolic compounds in wine.

A

Anthocynanins
Flavonoids
Tannins
Vanillins
Resveratrol

24
Q

How are Anthocyanins different from Flavonols?

A

Anthocyanins are the phenolic compounds the give red wine its color.

Flavonols are the phenolic compounds that give white wine its yellow color. Flavonols are also referred to as Flavones.

25
Q

What gives red wine its color?

A

The color of red wine is influenced by both the amount of Anthocyanins and the amount of acid in the wine.

More acidic wines appear more red.
Less acidic wines appear more blue.

26
Q

Why do wines made from grapes from warmer climates appear more golden in color than wines made from grapes from cooler climates?

A

Flavonols (yellow pigments found in white wines) increase with exposure to sunlight.

Grapes with higher sunlight exposure have more Flavonols than grapes with less sunlight exposure.

27
Q

Where do tannins come from?

A

Primary: The stem, seeds, and skins of grapes.

Secondary: Through fermentation or aging in oak.

28
Q

Where does vanillin come from?

A

Vanillin comes primary from oak / oak aging.

29
Q

How does the level of toast of an oak barrel impact the level of vanillin in a wine?

A

The lighter the toast, the higher the transfer of vanillin.

30
Q

Which type of oak imparts more vanillin in wine? French, American, or Hungarian?

A

American

31
Q

Where are the phenolic compounds of a grape concentrated?

A

Primarily in the skin and seeds.

32
Q

Why are red wines richer in phenolics than white wines?

A

Red wines are richer in phenolics than white wines because phenolics are concentrated in the skin, stems, and seeds of a grape.

White grapes do not have significant (if any) contact with the skin, stem, and seeds during the wine making process.

Red wine has significantly more contact with the skin, stem, and seeds during the wine making process.

33
Q

What is the relationship to phenolic compounds and sediment in an aged red wine?

A

Over time, phenolic compounds in wine begin to combine into longer molecule chains (aka polymerize), some of which may become too heavy to remain suspended in the liquid. This drops out of the liquid and falls as sediment.

As this happens, red wines will typically become lighter in color and less acidic.

34
Q

What are Aldehydes?

A

Aldehydes are oxidized alcohols which form when wine is exposed to air.

35
Q

When are aldehydes intentionally formed?

A

With wines such as sherry and Madeira.

36
Q

What is acetaldehyde?

A

Acetaldehyde is the most common aldehyde in wine. It is formed by the oxidation of ethanol (when the wine is exposed to excessive levels of oxygen).

37
Q

What are esters?

A

Esters are molecules that result from the joining of an acid and an alcohol.

They are significant contributors to the aroma of the wine.

38
Q

What chemical component contributes most to a wine’s aroma?

A

Esters represent the largest group of odiferous compounds in a wine. Esters are created from the joining of acid and alcohol.

39
Q

What is ethyl acetate and what are its aromas?

A

Ethyl Acetate is the the ester of acetic acid and ethanol.

At low concentrations, this produces fruity and flowery aromas.

At higher concentrations,this produces aromas similar to that of nail polish, varnish, or glue.

40
Q

Why is sulfur used in wine?

A

Sulfur is a preservative that helps to protect wine from oxidation.

It is an antioxidant and an antibacterial agent.

All wine contains some level of sulfites given that sulfites are a natural byproduct of fermentation.

41
Q

At what level (parts per million) must a wine label indicate the presence of sulfites on the label in the US?

A

A wine that contains more than 10 parts per million (10ppm) of sulfur dioxide must list “contains sulfites” on the label.

42
Q

Compare Sulfite PPM of red wine, white wine, and dried fruit.

A

Red Wine: 50-350 ppm
White Wine: 250-450 ppm
Dried Fruit: 1000-3000 ppm

43
Q

Why might a wine have an aroma of nail polish?

A

Wine with higher concentrations of ethyl acetate (the ester of acetic acid and ethanol) may have aromas of nail polish, varnish, or glue.

44
Q

Where do a wine’s aromas come from?

A

The aromas of a wine may come from the grapes themselves, fermentation methods, use of oak, aging process, and level of oxidation.

45
Q

Which acids are created during fermentation?

A

Created during fermentation:
Lactic, Acetic, Succinic

46
Q

What other alcohols are found in wine in small quantities?

A

Methyl alcohol (methanol)

Glycerol

Fusel alcohols

47
Q

What is resveratrol?

A

A compound believed to have beneficial health affects in humans

48
Q

Describe malolactic conversion

A

Lactic acid bacteria converts Malic acid into lactic acid and diacetyl

49
Q

What is diacetyl

A

A byproduct of MLF with a powerful butter or butterscotch aroma

50
Q

How much residual sugar can be left in a wine?

A

0.8% - 24%

51
Q

What is the chemical composition of ethanol

A

C2H6O

52
Q

What is the role of carbon dioxide in wine?

A

To give sparkling wine bubbles

To promote the release of aromatic compounds in all wines

53
Q

How does sulfur prevent oxidation?

A

Sulfur absorbs free oxygen molecules before they affect the wine

54
Q

Is carbon dioxide present in still wines?

A

Yes, in small quantities. Some wine makers may allow enough to remain to create petillance in the wine

certified specialist of wine (csw) - 2024 (26 decks)

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