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TBobbs CSW Flashcards > Wine Composition & Chemistry > Flashcards

Wine Composition & Chemistry Flashcards

1
Q

T/F Acetic acid is volatile.

A

true

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2
Q

What is another name for remaining sugar in a wine?

A

residual sugar

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3
Q

What is the primary result of alcoholic fermentation?

A

ethanol

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4
Q

Define acetobacter.

A

harmful bacteria that causes a chemical reaction between ethanol & oxygen that cause a high level of acetic acid that makes wine unpleasant & undrinkable

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5
Q

What aromas is associated with high levels of ethyl acetate?

A

nail polish remover, varnish, glue

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6
Q

What are the five major components of wine?

A
  1. water
  2. alcohol
  3. acid
  4. sugar
  5. phenolic compounds
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7
Q

Where does the water in wine primarily come from?

A

the grapes themselves

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8
Q

What four acids are grape acids?

A
  1. tartaric acid
  2. malic acid
  3. citric acid
  4. succinic acid
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9
Q

What is the combined chemical strength of the acids present in a wine?

A

pH level

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10
Q

Which acid is sharp-tasting and frequently associated with green apples?

A

malic acid

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11
Q

What is the most common aldehyde in wine?

A

acetaldehyde

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12
Q

What is the largest group of odiferous compounds found in wine?

A

esters

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13
Q

What are a large category of various molecules that are present in many wines that can have a major impact on the sensory profile of wine despite the quantity of these molecules?

A

phenolic compounds

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14
Q

What is slight bubbling under the surface called?

A

petillance

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15
Q

When phenolics polymerize they may cause what in a wine?

A

sediment

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16
Q

What are four types of alcohol in wine?

A
  1. ethyl (ethanol)
  2. glycerol
  3. methyl (methanol)
  4. fusel oils (higher alcohols)
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17
Q

How is acetaldehyde formed?

A

oxidation of ethanol

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18
Q

What two sugars are contained in grapes?

A
  1. glucose

2. fructose

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19
Q

What can be done during the winemaking process to minimize malic acid?

A

malolactic fermentation

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20
Q

What is often added to wine to absorb oxygen to prevent harm to the wine?

A

sulfur

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21
Q

How is lactic acide created in wine?

A

lactic acid bacteria converts malic acid

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22
Q

In the United States, wine must display a warning label if it contains how much sulfur?

A

10ppm (parts per million)

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23
Q

T/F Still wines contain no carbon dioxide.

A

false

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24
Q

T/F All wines contain tiny quantities of unfermentable sugars.

A

true

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25
Q

T/F Residual sugars contribute to the tears/legs in a wine glass.

A

true

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26
Q

What two wines are encouraged to form aldehydes?

A
  1. sherry

2. madeira

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27
Q

What are molecules that result from an acid and an alcohol joining?

A

esters

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28
Q

What phenolic compounds are astringent, bitter compounds that act as a preservative & help wines from oxidating?

A

tannins

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29
Q

What acid has a sharp, slightly bitter, slightly salty flavor?

A

succinic acid

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30
Q

What two numbers are used to describe the acidity level of a wine?

A
  1. Total acidity (TA)

2. pH level

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31
Q

What gas gives sparkling wine its bubbles

A

carbon dioxide (CO2)

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32
Q

T/F White wines from cooler or cloudier climates appear more golden than those from sunnier or warmer climates?

A

false

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33
Q

What is a volatile compound?

A

one that evaporates easily

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34
Q

What two acids are so minute in grapes that they are rarely measured?

A
  1. citric acid

2. succinic acid

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35
Q

What phenolic compound gives red wine its color?

A

anthocyanins

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36
Q

What is another name for “wine diamonds”?

A

tartrates

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37
Q

What is the phenolic compound that is aromatic and imparts a vanilla scent to barrel-aged wines?

A

vanillin

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38
Q

Why is malolactic fermentation used?

A

to soften and smooth the mouthfeel of wine

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39
Q

What does acid contribute to wine?

A

makes each wine unique; gives structure, balance, & refreshment

40
Q

What is another name for flavonols?

A

flavones

41
Q

What is the sugar composition of grapes at harvest?

A

15-28%

42
Q

T/F There are some wines that contain no sulfur

A

false

43
Q

How does carbon dioxide benefit wine?

A

keeps it feeling fresh & lively in the mouth & promotes the release of aromatic compounds

44
Q

Flavonols increase with what?

A

exposure to sunlight

45
Q

Name two by-products of malolactic fermentation.

A
  1. creamy texture

2. “buttery” aroma

46
Q

Define malolactic fermentation.

A

optional winemaking process in which lactic acid bacteria is used to convert malic acid into lactic acid

47
Q

Ethanol, as a volatile compound, does what for wine?

A

carries the wine’s aromas to the nose

48
Q

T/F The production of sediments causes wines to be less astringent.

A

true

49
Q

What is the approximate concentration of acid in wine?

A

0.5 - 0.75%

50
Q

What are three other names for phenolic compounds?

A
  1. phenolics
  2. polyphenolics
  3. polyphenols
51
Q

What can be recognized by the textural, drying sensation created in the mouth?

A

tannins

52
Q

What is an important preservative used to keep wines stable after fermentation?

A

sulfur

53
Q

Where are tannins found?

A

skins, seeds, stems, oak, oak barrels

54
Q

What is another name for ethyl alcohol?

A

ethanol

55
Q

What is another name for methyl alcohol?

A

methanol

56
Q

What can be done during the winemaking process to minimize the formation of tartrates?

A

cold stabilization

57
Q

Why would citric acid be added to wines?

A

to increase the total acidity of wine

58
Q

weight/body

A

tactile sensation of a wine as it rests on the palate

59
Q

T/F a lower pH indicates a lower acid wine

A

false

60
Q

T/F More acidic wines appear redder in hue, while less acidic ones appear blue.

A

true

61
Q

Ethyl acetate is formed from what?

A

acetic acid & ethanol

62
Q

Wines usually measure where on the pH scale?

A

between 2.9 and 3.9

63
Q

What is the approximate concentration of alcohol in wine?

A

10 - 15%

64
Q

What is the phenolic compound believe to have several health benefits to humans?

A

resveratrol

65
Q

What alcohol is the main component of wine?

A

ethanol

66
Q

T/F Citric acid is not usually found in grapes.

A

true

67
Q

Can tartaric acid redissolve into liquid after crystallization?

A

No

68
Q

What three acids are fermentation acids?

A
  1. lactic acid
  2. acetic acid
  3. succinic acid
69
Q

T/F White wines are higher in phenolics than red wine.

A

false

70
Q

What is another name for fusel alochol/oils?

A

higher alcohols

71
Q

When can wines become oxidized?

A

when open too long or exposed to heat

72
Q

What acid is strongest in terms of pH?

A

tartaric acid

73
Q

T/F Residual sugar does not contribute to the body of a wine.

A

false

74
Q

Does the body of a wine get heavier or lighter as alcohol increases?

A

heavier

75
Q

What is the volume of all the acids in a wine?

A

total acidity (TA)

76
Q

Describe the tears/legs of wine that has a high concentration of alcohol.

A

slow & thick

77
Q

T/F Acetic acid is always harmful to wine.

A

false

78
Q

T/F Tartrates are considered a defect in wine?

A

false

79
Q

What is one of the most common esters in wine?

A

ethyl acetate

80
Q

What are oxidized alcohols formed when wine is exposed to air?

A

aldehydes

81
Q

Name five common phenolic compounds.

A
  1. anthocyanins
  2. flavonols
  3. tannins
  4. vanillin
  5. resveratrol
82
Q

Where is acetic acid found usually?

A

most types of vinegar

83
Q

T/F Lactic acid is usually found in grapes.

A

false

84
Q

What gives fino sherries their distinctive aroma?

A

acetaldehyde

85
Q

What grapes are typically high in malic acid?

A

underripe and those from cool climates

86
Q

Define dry wine.

A

wines that have less sugar than a person can taste

87
Q

What does alcohol contribute to wine?

A

body/weight

88
Q

What aromas is associated with low levels of ethyl acetate?

A

fruity & floral

89
Q

What are the six principal acids in wine?

A
  1. tartaric acid
  2. malic acid
  3. citric acid
  4. lactic acid
  5. acetic acid
  6. succinic acid
90
Q

What is the most prevalent acid in both grapes & wine?

A

tartaric acid

91
Q

Where are phenolics of a grape found primarily?

A

skin and seeds

92
Q

Define polymerize.

A

when phenolic compounds combine into longer molecule chains over time

93
Q

What does tartaric acid form at low temperatures?

A

tartrates or “wine diamonds”

94
Q

What phenolic compound are yellow pigments found in white wines?

A

flavonols

95
Q

What phenolic compound forms part of the backbone of red wines?

A

tannins

96
Q

What is the approximate concentration of water in wine?

A

80 - 90%

TBobbs CSW Flashcards (4 decks)

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