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Wine Composition & Chemistry Flashcards

(96 cards)

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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
T/F Residual sugars contribute to the tears/legs in a wine glass.
true
26
What two wines are encouraged to form aldehydes?
1. sherry | 2. madeira
27
What are molecules that result from an acid and an alcohol joining?
esters
28
What phenolic compounds are astringent, bitter compounds that act as a preservative & help wines from oxidating?
tannins
29
What acid has a sharp, slightly bitter, slightly salty flavor?
succinic acid
30
What two numbers are used to describe the acidity level of a wine?
1. Total acidity (TA) | 2. pH level
31
What gas gives sparkling wine its bubbles
carbon dioxide (CO2)
32
T/F White wines from cooler or cloudier climates appear more golden than those from sunnier or warmer climates?
false
33
What is a volatile compound?
one that evaporates easily
34
What two acids are so minute in grapes that they are rarely measured?
1. citric acid | 2. succinic acid
35
What phenolic compound gives red wine its color?
anthocyanins
36
What is another name for "wine diamonds"?
tartrates
37
What is the phenolic compound that is aromatic and imparts a vanilla scent to barrel-aged wines?
vanillin
38
Why is malolactic fermentation used?
to soften and smooth the mouthfeel of wine
39
What does acid contribute to wine?
makes each wine unique; gives structure, balance, & refreshment
40
What is another name for flavonols?
flavones
41
What is the sugar composition of grapes at harvest?
15-28%
42
T/F There are some wines that contain no sulfur
false
43
How does carbon dioxide benefit wine?
keeps it feeling fresh & lively in the mouth & promotes the release of aromatic compounds
44
Flavonols increase with what?
exposure to sunlight
45
Name two by-products of malolactic fermentation.
1. creamy texture | 2. "buttery" aroma
46
Define malolactic fermentation.
optional winemaking process in which lactic acid bacteria is used to convert malic acid into lactic acid
47
Ethanol, as a volatile compound, does what for wine?
carries the wine's aromas to the nose
48
T/F The production of sediments causes wines to be less astringent.
true
49
What is the approximate concentration of acid in wine?
0.5 - 0.75%
50
What are three other names for phenolic compounds?
1. phenolics 2. polyphenolics 3. polyphenols
51
What can be recognized by the textural, drying sensation created in the mouth?
tannins
52
What is an important preservative used to keep wines stable after fermentation?
sulfur
53
Where are tannins found?
skins, seeds, stems, oak, oak barrels
54
What is another name for ethyl alcohol?
ethanol
55
What is another name for methyl alcohol?
methanol
56
What can be done during the winemaking process to minimize the formation of tartrates?
cold stabilization
57
Why would citric acid be added to wines?
to increase the total acidity of wine
58
weight/body
tactile sensation of a wine as it rests on the palate
59
T/F a lower pH indicates a lower acid wine
false
60
T/F More acidic wines appear redder in hue, while less acidic ones appear blue.
true
61
Ethyl acetate is formed from what?
acetic acid & ethanol
62
Wines usually measure where on the pH scale?
between 2.9 and 3.9
63
What is the approximate concentration of alcohol in wine?
10 - 15%
64
What is the phenolic compound believe to have several health benefits to humans?
resveratrol
65
What alcohol is the main component of wine?
ethanol
66
T/F Citric acid is not usually found in grapes.
true
67
Can tartaric acid redissolve into liquid after crystallization?
No
68
What three acids are fermentation acids?
1. lactic acid 2. acetic acid 3. succinic acid
69
T/F White wines are higher in phenolics than red wine.
false
70
What is another name for fusel alochol/oils?
higher alcohols
71
When can wines become oxidized?
when open too long or exposed to heat
72
What acid is strongest in terms of pH?
tartaric acid
73
T/F Residual sugar does not contribute to the body of a wine.
false
74
Does the body of a wine get heavier or lighter as alcohol increases?
heavier
75
What is the volume of all the acids in a wine?
total acidity (TA)
76
Describe the tears/legs of wine that has a high concentration of alcohol.
slow & thick
77
T/F Acetic acid is always harmful to wine.
false
78
T/F Tartrates are considered a defect in wine?
false
79
What is one of the most common esters in wine?
ethyl acetate
80
What are oxidized alcohols formed when wine is exposed to air?
aldehydes
81
Name five common phenolic compounds.
1. anthocyanins 2. flavonols 3. tannins 4. vanillin 5. resveratrol
82
Where is acetic acid found usually?
most types of vinegar
83
T/F Lactic acid is usually found in grapes.
false
84
What gives fino sherries their distinctive aroma?
acetaldehyde
85
What grapes are typically high in malic acid?
underripe and those from cool climates
86
Define dry wine.
wines that have less sugar than a person can taste
87
What does alcohol contribute to wine?
body/weight
88
What aromas is associated with low levels of ethyl acetate?
fruity & floral
89
What are the six principal acids in wine?
1. tartaric acid 2. malic acid 3. citric acid 4. lactic acid 5. acetic acid 6. succinic acid
90
What is the most prevalent acid in both grapes & wine?
tartaric acid
91
Where are phenolics of a grape found primarily?
skin and seeds
92
Define polymerize.
when phenolic compounds combine into longer molecule chains over time
93
What does tartaric acid form at low temperatures?
tartrates or "wine diamonds"
94
What phenolic compound are yellow pigments found in white wines?
flavonols
95
What phenolic compound forms part of the backbone of red wines?
tannins
96
What is the approximate concentration of water in wine?
80 - 90%

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