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CWE > Wine Chemistry > Flashcards

Wine Chemistry Flashcards

1
Q

What is Succinic acid?

A

Succinic acid is a minor component in grapes and a byproduct of fermentaion. It has a sharp, slightly bitter, salty flavor.

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2
Q

What are the five major components of wine?

A

Water
Alcohol
Acid
Sugar
Phenolic Compounds

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3
Q

What percentage of wine is normally water?

A

80-90%

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4
Q

Which alcohol is the main alcohol component in wine?

A

Ethyl Alcohol (ethanol)

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5
Q

What is another name for Ethyl Alcohol?

A

Ethanol

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6
Q

What types of alcohol are found in wine?

A

Ethyl Alcohol (primary)
Smaller Amounts: Glycerol, Methyl Alcohol (methanol), fused alcohols (fusel oils) or higher alcohols.

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7
Q

What is a volatile compound?

A

A compound that evaporates easily.

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8
Q

What percentage of a wine do acids make up?

A

.5-.75%

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9
Q

What is the most prevalent acid in wine?

A

Tartaric

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10
Q

Which acids are typically found in grapes?

A

Tartaric Acid
Malic Acid
Citric Acid (Minute amounts)
Succinic Acid (Minor component)

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11
Q

What acids are from fermentation?

A

Lactic Acid
Acetic Acid
Succinic Acid

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12
Q

What does Total Acidity measure?

A

The volume of all acids in a wine.

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13
Q

Why is pH often used as a measurement for acidity rather than Total Acid?

A

Total acidity measure the volume of all acidities in a wine. Some acids have a more acidic taste than others, and some are stronger. The pH level is the combined chemical strength of the acids present.

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14
Q

What is the normal pH range for wine?

A

2.9-3.9

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15
Q

Does a wine with a lower pH taste more or less acidic than one with a higher pH?

A

A lower pH tastes more acidic.

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16
Q

What is the percentage of sugar in most grapes at harvest?

A

15-28%

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17
Q

What are the two main types of sugar found in grapes.

A

Glucose and Fructose

18
Q

What are phenolic compounds?

A

Molecules present in wine in minute quantities, and have a major impact on the sensory profile of a wine.

19
Q

What is a monosaccharide, and which sugars in wine are monosaccharides?

A

A simple sugar. Both Glucose and Fructose are simple sugars.

20
Q

What are the five main phenolics found in wine?

A

Anthocyanins
Flavonols
Tannins
Vanillin
Resveratrol

21
Q

What is an Anthocyanin?

A

A phenolic compound that gives red wine its color.

22
Q

How is the color of red wine affected by acid?

A

More acidic wines appear redder, less acidic wines look bluer.

23
Q

What is a Flavonol?

A

A phenolic compound that is a yellow pigment. It increases in grapes with increased exposure to sunlight.

24
Q

What happens to certain phenolic compounds over time?

A

They polymerize, form longer chains and become sediment.

25
Q

What is an Aldehyde?

A

Oxidized alcohols that are formed when wine is exposed to air.

26
Q

What are two examples of wine that encourage the formation of Aldehydes?

A

Sherry and Madeira.

27
Q

What is the most common Aldehyde?

A

Acetaldehyde.

28
Q

What is acetaldehyde?

A

An aldehyde formed by the oxidation of ethanol.

29
Q

What is an esther?

A

A molecule formed by the joining of an acid and alcohol.

30
Q

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

A

Esthers

31
Q

What is Ethyl Acetate?

A

The ester of acetic acid and ethanol.

32
Q

What aromas does Ethyl Acetate impart?

A

At low concentrations, fruity, flowery aromas. At high concentrations, faulty aromas of nail polish remover, varnish, or glue.

33
Q

Are esters considered a fault?

A

At high enough concentrations, the ester aromas may be faulty off-odors.

34
Q

What effect do dissolved gases have on wine?

A

Dissolved gases promote many chemical reactions through oxidation, which may be beneficial or to be avoided depending on the wine.

35
Q

What is a common dissolved gas found in wine?

A

Carbon dioxide is found in at least small quantities in all wines as a by-product of fermentation.

36
Q

What are the labeling requirements regarding Sulfites in the US?

A

If a wine contains more than 10 ppm of sulfur dioxide it must display the contains sulfites warning on the label.

37
Q

What are the benefits of sulfur in winemaking?

A

It is an antioxidant and an antibacterial agent.

38
Q

What are methoxypyrazines?

A

Also called a pyrazines, these are the flavor compounds that result in herbaceousness in wines.

39
Q

What is Rotundone?

A

A key aroma compound responsible for the “spicy” or “peppery” aroma in some red wines, particularly Syrah from cooler climates. Also found in Grüner Veltliner.

40
Q

What is Rancio?

A

A tasting term referring to a fortified wine or Vin Doux Naturel that was deliberately maderized.

41
Q

What are Terpenes?

A

Flavor compounds associated with the floral and citrus aromas found in wines such as Muscat, Gewürztraminer, and Riesling.

42
Q

What is Ullage?

A

It its the process of evaporation of wine held in a barrel. Head space at the top of the barrel is also called the ullage.

CWE (34 decks)

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