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CSW Study Guide > Ch. 1: Wine Composition & Chemistry > Flashcards

Ch. 1: Wine Composition & Chemistry Flashcards

1
Q

Major components of wine

A

Water

Alcohol

Acid

Sugar

Phenolic Compounds

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2
Q

Wine Component- Water

A

Wine is typically 80-90% water

Uncommon, but sometimes a winemaker adds water to dilute grape juice or if potential components are beyond desirable levels

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3
Q

Wine Components- Alcohol

A

Usually 10-15% of wines volume

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4
Q

Ethyl Alcohol (Ethanol)

A

Primary result of alcoholic fermentation and main alcohol component of wine

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5
Q

Other Types of Alcohol that Occur in Smaller Amounts

A

Glycerol

Methyl Alcohol (Methanol)

Fusel Alcohol (Fusel oils)

Higher Alcohols

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6
Q

Weight (Body)

A

Tactile sensation of wine as it rests on the palate

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7
Q

Wines with Higher Alcohol Have…

A

Heavier weight

Tears or legs after swirling the glass

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8
Q

Wine Component- Acid

A

Gives wine much of its structure, balance, and thirst-quenching refreshment

Usually makes up 0.5-0.75% of wines volume

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9
Q

Tartaric Acid

A

Most prevalent of acids in both grapes and wine

Strongest pH

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10
Q

Wine Diamonds

A

Crystals formed by tartaric acid

Won’t redissolve into liquid

Wine will become less acidic

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11
Q

Malic Acid

A

Sharp-tasting acid associated with green apples

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12
Q

Low Levels of Malic Acid

A

Wines made from over ripe grapes or grapes grown in hot climates

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13
Q

Malolactic Fermentation

A

Can lessen high levels of malic acid

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14
Q

Citric Acid

A

Not usually a normal component of wine

Has no sensory impact on majority of wine

Sometimes added to increase total acidity in a wine

Distinctive citrus flavors makes citric acid generally unsuitable for wine

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15
Q

Lactic Acid

A

Not found in grapes

Created in wine by lactic acid bacteria

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16
Q

Malolactic Fermentation

A

During fermentation

Lactic acid bacteria converts malic acid into lactic acid in the optimal winemaking process

Wines that undergo malolactic fermentation tend to be softer, smoother with creamy texture

Buttery aroma

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17
Q

Acetic Acid

A

Found in most types of vinegar

Low levels typically created during fermentation

Volatile

Evaporates and joins aroma of wine

Adds complexity

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18
Q

Acetobacter

A

Harmful bacteria that causes chemical reaction between ethanol and oxygen

Can make wine vinegary and undrinkabke

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19
Q

Succinic Acid

A

Minor components of grapes

By-product of normal fermentation

Sharp, Slightly bitter, slightly salty flavor

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20
Q

Total Acidity

A

Volume of all acids in wine

More acid equates to more acidic taste

21
Q

pH

A

Represents combined chemical strength of acids that present

Wines usually measure between 2.9 and 3.9 on logarithmic pH scale

Lower the pH, the stronger the acid content

22
Q

To Get a Complete Picture of Wine’s Acidity…

A

You need to know both TA and pH

23
Q

Winemakers Emphasis on pH

A

Gives indication of stability

Plays role in determining sulfur additions

24
Q

Sugar

A

Grapes typically contain 15-28% sugar at harvest

25
Two Sugars in Grapes
Glucose and fructose
26
Glucose and Fructose
Highly fermentable monosaccharides (simple sugars)
27
Yeast Role in Fermentation
Converts glucose and fructose into ethanol Turns grape juice into wine If yeast completes conversion, wine will be fermented to dryness Fermentation generally stopped to prevent complete dryness
28
Residual Sugar
Remaining sugar
29
Amount of Residual Sugar
Wines with less sugar = dry Depending on amount of residual sugar Off dry Medium sweet Sweet Residual sugar can add weight and viscosity Dessert wines - 24% or greater residual sugar
30
Phenolic Compounds
Various molecules present in many wines Minute quantities Major impact on sensory profile
31
Types of Phenolic Compounds
Anthocyanins Flavolins Tannins Vanillin Resveratrol
32
Anthocyanins
Give red wine it’s color Ranges from blue to purple to red Color influenced by anthocyanins and acidity More acidic = redder Less acidic = bluer
33
Flavonols
Yellow pigments in white wines Increase in grapes exposed more to sunlight Sunnnier climates have wines with more golden color
34
Tannins
Bitter compounds in grape skins, seeds, & stems Also in oak and oak barrels Backbone of big red wines Natural preservative - helps protect red wine from oxidation during aging
35
Vanillins
Aromatic compound in oak Imparts vanilla scent to barrel-aged wines
36
Resveratrol
Beloved to have several health benefits Concentrated in skins and seeds
37
Phenolic Compounds that Polymerize
Tannins & pigments Eventually become too heavy and stay suspended in liquid May drop out as sediment
38
Other Wine Components
Aldehydes Esters Dissolved gasses Sulfites
39
Aldehydes
Oxidized alcohols formed when wine exposed to air Also if opened too long or exposed to heat
40
Maderized Wine
Exposed to excessive oxygen during production or storage
41
Acetaldehyde
Most common aldehyde Formed by oxidation of ethanol Gives fino Sherries distinctive aroma
42
Esters
Molecules that result from joining an acid and an alcohol Largest group of odiferous compounds in wine
43
Ethyl Acetate
Most common ester Eater of acetic acid and ethanol Low concentration = fruity, flowery aroma High concentration = Nail polish remover, varnish, glue
44
Dissolved Gases
Eventually present in any liquid Not significant concentration Oxygen & carbon dioxide
45
Dissolved Oxygen
Promotes oxidation Winemakers add sulfur to absorb any free oxygen molecules before wine is harmed
46
Carbon Dioxide
Routinely found in wine Gives sparkling wine it’s bubbles By-product of fermentation Keeps wine fresh & lively in mouth Promotes release of aromatic compounds
47
Sulfites
Based on sulfur Keeps wine stable during fermentation Produced in minute quantities All wines have trace amounts of sulfites Making wine without sulfites is challenging
48
US Regulations (Sulfites)
Wine with more than 10 parts per million sulfur dioxide “Contains Sulfites” on label

CSW Study Guide (9 decks)

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