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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
Q

Two Sugars in Grapes

A

Glucose and fructose

26
Q

Glucose and Fructose

A

Highly fermentable monosaccharides (simple sugars)

27
Q

Yeast Role in Fermentation

A

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
Q

Residual Sugar

A

Remaining sugar

29
Q

Amount of Residual Sugar

A

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
Q

Phenolic Compounds

A

Various molecules present in many wines

Minute quantities

Major impact on sensory profile

31
Q

Types of Phenolic Compounds

A

Anthocyanins

Flavolins

Tannins

Vanillin

Resveratrol

32
Q

Anthocyanins

A

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
Q

Flavonols

A

Yellow pigments in white wines

Increase in grapes exposed more to sunlight

Sunnnier climates have wines with more golden color

34
Q

Tannins

A

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
Q

Vanillins

A

Aromatic compound in oak

Imparts vanilla scent to barrel-aged wines

36
Q

Resveratrol

A

Beloved to have several health benefits

Concentrated in skins and seeds

37
Q

Phenolic Compounds that Polymerize

A

Tannins & pigments

Eventually become too heavy and stay suspended in liquid

May drop out as sediment

38
Q

Other Wine Components

A

Aldehydes

Esters

Dissolved gasses

Sulfites

39
Q

Aldehydes

A

Oxidized alcohols formed when wine exposed to air

Also if opened too long or exposed to heat

40
Q

Maderized Wine

A

Exposed to excessive oxygen during production or storage

41
Q

Acetaldehyde

A

Most common aldehyde

Formed by oxidation of ethanol

Gives fino Sherries distinctive aroma

42
Q

Esters

A

Molecules that result from joining an acid and an alcohol

Largest group of odiferous compounds in wine

43
Q

Ethyl Acetate

A

Most common ester

Eater of acetic acid and ethanol

Low concentration = fruity, flowery aroma

High concentration = Nail polish remover, varnish, glue

44
Q

Dissolved Gases

A

Eventually present in any liquid

Not significant concentration

Oxygen & carbon dioxide

45
Q

Dissolved Oxygen

A

Promotes oxidation

Winemakers add sulfur to absorb any free oxygen molecules before wine is harmed

46
Q

Carbon Dioxide

A

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
Q

Sulfites

A

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
Q

US Regulations (Sulfites)

A

Wine with more than 10 parts per million sulfur dioxide

“Contains Sulfites” on label

CSW Study Guide (9 decks)

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