Wine composition and chemistry Flashcards

1
Q

What are the major components of wine

A

Water, Alcohol, Sugar, Acid & Phenolic compound

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2
Q

What compound is present in wine by extensive ageing or contact with Lees

A

Yeast or proteins

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3
Q

where does the water in wine come from & what is the % of water present in wine

A

Water comes from grapes and the wine consists of 80-90% water

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4
Q

What is the most prevalent ingredient in wine after water

A

Alcohol

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5
Q

How much % of alcohol is present in wine

A

10-15%

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6
Q

What is the primary alcohol in wine and name other alcohol present in wines

A

Primary alcohol is Ethyl alcohol(ethanol)

Other alcohol- glycerol, methyl alcohol, fusel alcohol

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7
Q

What does the term volatile mean

A

A substance that evaporates easily

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8
Q

Wines with higher alcohol are heavier than wines with low alcohol. True or False

A

True

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9
Q

What are wine legs

A

Tears of wine that form on the edge of the glass when swirled, result of high level alcohol in wine

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10
Q

How does acid help white wine

A

It gives wines its structure, balance and thirst quenching refreshment

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11
Q

Acids make up _____ % of a wines volume

A

0.5-0.75%

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12
Q

Name all the acids present in wine

A

Tartaric, malic, citric, lactic, acetic, succinic

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13
Q

Name the fermentation acids

A

Lactic, succinic, acetic

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14
Q

Acid with sharp, slightly bitter and salty flavor

A

Succinic

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15
Q

Acid associated with green apples

A

Malic

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16
Q

Level of malic acid reduces as the grape ripens.True or False

A

True

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17
Q

What acid requires special equipment to measure and is not a normal component of wine

A

Citric

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18
Q

Premium wines have citric acid added to increase TA. True or False

A

False

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19
Q

Which bacteria is responsible for MLF in winemaking

A

Lactic acid bacteria

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20
Q

Define MLF

A

A process in winemaking in which malic acid is converted to softer-tasting lactic acid

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21
Q

MLF gives the wines its _____

A

Creamy texture and a buttery aroma

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22
Q

______ is found in vinegar and is also a created during fermentation

A

Acetic acid

23
Q

higher concentrations of acetic acid lead to

A

chemical reaction between ethanol and oxygen

24
Q

Name the grape acids

A

Tartaric, malic, citric and succinic

25
Q

What is total acidity(TA)

A

Total volume of all acids present in wine

26
Q

What is pH

A

Combined chemical strength of all acids

27
Q

in terms of pH, wines usually measure between

A

2.9-3.9

28
Q

Wine with pH 3.4 will be more acidic than wine with pH 2.9

True of False

A

False

29
Q

During harvest, grapes contain ______ amount of sugar

A

15-28%

30
Q

What are the 2 forms of sugars present in grape

A

Glucose & Fructose

31
Q

Can dry wines contain trace amount of sugar

A

yes

32
Q

Residual sugar in wine adds to what

A

weight or body

33
Q

Dessert wines can contain upto ____ % of residual sugar

A

24%

34
Q

What are phenolic compounds

A

A large category of various molecules present in many wine

35
Q

Minute quantities of phenolics in wine can have a major impact on sensory profile of wine. True or False

A

True

36
Q

Name all the Phenolic compounds

A

Anthocyanins, Flavonols, Tannins, Vanillin, Resveratrol

37
Q

Name other molecules/components present in wine

A

Aldehydes, Esters, Dissolved gases, Sulfites

38
Q

Compound that gives red wine its colour

A

Anthocyanin

39
Q

Compound that gives white wines its colour

A

Flavonols

40
Q

_____ is a compound present in red wines and is a backbone for big red wines

A

Tannin

41
Q

Compound responsible for the vanilla scent in barrel aged wines

A

Vanillin

42
Q

Compound known to have health benefits

A

Resveratrol

43
Q

What are aldehydes

A

Oxidized alcohols formed when the when the wine is exposed to air

44
Q

Which styles of wine encourage formation of aldehydes in their winemaking technique

A

Sherry & Madeira

45
Q

What is acetaldehyde

A

Most common aldehyde formed by the oxidation of ethanol

46
Q

What are esters

A

They are molecules that result from joining of an acid and alcohol

47
Q

What is the ester of acetic acid and ethanol known

A

Ethyl acetate

48
Q

Higher quantities of ethyl acetate impart faulty aromas of

A

nail polish remover, varnish or glue

49
Q

low quantities of ethyl acetate impart aromas of

A

fruity and floral aromas

50
Q

what helps remove molecules of oxygen from wine

A

Sulfur

51
Q

What does dissolved oxygen do in wine

A

Dissolved oxygen promotes oxidation

52
Q

How does CO2 help wine

A

CO2 keeps wine fresh and lively, promoting release of aromatic compounds

53
Q

Why is sulfur added in wines

A

It is an important preservative used to keep wines stable after fermentation. It is an antioxidant and anti bacterial agent

54
Q

When do the winemakers need to add “Contains Sulfites” on their label

A

When the content is more than 10 parts per million(ppm)