Common Elements In Winemaking And Maturation Flashcards

1
Q

Bitter oils and tannins are found in which part of the grape?

A

The seeds

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2
Q

What is the waxy surface covering the grape skin called, and what does it contain?

A
  • The bloom

- Yeast

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3
Q

What is the largest single component of a grape’s pulp?

A

Water

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4
Q

What are the two most abundant forms of acid found in the grape’s pulp?

A

1) Tartaric acid

2) Malic acid

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5
Q

What are the 3 sources of tannin within a grape?

A
  • Skin
  • Seeds
  • Stem
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6
Q

What 3 components do grape skins contain?

A
  • Flavour compounds
  • Tannins
  • Colour compounds
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7
Q

What are 2 ways to counter oxidation?

A

1) Use of antioxidants such as sulfur dioxide

2) Taking precautions to oxygen contact to a minimum

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8
Q

Why does picking grapes at night help counter oxidation?

A

It is cooler - chemical reactions occur more slowly at lower temperatures, so the effect of oxygen contact is reduced

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9
Q

What 2 names are used to call the process of making wine with as little oxygen exposure as possible?

A

1) Protective winemaking

2) Anaerobic winemaking

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10
Q

Will wines made in a protective style benefit from oxygen contact during maturation?

A

Rarely, if ever

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11
Q

How would you store and mature wines which had been made in a protective style?

A

In inert airtight tanks or vats which are kept completely full

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12
Q

What 2 materials are inert maturations vessels made from?

A

1) Stainless steel

2) Cement lined with epoxy resin

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13
Q

Where would aerobically-matured wines be stored?

A

Wooden vessels, usually made from oak

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14
Q

Why is oak an ideal storage and maturation material for many wines?

A

It is watertight but not airtight

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15
Q

What happens with oxidative ageing to the colours of:

1) Red wine
2) White wine

A

1) Become paler and gain a hint of brown

2) Become deeper and gain a hint of orange

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16
Q

Which has a greater oxidative effect, a small or large oak barrel?

Why?

A

A small barrel, because they present a proportionately larger surface area of wood to the wine

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17
Q

How long are wines usually kept in barrique for?

A

Rarely longer than 2 years, as their oxidative effect is relatively strong

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18
Q

How can the effect of oxygen be enhanced whilst using a wooden vessel?

A

By not filling the container completely

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19
Q

Name 3 wines which are deliberately oxidative in style

A
  • Oloroso Sherry
  • Tawny Port
  • Rutherglen Muscat
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20
Q

What happens to wine when it gets too much exposure to oxygen?

A

It can lose much of its fresh fruit flavour and smell stale and vinegary

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21
Q

What two uses does sulfur dioxide have in the winery?

A

It acts as an antioxidant and an antiseptic

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22
Q

What is strictly controlled by law because it can be toxic?

A

Upper levels of SO2 in wine

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23
Q

Why is it preferable to keep SO2 levels as low as possible?

A

High levels can make the wine seem harsh and lacking in fruit

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24
Q

What does it mean when SO2 becomes ‘bound’?

A

It loses the ability to have any further protective effect against oxygen

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25
Q

Why must levels of SO2 be constantly monitored and replenished?

A

It becomes bound as it protects the grape juice and wine against oxygen, so needs topping up

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26
Q

Why is SO2 used to kill off the many strains of yeast and bacteria which are found in wines?

A

They can cause unwanted flavours in the wines

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27
Q

Why doesn’t SO2 kill off the principal yeast involved in fermentation?

A

The levels used are toxic to other species, but these commercial yeasts are tolerant to those levels

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28
Q

Of what are the vast majority of wooden vessels made?

A

Oak

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29
Q

What are the 2 advantages of using oak for maturation?

A

1) They allow a small amount of oxidation, developing tertiary aromas
2) The wine can extract tannin and flavours from the oak

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30
Q

What do oak tannins add to red and white wines?

3 points

A

1) Structure
2) Textural complexity
3) Aromas such as toast, vanilla, smoke and cloves

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31
Q

Why is hygiene an issue with oak vessels?

A

It is difficult to keep them completely free of yeasts, bacteria and moulds; tainted wood can ruin a wine.

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32
Q

What are the 4 factors to consider when choosing an oak vessel for maturation?

A

1) Species and origin of the oak
2) Size
3) Production method of the barrel
4) Age

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33
Q

From which 2 continents does the majority of the oak used in winery vessels originate?

A

Europe and North America

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34
Q

Which 3 European countries produce the most oak for barrels?

A
  • France
  • Hungary
  • Russia
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35
Q

What size is a barrique?

A

225 litres

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36
Q

What size is a pièce?

A

228 litres

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37
Q

How large can the biggest oak vessels be?

A

In excess of 2000 litres

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38
Q

Why do smaller oak vessels have a much greater effect on the wine than larger ones?

A

Because in smaller vessels, much more of the wine is in contact with the surface area of the barrel

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39
Q

What does toasting a barrel do to the tannins and flavour compounds in the oak?

A

It will transform them, giving notes of sweet spice and toast

40
Q

What does ‘toasting’ a barrel mean?

A

It is part of the production process - the staves are heated over a flame so that they can be bent into shape.

41
Q

What is the ‘level’ of toasting in a barrel?

A

The temperature and length of heat exposure during toasting

42
Q

What diminishes each time an oak barrel is used?

A

The effect of the toasting

43
Q

After how many uses would a barrel be expected to impart very little flavour or tannin?

A

On its fourth use

44
Q

Why might a producer choose not to use new oak barrels?

A

If the strong flavours of new oak were not desirable for a particular wine

45
Q

What are 2 alternative methods for adding oak aromas and tannins to wine, other than barrel ageing?

A
  • Adding small planks of oak (staves)
  • Adding small oak chips

Both could be added during fermentation or maturation, and to inert vessels

46
Q

Why might a producer use oak staves or chips?

A

It is much cheaper than using casks

47
Q

How can the oxidative effects of barrel ageing be replicated in inert vessels?

A

By adding small, controlled quantities of oxygen

48
Q

Why are some winery vessels referred to as ‘inert’?

A

They do not add flavour to the wine or allow oxidation

49
Q

Which 2 materials are most inert vessels made from?

A
  • Stainless steel

- Concrete

50
Q

Are inert vessels ever used for maturation?

A

There would be no point, as they would not impart new flavours - they are often used to temporarily store finished wines prior to bottling.

51
Q

What are 3 advantages of using stainless steel for vessels?

A
  • Easy to keep clean
  • Can be made in any shape and size
  • Can incorporate temperature control mechanisms
52
Q

What are the 2 types of temperature control mechanism used in stainless steel vessels?

A
  • Sleeves on the outside of the vessels

- Internal coils through which cold or hot liquid can be circulated

53
Q

What are concrete vessels usually lined with, and why?

A

Epoxy resin - it is inert and provides a waterproof barrier

54
Q

Why have many concrete tanks been replaced by stainless steel?

A

They can be less easy to clean and maintain

55
Q

Why do some winemakers prefer concrete over steel vessels?

A

The thick concrete shells help regulate temperature during fermentation without the need for expensive temperature control equipment

56
Q

Other than concrete and steel, what is another type of inert vessel which can be used for storage and maturation in the winery?

A

Glass bottles

57
Q

When do grapes usually receive their first dose of SO2?

A

As they arrive at the winery

58
Q

Why might grapes be individually checked on a sorting table when they arrive at the winery?

A

To eliminate unripe or rotten grapes - for premium wines only

59
Q

Name two optional processes right after grape reception.

A

1) Destemming

2) Crushing

60
Q

Why might grapes arrive in the winery without stems?

A

If they have been machine harvested

61
Q

Do most winemakers prefer to keep or remove the stems?

A

Most choose to remove them

62
Q

How is destemming usually carried out once in the winery?

A

In a machine which can subsequently crush the grapes

63
Q

What happens to grapes when they are crushed?

3 points

A
  • The skin breaks
  • A quantity of free run juice is liberated
  • The seeds are not damaged
64
Q

What happens if grape seeds are crushed?

A

They release bitter oils and tannin

65
Q

What is ‘pressing’?

A

The separation of the liquid and solid constituents of the grape.

66
Q

When does pressing typically occur for:

1) White wines
2) Red wines

A

1) Before fermentation

2) After fermentation

67
Q

Should seeds be damaged or undamaged during pressing?

A

Undamaged - pressing should be gentle

68
Q

What is a ‘basket press’ and how does it work?

A

The traditional style of vertical wine press - pressure is applied to the grapes from above using a plate which is raised & lowered with a screw or lever.

69
Q

In which region do many wineries still widely use traditional basket presses?

A

Champagne

70
Q

What are the two main types of wine press?

A
  • Vertical basket press

- Pneumatic press

71
Q

How do pneumatic presses work?

A

A rubber tube is inflated inside a perforated, horizontal stainless steel cylinder - the grapes are pressed between them and the juice runs off.

72
Q

Why are pneumatic presses more effective than vertical presses?

A

They make it possible to apply pressure over a larger area, in a more controlled manner.

73
Q

Why are some pneumatic presses built within a closed tank?

A

To minimise oxygen contact with the juice

74
Q

What is the name for the different pressings into which grape juice may be separated during the pressing process?

A

Fractions

75
Q

When can adjustments be made to one or more of the major components of the grape juice or wine?

A

Before, during or after fermentation

76
Q

What is ‘must’?

A

Grape juice

77
Q

What is the ‘must weight’?

A

The level of sugar in the grape juice

78
Q

Why might a winemaker decide to carry out enrichment?

A

If there is insufficient natural sugar in the grapes to give the wine a satisfactory level of alcohol.

79
Q

Would enrichment be needed for wines produced in hot or cool climates?

A

Cool climates, as the acidity in the grapes would be high and the sugar levels low at harvest

80
Q

What is the process of enrichment?

A

Increasing sugar levels in the grape juice by adding RCGM either before or during fermentation.

81
Q

How does enrichment increase the level of alcohol in a final wine?

A

It adds sugar, so there is more sugar available for the yeast to convert to alcohol.

82
Q
  • What does RCGM stand for?

- What is RCGM?

A
  • Rectified Concentrated Grape Must

- A colourless, odourless syrupy liquid made from grape juice

83
Q

When is RCGM added to wine in the enrichment process?

A

Before or during fermentation

84
Q

Why is enrichment forbidden or strictly controlled in many parts of the world?

A

If the process is abused, it can produce inferior wine which tastes hard and thin because there are insufficient flavours to balance the artificially elevated alcohol.

85
Q

What is chaptalisation?

A

Similar to enrichment, it is a process to increase sugar and thus alcohol levels in a wine before or during fermentation - but instead of RCGM, sugar from sources other than grapes is used (e.g. sugar beet)

86
Q

If sugar beet were added to a fermenting wine to increase final alcohol levels, would this be enrichment or chaptalisation?

A

Chaptalisation - the sugar is from a source other than grapes.

87
Q

Other than enrichment and chaptalisation, what is a 3rd method of increasing sugar levels during wine production?

A

Removing water from the juice to concentrate the sugars.

88
Q

Why is removing water from the juice to concentrate sugars not a particularly effective method of increasing alcohol?

(2 points)

A

1) All other elements in the juice are also concentrated - including tannins, acids, flavour compounds and faults.
2) Volume of the juice is reduced so less wine can be made and sold.

89
Q

If too much sugar is added to the juice, how can this be corrected?

A

It is very difficult to remove sugar from the juice, so modern machinery is used to remove alcohol from the wine once fermentation is complete.

90
Q

What is the name of the process by which acid is added to grape juice?

A

Acidification

91
Q

Why might acid need to be added to grape juice?

A

If, during ripening, grape acids fall too far.

92
Q

Would chaptalisation/enrichment be needed for grapes grown in a cool or a hot climate?

Why?

A
  • Cool climate

- The grapes may struggle to reach sufficient levels of sugar ripeness in cooler temperatures

93
Q

Would acidification be needed for grapes grown in hot or cool climates?

Why?

A
  • Hot climates

- The grapes may convert too much acid to sugars in hot temperatures, which would lead to a flabby and unbalanced wine

94
Q

What is normally added to the wine during acidification?

A

Powdered tartaric acid

95
Q

Generally speaking, where in Europe is acidification allowed?

A

Warmer regions only

96
Q

Where is deacidification common?

A

In cooler climate regions where acid levels may not have fallen sufficiently in ripening grapes

97
Q

What happens in the process of deacidification?

A

An alkali is added to the juice to neutralise excess acid.