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WSET 3 > 7 - Common Elements in Winemaking and Maturation > Flashcards

7 - Common Elements in Winemaking and Maturation Flashcards

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1
Q

Constituent parts of grapes. Short description of each

A
  • seed & stems: Both contain tannins. Seeds also contain high levels of bitter oils
  • bloom: The waxy surface that covers the skins of the grapes and contains yeast that can be used to ferment the wine
  • skin: Contains a high concentration of flavour compounds. Also contain tannins and colouor compounds.
  • pulp: Water, sugar, acids (tartaric, malic)
  • tannins: A large number of chemical compounds are classed as tannin. At véraison they taste very bitter and astringent and, as the grapes ripen, the level of bitterness and astringency falls. Oak can also contribute some tannins to both red and white wines.
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2
Q

different winemaking approaches

A
  1. control each part of the wm-process as much as possible (tailor to stylistic goal)
  2. hands-off aproach (monitor, but intervent as little as possible) –> often have very different taste profile. Sometimes referred to as ‘natural wines’
  • two ends of a spectrum
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3
Q

5 common elements throughout winemaking and maturation
(not steps!)

A
  • oxygen
  • sulfur dioxide
  • oak vessels
  • oak alternatives
  • inert vessels
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4
Q

Oxygen

A
  • gas
  • can react with grape juice & component parts of a wine –> oxidation
  • sometimes positive and sometimes negative
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5
Q

How to avoid oxygen during winemaking

A
  • use antioxidants (ie Sulfur)
  • pick grapes at night (cooler –> slower reactions)
  • chilled until winery
  • protective/anaerobic wm: airtight winery equipment filled with CO2 or N2 before use
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6
Q

argue against protective/anaerobic winemaking:

A

Bland and uninteresting wine. Oxygen helps develop complexity and character in a wine.

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7
Q

Mature in oak if wm is done without oxygen?

A

Wines that have been protected from oxygen during winemaking rarely if ever benefit from any contact with oxygen during maturation

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8
Q

how can wines be matured anaerobic?

A
  • inert airtight tanks or vats
  • completely full
  • stainless steel
  • cement lined with epoxy resin
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9
Q

Wines matured aerobically
(vessel etc, what happens to the wine, too much)

A
  • wooden vessels (normally oak)
  • watertight but not airtight (small amounts of oxygen react with the wine)
  • size (surface/volume) & length of time
    225L barriques, <2years
  • not completely full (ie fortified wine, Oloroso Sherry, Tawny Port, Rutherglen Muscat)
    /
  • red –> paler, hint of brown. Soften tannins
  • white –> deeper, hint of orange
  • more complexity , primary fruit flavours fade, tertiary develop
    /
    too much –> damaging
  • lose fresh fruit flavour, smell stale
  • bacteria –> vinegar
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10
Q

Sulfur Dioxide (SO2)

A
  • antioxidant & antiseptic
  • protect freshly harvested grapes & adjust levels throughout wm process
  • upper levels are strictly controlled by law (toxic, allergic reactions)
  • produced naturally in fermentation
  • too high levels: wine can seem harsh & lacking in fruit
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11
Q

SO2 as antioxidant

A
  • protect grape juice & wine from the effects of oxidation
  • loses the ability to have any further protective effect (‘bound’)
  • levels: constant monitoring & replenish
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12
Q

SO2 as antiseptic

A
  • toxic to many strains of yeast & bacteria
  • the pricipal yeast involved in alcohol fermentation is able to tolerate levels of SO2 that are toxic to these other species
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13
Q

What does a wine get from oak vessels?

A
  • develop tertiary aromas through oxidation
  • tannins: give more structure and increse textural complexity
  • aromas and flavours (toast, vanilla, smoke, cloves)
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14
Q

challenges with oak vessels

A
  • Hygiene: difficult to keep wooden vessels completely free of yeast, bacteria and moulds
  • Tainted wood
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15
Q

4 important factors to consider related to oak vessels

A
  1. Species & origin: different characteristics
    Most European or American. European oak has broadly similar char., but some forests are considered to produce the finest oak.
  2. Size: small barrels (225L barrique, 228L piece) vs large vessels (can be >2000L)
  3. Production:
    Toasting, temp.&length of heat exposure. Transform tannins & flavour compounds, notes of sweet spice & toast.
  4. Age: new vs old. 4th use –> little flavour/tannin. More subtle oak flavours if not new
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16
Q

Oak alternatives

A
  • staves & chips
  • adding small amount of oxidation to wine vessel
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17
Q

Inert Winery vessels
- why use?
- 3 examples

A
  • do not add flavour or allow oxidation
  1. stainless steel
  2. concrete vessels
  3. glassbottles
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18
Q

stainless steel vessels

A
  • easy to keep clean
  • any shape & size
  • incorporate temperature control mechanisms
    (sleeves on the outside of the vessels or internal coils through which cold or hot liquid can be circulated)
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19
Q

Concrete vessels

A
  • usually lined with epoxy resin (inert, waterproof barrier)
  • less easy to clean & maintain
  • thick concrete shells help regulate temperature without need of expensive temperature control equipment
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20
Q

Main steps in the wm (6)

A
  1. Grape processing
  2. Fermentation and conversion
  3. Pre-bottling maturation & blending
  4. Clarification
  5. Stabilisation
  6. Packaging
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21
Q

Grape processing
(steps)

A
  1. Grape Reception
  2. Destemming and Crushing
  3. Pressing
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22
Q

Grape Reception

A
  • usually a dose of SO2
  • sorting table (individually checked for premium wines)
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23
Q

Destemming & Crushing

A
  • both optional processes
  • machine-harvest: come without stems
  • usually machine for desteming & crushing
  • juice from crushing: free run juice
  • do not damage seeds –> bitter oils & tannins
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24
Q

Pressing

A
  • separates liquid & solid constituents
  • white: before fermentation, red: after fermentation
  • seeds should remain undamaged
  • fractions –> taste & blend
  • press wine

Types:
- traditional: vertical ‘bascet’ presses (now often automated)
still used particularly in the Champagne region
- pneumatic presses: inflatable rubber tube within a perforated horizontal ss cylinder
–> pressure over a larger area, in a controllable way
–> some within closed tankt (without O2)

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25
Q

When to do adjustments to the grape juice or wine

A

before, during or after fermentation
(what is legally permitted varies from region to region)

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26
Q

why may sugar-adjustments be needed in cooler climates?

A

may be insufficient natural sugar in the grapes to give the wine a satisfactory level of alcohol

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27
Q

must weight

A

level of sugar in the juice

28
Q

how to increase alcohol in a wine

A
  • enrichment (add sugar)
  • remove water from the juice (conc. sugar)
29
Q

enrichment
(what/how/when, where, too much)

A
  • increasing sugar levels in the juice
  • RCGM added before or during fermentation
  • raising the level of alcohol in the final wine (fermentation)
  • Forbidden many places, strictly controllet where permitted
  • Too much: taste hard & thin (insufficient flavours to balance alchol)
30
Q

RCGM

A

Rectified Concentrated Grape Must
- colourless
- odourless
- syrupy liquid

31
Q

chaptalisation

A

sugar from other sources than grapes is added (sugar beet)

32
Q

water removed from the must

A
  • concentrates the sugars
  • conc. tannins, acids, flavour compounds & any faults
  • reduces the volume of the juice (less wine)
33
Q

how to reduce alcohol in a wine

A
  • difficult to remove sugar from the juice
  • modern machinery can remove alcohol from the wine after fermentation is complete
34
Q

Acidification
(what, how, where)

A
  • increasing acid levels
  • normally by addition of tartaric acid (powder form)
  • Europe: permitted in warmer regions only
  • Common in many warm and hot regions around the world
35
Q

Deacidification
(what, where, how)

A
  • reducing acid levels
  • more common in cooler climate regions
  • neutralised by addition of an alkali
36
Q

Alcoholic fermentation

A
  • conversion of sugar (glucose) into alcohol & CO2 by yeast
    C6H12O6 –> 2 C2H2OH + 2 CO2
  • by-products: heat & flavour compounds
37
Q

yeast species responsible for the majority of wine fermentations
(which, why)

A
  • Saccharomyces cerevisiae
  • tolerance of relatively high levels of alcohol and SO2
38
Q

temperature for fermentation

A
  • 5-35C
  • white: 12-22C
  • red: 20-32C
39
Q

what can stop fermentation? (9)

A
  • too low or too high temperature
  • too high sugar level and/or alcohol
  • all sugar is consumed
  • run out of nutrients (other than sugar)
  • adding SO2 or grape spirit
  • yeast removed by filtration (typically after chilling below 5C)
40
Q

2 important ways to control fermentation

A
  1. yeast
  2. temperature
41
Q

Yeast and fermentation

A

Various ambient yeast strains (bloom & winery)
- complex flavours
- cannot control type & amount
- variation between batches

Cultured yeast (S. cerevisiae)
- consistently perform & produce attractive flavours
- limits the potential complexity

42
Q

Why is temperatur control important in fermentation?

A
  • too hot –> yeast is killed
  • influence the flavours being made
    –> low: volatile aromas, floral character, fruity flavours
    –> high: necessary for extraction of colour & tannin
43
Q

how to remove excessive heat from fermentation

A
  1. heating/refrigeration system
  2. pumping over
44
Q

MLF
(what, gives, start, stop)

A

Malolactic Fermentation/Conversion
- usually after fermentation
- by lactic acid bacteria

HO₂CCH₂CH(OH)CO₂H –> CH3CH(OH)CO₂H + CO₂

  • tart malic acid –> softer lactic acid
  • softens & reduces acid
  • buttery flavours, CO₂

How to start
- raising temperature or not add SO₂

How to avoid
- cool temperatures
- add SO₂
- filtering out the bacteria

45
Q

Pre-bottling maturation & blending (3)

A
  1. Lees
  2. Pre-bottling Maturation
  3. Blending
46
Q

Lees
(2 types, def/removed)

A
  1. gross lees: suspended particles (yeast cells & grape fragments) heavy enough to fall to the bottom of the fermentation/storage vessel within hours.
    Can form unpleasant aromas if not removed
  2. fine lees: smaller particles.
    May settle more slowly –> removed gradually through the wine maturation process (see sedimentation).
    Some wm keep a white wine in contact with fine lees during pre-bottling maturation –> extra flavours, richer texture
47
Q

Pre-bottling Maturation
(to do or not to do)

A

NO
- retain primary fruit aromas –> bottled after a few months in inert vessel
- inexpensive red & white (California White Zinfandel), and some premium (Australian Rsl)

YES
- maturation vessel: add oak flavour or allow oxidation
- over time components in the wine react with each other
–> alter the flavour or balance
–> formation of particles & sediment

48
Q

what does a wine need to be able to age

A

sufficient level of
- tannin
- acid and/or
- alcohol
and
flavour that will develop in an interesting way

49
Q

Blending - what & when?

A
  • both sv and different varieties
  • at any stage during the wm process
    (mainly after fermentation or during maturation)
  • different grape varieties, vineyard location, vintages, wm processes used (parts w/wo MLF, barrel etc.)
    (constraints by local wm regulations)
50
Q

3 reasons for blending

A
  1. Balance
    enhancing quality
    i.e. freerun juice with press wine to incr. tannins
  2. Consistency
    different barrels/vats, vineyards, harvesting times, slight inconsistencies that arise during wm
  3. Style
    house style
    vintage variations (weather)
51
Q

Clarification
(3 main techniques)

A
  1. Sedimentation
  2. Fining
  3. Filtration
52
Q

Sedimentation

(Clarification)

A
  • most wine will undergo sedimentation after fermentation
  • gross lees settles in a deposit
    –> slowly & gently pump wine into a different vessel (racking)
  • fine lees continue to form deposit –> repeated rackings
  • relies on gravity, but can be accelerated by centrifuge (generally very expensive equipment)
53
Q

racking

A

pumping a wine over in a new vessel, leaving the deposit behind

54
Q

Fining
(what, how)

(Clarification)

A
  • speeds up the process of constituents clumping toghether, so they can be removed before bottling
  • adding a fining agent, a substance that forms bonds with certain wine constituents, remove particles by filtering
  • widely practised, generally considered an important step in ensuring wine stability
  • stabilisation process
  • some choose not to
55
Q

Filtration

(Clarification)

A
  • a process that physically removes particles from a wine as it is passed through a filter
  • after fermentation, during maturation, before bottling
  • gross and fine lees

2 methods:
1. Depth filtration
Thick layer of material, solid parts get trapped inside
Able to handle very cloudy wines.
Can be used to remove gross lees.
2. Surface filtration:
Resemble very fine sieves.
Solic particles trapped on surface.
Very expensive and clog up extremely easily.
Generally used after depth filter.
Sterile filtration: small pore size, remove yeast & bacteria

  • Some bottled unfiltered.
56
Q

Depth filtration

(Clarification)

A
  • Thick layer of material, solid parts get trapped inside
  • Able to handle very cloudy wines.
  • Can be used to remove gross lees.
57
Q

Surface filtration

(Clarification)

A
  • Resemble very fine sieves.
  • Solic particles trapped on surface.
  • Very expensive and clog up extremely easily.
  • Generally used after depth filter.
  • Sterile filtration: small pore size, remove yeast & bacteria
58
Q

When is a wine stable?
Ex deposit

A

If it over a specified time frame, changes in a slow, predictable manner.
The time frame and the amount of change deemed to be acceptable will vary from wine to wine.

ex:
High-volume inexpensive red, consumed within a year: should not throw a deposit in the bottle.
Mature Vintage Port: expected to throw a thick deposit over the course of the 50-60 years it may spend in bottle.

59
Q

3(4) important areas that require stabilisation

A
  1. Tartrate Stability
  2. Microbiological Stability
  3. Oxygen Stability

(4. Deposit/clarity –> Fining)

60
Q

Tartrate Stability and tartrates
(what, how)

(Stabilisation)

A
  • Tartaric acid is less soluble in wine than in grape juice
  • Over time it can form crystals called tartrates
  • Clear/ purple crystals
  • harmless & flavourless
  • cool temperature accelerate formation
    –> long maturation in cool cellar
    –> chilling <0C a short period –> filter
  • some choose not to
61
Q

Microbiological Stability
(what, how, different wines reg. risk)

(Stabilisation)

A
  • yeast and bacteria can spoil a wine
  • keep winery equipment clean

only wines not at risk: fortified
(toxic alcohol level for microorganisms)

Naturally quite resistant to microbiological spoilage:
dry, high acid, MLF - high alc, acidity and lack of nutritients

At risk from yeast or bacterial spoilage:
Wines that have not undergone MLF, or have low/medium alcohol, low acidity, a little residual sugar
- careful handling
- SO2
- sterile filtration

62
Q

Oxygen Stability
(what, how)

(Stabilisation)

A
  • excessive levels of oxygen dissolved or if it can enter through packaging
    –> the wine will oxidise (lose fresh fruit flavour, turn brown)
  • avoid exposure to oxygen
  • keep SO2-levels topped up

Precautions during packaging to ensure that oxygen does not come into contact with the wine:
- bottles can be flushed with CO2 or N2 before filling

63
Q

Parts of packaging

A
  1. Bottles and Alternatives
  2. Closures
64
Q

Bottles & alternatives
(3 types, +&-)

A
  • glassbottles
    (+) Portable, cheap to produce, quite strong, do not allow air in, do not taint flavours
    (-) Heavy & rigid, transport costs, space
    –> Light weight, transport in bulk
    –> Vulnerable to oxidation after opening (space for air)
  • plastic bottles
    (+) Lighter
    (-) Small amount of air pass through
    (can lose freshness & fruitiness over a period of months)
  • BiB
    (+) Bag collapses as wine is consumed –> prevent air from entering
65
Q

Closures
(must …, factors, 3 types)

A
  • protect the wine until it is consumed
  • type chosen based on:
    consumer factors (ease of use)
    practical fact. (which closure a bottling line is designed to use)
    bottle maturation (–> amount of oxygen they allow)
  1. Cork
    Original, and still most widely used
    Allows a small amount of oxygen to gradually enter the bottle
    (-) Some with cork taint (TCA) - mouldy, cardboard
    (-) Some allows too much oxygen in (incr with age)
  2. Synthetic corks
    Generally some form of plastic
    Used to be suitable for wines consumed within a year, now premium versions that allow longer storage
  3. Screw caps
    Championed by producers from Australia and New Zealand
    Do not taint the wine
    Can provide impermeable seal, preserve fruit flavour
    Some sc now permit some oxygen transfer
66
Q

Post-bottling maturation

  1. … of wines best consumed within… ageing results in …
  2. … wines can mature in bottle for… and are not at their best …
  3. Ex that mature
  4. Ideal storage
A
  1. majority of wines are best consumed within a year of bottling (ageing results in loss of fresh primary fruit flavours)
  2. many wines can mature in bottle for several years and are not at their best in the years immediately after bottling
  3. Ex: Vintage Port, German Rsl, cru classés Bx
  4. Store
    - undisturbed
    - cool, constant temperature (10-15C)
    - dark
    - constant humidity
    - lying on their side (cork–> moist)
67
Q

Constituents of wine

A
  • water
  • ethanol
  • sugars
  • acids
  • tannins & colour
  • aroma & flavour compounds

WSET 3 (45 decks)

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