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WSET 4 > Vinification > Flashcards

Vinification Flashcards

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1
Q

Name wine components

A 
\Water
Alcohol
Acids
Wine aromatics
Residual sugar
Glycerol
Phenolics
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2
Q

Alcohol formed during fermentation

A

Ethanol

Gives sense of sweetness and bitterness
Contributes to the fullness of the body

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3
Q

Principal acids in wine

A

Tartaric acid and malic acid (come from the grape)

Lactic acid and acetic acid (produced acids)

Contribute on balance of sugar and fruit concentration

High acidity wines appear leaner on palate

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4
Q

Acetic acid expression

A

Volatile acidity

Vinegar smell

Generally in small concentration, if high it is fault

Reacts with alcohol and form ethyl actate (nail varnish remover smell)

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5
Q

Acidity and pH

Measuring acidity and pH

A

Linked but not correlated

high acidity usully means low pH and vice versa

grams per litre (g/l) in tartaric acid. Typical range of 5.5-8.5 g/l

pH range typically 3-4. Inverse scale, lower the number the more concentrated the acidity. And logaritmic (pH of 3 is ten times more acidic than pH of 4)

Low pH increases microbial stability of wine and effectiveness of SO2, gives red wine bright colour and enhances ability to age

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6
Q

Wine aromatics kinds

A

From the grapes

Created by fermentation due to presence of aroma precursors in grape must

Originating from fermentation and its by-products

Aromas from other sources

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7
Q

Aromas from grapes

A

Methoxyparazines (grassy, green pepper aromas in Sauvignon Blanc)

Rotundone (Pepper aroma in Syrah)

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8
Q

Aromas from fermentation (based on presence of aroma precursors)

A

Thiols (box tree aroma of Sauvignon Blanc)

Terpenes (linalool and geraniol - grapey aromas in Muscat)

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9
Q

Aromas from fermentation and its by-products

A

Esters (formed by reaction of acids and alcohol)
Fresh and fruity aroma essential for young wines
Isoamyl acetate (banana - Beaujolais Nouveau)
Unstable and will breakdown few months after
fermentation

Acetaldehyde (due to oxidation of ethanol)
Masks fruit aromas
Distictive smell of Fino sherry

Diacetyl (during fementation, especially malolactic)
Buttery aromas

Aroma of reductive sulfur from yeast during fementation and lees ageing (stuck match up to rotten egg)

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10
Q

Aromas from other sources

A

Vanilin

Eucalyptol

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11
Q

Residual sugar classification levels (EU)

A

Residual sugar contributes on body

Dry/sec/trocken
up to 4 g/l
not exceeding 9 g/l provided acidity is not more than
2g below RS content
(wine with 9 g/l RS can be SEC if it has 7g total acidity)

Medium dry/Demi-sec/Halbtrocken
more than 4 g/l no more than 12 g/l
up to 18 g/l provided acidity is not more than 10 g
below RS content

Medium or medium sweet/Moelleux/Lieblich
more than 12 g/l not exceeding 45 g/l

Sweet/Doux/Suss
at lease 45 g/l

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12
Q

Glycerol

A

Derived from sugar in grapes

In higher level in wines from botrytis and carbonic maceration

Contributes with smoothness to the texture and perception of fullness of the body.

Slightly sweet body

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13
Q

Phenolics

A

Group of compounds from skins, stems and seeds

Anthocyanins and tannins

Tannins bind with proteins in the mouth giving drying sensation on the palate.

Residual sugar can make tannins to seem softer

High acidity, dry wine - astringent tannins

Tannins react with other compounds during fermentation and maturation and change composition and their final feel

Important for structure and balance of wine

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14
Q

Who identified yeast and bacteria and when?

A

Luis Pasteur iìn the 1860s

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15
Q

Conventional winemaking

A

Temperature control

Use of additives and processing aids of many kinds
adding sugar, use of cultured yeast, fining agents etc

Manipulations (high technology such as reverse osmosis)

Aim is to produce stable wine

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16
Q

Organic winemaking

A

Wine from certified organically grown grapes

Allow many common additives and process from conventional winemaking (adding tannins, cultured yeast etc.)

Certifying body - ECOCERT

EU - allows regulated use of SO2

USA - excludes any SO2 use and require naturally occuring SO2 to be bellow 10 mg/l
(another category in USA - “wine made from organic grapes” allow SO2)

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17
Q

Biodynamic winemaking

A

DEMETER certifying body

wine from certified biodynamic grown grapes

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18
Q

Natural winemaking

A

Rejects many modern interventions in favour of artisan practises from the past.

Nothing added nothing removed

Fewest possible manipulations, fermentation by ambient yeast, absolte minimum of SO2 added

No certifying body

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19
Q

Reductive (protective) winemaking

A

Minimising contact with oxigen

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20
Q

Ullage

A

Headspace between wine and top of the container

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21
Q

2 important gases in winemaking

A

Oxygen and sulfur dioxide

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22
Q

Effect of oxygen in must and wine

A

Timing and amount of oxygen is the key

Phenolic compounds in red wine have anti-oxidative effect therefore red wine is more resistant

Advantages:
Oxygen is needed in the beginning of fermentation to
promote yeast growth and prevent reductive off
flavours

Increases oxidative stability of wine (increased ageing 
potential)

In red wine, essential in reaction between 
anthocyanins and tannins to lead to greater colour 
stability

Disadvantages:
Threatening for production of fruity wines

Oxidative reactions such as forming acetyldehyde 
gives nutty, apple aroma

Can favour growth of spoilage microbes such as 
acetic acid bacteria and Brettanomyces
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23
Q

Exposure to oxygen can be limited by

A

Avoiding ullage in vessels

Use of inert gases (nitrogen, carbon dioxide, argon)

Addition of sulfur dioxide

Use of impermeable containers (steel, concrete)

Cool, constant temperatures

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24
Q

Exposure to oxygen can be increased by:

A

Use of cap management techniques

Use of small wooden barrels

Increasing the number of racklings or lees stirring

Allowing ullage

Hyperoxydation (must) or micro-oxygenation (wine)

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25
Q

Sulfur Dioxide in winemaking

A

Preservative
Anti-oxydant
Anti-microbial - protects from yeast and bacteria

Forms - gas (sulfur dioxide), liquid (potassium
metabisulfite) or solid (potassium bisulfite)

10 mg/l naturally created by fermentation (more than this the label has to state that the wine contains sulfites)
EU max. permitted 160 mg/l for red wines
210 mg/l for white wines

Bound SO2 - SO2 which reacts with compounds in wine
or must, Ineffective against oxidation
Free SO2 - molecular form effective against oxidation

Greater amount of SO2 has to be added to wines with high pH

High levels of SO2 can dull wine aroma and flavours, eventually make the wine taste harsh

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26
Q

Transportation to the winery

A

In small crates - minimal crushing, limited oxidation
Large crates - some crushing (oxidation) adding SO2

Minimising oxidation and microbial spoilage:
    Harvesting at night or sunrise
    Addition of SO2
    Cold storage
    Sanitizing harvesting equipment
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27
Q

Grape reception

A

Sorting on conveyor belt or srew conveyor

Chilling
    Preserving fruit aroma, reducing microbial spoilage
    Slows down processing (higher cost)
    Possibility of heat exchanger
    Cost of energy and equipment

Sorting (triage)
Better the sorting, higher the cost
Labour requirement, lowering yield
Sometimes MOG only (material other than grapes)
Quality wine sorting:
Removing unwanted grapes before picking or
during hand harvesting
Sorting by hand before and/or after destemming
Optical sorting (expensive equipment)

Destemming
If stems are not ripe, they can convey green flavours
and bitter tannins into wine
Grapes not destemmed for:
Red wine fermentation with whole bunches
(Burgundy Pinot Noir)
Carbonic maceration (Gamay in Beaujolais)
Whole bunch pressing for some white wines
(common for high quality sparkling wine)

Crushing
Gentle enough not to break seeds
Combined crusher-destemmer machimes
Grapes turn into must

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28
Q

Must

A

Mixture of grape juice, pulp, skins and seeds

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29
Q

Pressing options

A

Pneumatic press (“air bag press”)
Cylindrical cage with bladder that inflates
Can be programmed to different pressures
Can be flushed with inert gas

Basket press (“vertical or champagne press”)
Pressure applied from above, juice runs through holes
on the sides of press, collected by tray on the bottom
Not sealed vessel, cannot be flushed with inert gas
Holds small loads
Labour intensive

Horizontal screw press
Mounted horizontally, above rectangular draining tray
Less gentle
Requires batch processing

Continuous press
Allows grapes to be continuously loaded
Less gentle

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30
Q

Pomace

A

Solid remains of grapes left after pressing

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31
Q

Must adjustments

A

Generally after must clarification for white wines

Enrichment
Usually before or during fermentation to raise alcohol
Adding dry sugar, grape must, grape concentrate or
rectified concentrated grape must (RCGM)
OR concentration process - reverse osmosis, vacuum
evaporation, cryoextraction (least expensive)
EU is split into zone to indicate permited enrichment

Reducing alcohol
Adding water
Only allowed in some regions
! also dillutes aroma, flavours, acids

Acidification
also used to lower pH
Usually addition of tartaric acid
Citric acid (not permitted in EU)
Malic acid and lactic acid (used after malo)
Before, during or after fermentation
EU split into zones to indicate permitted acidification
EU do not permit to both acidify and chaptalize

Deacidification
Adding calcium carbonate (chalk) or potassium
carbonate
Or using Ion exchange (expensive investment)

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32
Q

Chaptalization

A

after Jean-Antoine Chaptal

Adding dry sugar in form of beet or cane sugar

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33
Q

Cryoextraction

A

Freezing must (or even the final wine) and removing ice from it

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34
Q

Enrichment

A

Usually before or during fermentation to raise alcohol

Adding dry sugar, grape must, grape concentrate or rectified concentrated grape must (RCGM)

OR: concentration process - reverse osmosis, vacuum
evaporation, cryoextraction (least expensive)

EU is split into zone to indicate permited enrichment

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35
Q

Reducing alcohol

A

Adding water

Only allowed in some regions

! also dillutes aroma, flavours, acids

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36
Q

Acidification

A

Also used to lower pH

Usually addition of tartaric acid
Citric acid (not permitted in EU)
Malic acid and lactic acid (used after malo)

Before, during or after fermentation

EU split into zones to indicate permitted acidification
EU do not permit to both acidify and chaptalize

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37
Q

Deacidification

A

Adding calcium carbonate (chalk) or potassium carbonate

Or using Ion exchange (expensive investment)

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38
Q

Alcoholic fermentation definition

A

Conversion of sugar into ethanol and carbon dioxide carried by yeast in the absence of oxygen (anaerobically)

Also produces heat

39
Q

Yeast

Needs and what they produce

A

Group of microscopic fungi that convert sugar into alcohol

Initially they need oxygen to multiply quickly, but once oxygen is used they switch to fermentation

They need: right temperatures, nutrients (nitrogen),
absence of oxygen

Fermentation produces:
    Alcohol
    Carbon dioxide
    Heat
    Volatile acidity
    Small amount of SO2
    Wine aromatics (from aroma precursors)
    Glycerol - increasing body of wine

Most common species of yeast is:
Saccharomyces cerevisiae
Can stand high acidity and alcohol, resistant to SO2

40
Q

Thiols

A

Aroma precursor

Gooseberry aroma in Sauvignon blanc

41
Q

Terpenes

A

Aroma precursor

Linalool and geraniol - floral grapey aroma in Muscat

42
Q

Esters

A

Aroma precursor

Banana flavours in Beaujolais Nouveau

43
Q

Most common species of yeast

A

Saccharomyces cerevisiae

Can stand high acidity and alcohol, resistant to SO2

44
Q

Ambient yeast

A

Present in the vineyard and winery

Range of species of yeast (Kloeckera, Candida) out of which most will die when alcohol reaches 5%. Saccharomyces cerevisiae will quickly become dominant

Advantages:
Add complexity by producing different aromas
No additional cost
Unique to place of origin - supporting terroir
Can be used as part of marketing

Disadvantages:
Fermentation may start slowly (danger of build up of
volatile acidity and spoilage yeast - such as Brett)
Fermentation to dryness can take more time
Increased risk of stuck fermentation
Consistent product cannot be guaranteed

45
Q

Cultured yeast

A

Also selected or commertial yeast

Low levels of nitrogen can lead to stuck fementation and rotten egg smell from sulfur compounds

Selected in laboratory, usually single strains of Saccharomyces cerevisiae

Must has to be chilled (to surpress ambient yeast) or SO2 must be added to let cultured yeast to multiply. Started batch with cultured yeast is added to must to be fermented.

Advantages
    Reliable fast, fermenting to dryness
    Low levels of volatile acidity
    Less risk of spoilage
    Consistent product
    Large selection available - can affect the style of wine

Disadvantages
Leads to certain similarity
Adds cost

46
Q

Yeast nutrients

A

Nitrogen (prevents stuck fermentation and rotten egg smell)

Diammonium phosphate (DAP)

Thiamine (vitamin B1)

47
Q

Fermentation temperatures

A

Cool 12-16 Fresher fruitier whites or rose

Mid range 17-25 Easy drinking fruity reds with low tannin
less fruity whites
Warm 26-32 Powerful red wines

Above 35 fermentation may slow down and stop

48
Q

Options for temperature control

A

Temperature of the cellar

Water or glycerol jackets that surround vessels

Inserts put into vessels

Reducing temperature by pumping over which releases heat

49
Q

Fermentation vessels

A 
Stainless steel
    Easy to clean
    Range of sizes
    High degree of control over temperature
    Protection from oxygen
    High level of mechanization
    Initial investment

Concrete
Inexpensive
Maintain even temperature more efficiently
Eggs - expensive
set up currents which mix lees during maturation

Wood
    Retain heat well
    Attention to hygiene has to be paid
    Bacteria and spoilage organisms risk
    Small amount of oxygen 
    Expensive when new oak is used

Alternatives
Plastic (permeable to oxygen, difficult to control temp)
Terracotta

50
Q

Malolactic conversion

A

Result of lactic acid bacteria converting malic acid into lactic acid and carbon dioxide and it produces heat.

During and after alcoholic fermentation

Encouraging conditions:
18-22 degrees
moderate pH (3.3-3.5)
low total SO2

Historically naturally started in spring when cellar warmed up, now lactic acid bacteria is added

Avoiding it: adding enzyeme lysozyme (kills lactic acid bacteria) or filtering, keeping temperature below 15

Routine for red wine, choic for white wine

Outcomes:
    Redustion in acidity and raise in pH
    Colour loss in red wine
    Greater microbial stability (prevents malo 
      spontaineously happening later)
    Modification of flavour (slight loss of fruit, adding 
                butterly notes)
    Increasing volatile acidity
51
Q

Alcohol adjustment techniques

A

Acidity and pH can be adjusted

Removal of alcohol
Adding water to must (if permitted)
Reverse osmosis - form of cross flow filtration which
removed flavourless permeate of alcohol and
water, which can be destilled to remove
alcohol. Permeate is then blended back to
recreate the wine.
Spinning cone - First extracts volatile aroma compounds
and then removes alcohol. Flavour components
are then blended back into wine

52
Q

Maturation for young fresh wine

A 
Young aromatic fruity
    Protecting from oxygen
    Blanketing with so2 or inert gas
    Stainless steel
    Can be stored in bulk and bottled for final customer
53
Q

O

Effect of oxygen in maturation

A

Reduction in primary aromas, development of tertiary

Influencing colour of wine
Exposing young red to oxygen stabilizes colour
Anthocyanins bind with tannins

Softening tannins

54
Q

Wooden vessels and oxygen

A

Most exposure when doing transfers, rackling, lees stirring or topping up - when bung is removed

Some wine is lost because it impregnate the wood and alcohol evaporates - gradual concentration of the wine

Small vessels have large surface to volume ratio which encreases ageing, barrels need to be frequiently topped up (more exposure to oxygen)

55
Q

Microoxygenation

A

Cheaper alternative without wood

Bubbling oxygen through wine

Increases colour stability and intensity, softens tannins, improve texture and reduce the presence of any unripe herbaceous flavours

More quick, cheaper and can be controlled

Oxygen in wine can provide environment for spoilage microbes such as acetic acid bacteria or Brettanomyces

56
Q

Temperatures for maturation of white and red wine

A

White - 6-12

Red - 12-16

57
Q

Effect of wood on wine

A

Age of the vessel
New wood contains various extractable compounds
Barrel looses about 50% of it new oak flavours during
the first year
New wood is used usually as proportion of blend

Size of the vessel
Greater extraction from wood and exposure to oxygen
in small vessels

Type of wood
European (French, Hungarian, Russian, Slavonian)
Imparts more tannin
More expensive production (must be split in staves)
American
Higher levels of lactones (cocounut aroma)
Greater aroma impart than European oak
Can be sawn, grows faster

Tightness of grain
Oak from continental climates grows slower and the
grain is tighter (slower extraction of compounds)

58
Q

Production of barrels

A

Wood seasoning
Outside for 2-3 years.
Lowers humidity levels in wood, increases flavour
Cedar aromas

Heating staves to bend in shape
Transforms tannins and aroma compounds

Toasting
Light / medium / heavy toasted
Aromas: spice, caramel, roasted nuts, char and smoke

59
Q

Price of barrel ageing and its alternatives

A

Barrels are expensive to buy

Minitoring costs

Performing winemaking operations such as lees ageing is labour intensive with growing number of barrels

Cleaning and sanitation (avoiding spoilage microbes such as Brett)

Maturation is slow process adding on cost, return on investment is slow

Alternatives:
Oak chips or staves
quick to have effect
can be speeded up by micro-oxygenation

60
Q

Define lees

A

The sediment which settles on the bottom of the wine vessel (dead and dying yeast and bacteria, grape fragments, precipitated tannins, nutrients and other compounds)

Gross lees (settled in 24h) and fine lees

May be removed by racking

61
Q

The role of lees in maturation

A

Yeast autolysis releases compounds contributing to flavours, body and texture.

Some of these compounds bind with phenolic compounds in grapes, reducing colour and softening tannins.

Also bind with wood components such as wood tannins (reducing astringency and modifying flavours from wood)

White wine - yoghurt, dough-like, biscuit, toast aromas

Helps with stabilization against unstable proteins (prevents hazes)

Protect from oxygen, helping to maintain slow, controlled oxidation during maturation and reducing need for SO2.

But if layer of lees is too thick, it can produce volatile reductive sulphur compounds.

Lees provide nutrients for microbes so can help to grow lactic acid bacteria for malolactic fementaion (but also risk of Brett)

Raised labour cost from monitoring and storing

62
Q

Yeast autolysis

A

Dying and breaking down of yeast

63
Q

Racking

A

Process of transfering wine from one vessel to another with aim of removing sediment

Can be oxidative process

64
Q

Blending

What is blended and what are the reasons?

A

Can happen at any stage but most common before finishing

Combining:
   Different grape varieties
   Different locations
   Different grape growers or sellers
   Different vintages
   Wine which has been treated differently
   Wine which has been treated equally for logistical 
   reasons

Reasons:
Balance - adjusting certain characteristics for balance
Consistency - non vintage sparkling wine, cheap wine
Style - ccertain house style, quality levels
Complexity - greater range of flavours
Minimise faults - diluting faulty batches
Volume - bought grapes, different parcels
Price - cheaper varieties

Best carried before stabilization

65
Q

Post fermentation clarification options

A

Sedimentaton

Centrifugation

Fining

Filtration

66
Q

Sedimentation

A

Natural clarification option

Forming sediment on the bottom of the vessel which will be racked off

The larger the vessel the greater the number of rackings needed

Sedimentation avoids the loss of texture and flavour

Long process, suitable for premium wines.

If barrel maturation takes place sedimentation is part of the ageing process

67
Q

Centrifugation

A

Rapid spins to clarify wine.

Can replace depth filtration and allow early bottling

Only for high volume wineries

68
Q

Fining

A

Fining agent is added to speed up the process of precipitation of suspended material in wine. The fining agent and the colloid attract each other and form a solid large enough to be removed by racking or filtration

Clarifies the wine and helps to stabilize it.

Can remove positive compounds or make the wine unstable if too much is added (over-fining)

Each fining agent has particular properties which can offer solution to problems

Protein or mineral origin

1) Agents that remove unstable proteins
Betonite - form of clay, some colour loss in red wines
Mainly used for whites (avoiding hazes)
Protein in reds binds with tannins (clear wine)

2) Agents that remove phenolics (colour and bitterness)
Egg white - fresh or powdered form
able to remove harsh tannins and clarify
Gentle, but must be declared on label
Gelatin - Removes bitterness and astringency in red
and browning in white
easy to overfine (stripping flavours)
Casein - Removes browing from whites and clarifies
to some extent. Must be declared on label
Isinglass - very effective for whites (bright appearance)
Too much - hazes and fish smell (from fish bladders)
Vegetable protein products - from potato or legumes
PVPP - insoluble plastic in powder form
Removes browning and astringency from
oxidised white. Rarely used for reds

3) Agents that remove colour and off-odours
Charcoal - removes brown colours (Pale Cream
Sherry) and some off-flavours
Overfines easily - stripping flavour

69
Q

Filtration definition

A

Separation technique used to eliminate solids from suspension by passing it through a filter or medium consisting of porous layers taht trap solid particles, thus making the liquid clear.

The most common form of clarifying wine

70
Q

Depth filtration

A

Traps particles in the depth of the material that forms the filter.

It can cope with fluid with many particles in it

Does not block easily, however is not absolutely reliable

Not absolute filter

Diatomaceous earth (DE or Kieselguhr) pure silica, inert
Rotary vacuum filters use it for very cloudy wine
Oxidative process
Enclosed DE filters can be flushed with inert gas
DE comes in range of particle sizes
Must be disposed responsibly (additional cost)

Sheet Filters (plate, frame, pad filters)
The more sheets, the quicker the filter
Require initial investment

71
Q

Stabilization

A

Includes tackling the potential for unwanted hazes, deposits in the bottle and rapid chanes in wine (browning).

Protein stability
Fining with betonite
Tartare stability (potassium and calcium bitartrate)
-4 degrees crystals form, then filtered
only removes potassium bitartrate
cost of cooling and equipment
Contact process
Quicker, more reliable, cheaper
Wine cooled to 0 degrees, Potassium bitartrate is
added to form cryslals and after 2h filtered
Electrodialysis
Charged membrane to remove selected ions
High initial investment, low operation cost
Both potassium and calcium ions
Ion exchange
Does not remove tartrates but replaces potassium
and calcium ions with hydrogen or sodium ions
It is not allowed in some territories
Carboxymethylcellusose (CMS)
Cellulose extracted from wood and prevents
tartrates to develop to visible size
Cheap and used on white or rose
Not suitable for red as it reacts with tannin (hazing)
Metatartaric acid
Prevents growth of crystals
The acid is unstable and effect is lost over time
Microbiological stability
Residual sugar - risk of refermenting.
Removing yeast through sterile filtration or adding
sorbic acid or SO2
Malolactic in the bottle (filtration or making sure malo
was completed before)
Infection with Brett (treatment with DMCD dimethyl
dicarbonate - Velcorin)

72
Q

Tartare stabilization options

A

Tartare stability (potassium and calcium bitartrate)
-4 degrees crystals form, then filtered
only removes potassium bitartrate
cost of cooling and equipment
Contact process
Quicker, more reliable, cheaper
Wine cooled to 0 degrees, Potassium bitartrate is
added to form cryslals and after 2h filtered
Electrodialysis
Charged membrane to remove selected ions
High initial investment, low operation cost
Both potassium and calcium ions
Ion exchange
Does not remove tartrates but replaces potassium
and calcium ions with hydrogen or sodium ions
It is not allowed in some territories
Carboxymethylcellusose (CMS)
Cellulose extracted from wood and prevents
tartrates to develop to visible size
Cheap and used on white or rose
Not suitable for red as it reacts with tannin (hazing)
Metatartaric acid
Prevents growth of crystals
The acid is unstable and effect is lost over time

73
Q

Microbiplogical stability options

A

Residual sugar - risk of refermenting.
Removing yeast through sterile filtration or adding
sorbic acid or SO2

Malolactic in the bottle (filtration or making sure malo
was completed before)

Infection with Brett (treatment with DMCD dimethyl
dicarbonate - Velcorin)

74
Q

Surface filtration

A

Surface filtration
Stops particles that are bigger than the pore size of
the filter. Absolute filter
Membrane filters (cartrige)
Slower, wine must be pre-filtered (easy to block)
Sterile filtering
Initial invetment is small, cartriges are expensive
Cross-flow filters (tangential)
Wine passes through filter while cleaning the
surface of the filter as it goes
Expensive machine, but no cartridges or sheets

75
Q

Finishing options

A

Final full chemical analysis (at least alcohol, residual sugar and free SO2) right before bottling levels of dissolved oxygen and CO2 will be checked.

Adjusting levels of SO2
   lower pH wine requires lower SO2 levels
   Generally 
       white 25-45 mg/l
       red 30-55 mg/l
       sweet 30-60 mg/l

Reducing dissolved oxygen
can accelerate ageing
Sparging - flushing wine with inert gas to remove O2

Adding carbon dioxide
    Added freshness (especially inexpensive white)
76
Q

Sparging

A

Flushing wine with inert gas to remove oxygen

77
Q

Cloudiness and hazes

A

Growth of yeast or bacteria

Failure to filter adequately (or filtereing too fast)

Wrong type of fining agent or over-fining

Remedy:
   Better hygiene
   Pre-bottling analysis
   Slow filtering
   Analysis after fining
78
Q

Wine faults

A

Cloudiness and hazes

Tartrates

Re-fermenting in bottle

Cork taint

Oxidation

Volatile axidity

Reduction

Light strike

Brettanomyces

79
Q

Volatile acidity

A

All wines have volatile acidity but high concentration results n smell of nail varnish or vinegar

Activity of acetic acid bacteria, inadequate levels of SO2 and excess exposure to oxygen

Remedy:
    Sorting fruit to exclude damaged grapes
    Hygiene in winery
    Keeping vessels topped up 
    Careful racking
    Maintaining adequate SO2 levels
80
Q

Reduction

A

Sulfur like smell (onion or rotten egg)

Produced by yeast under stress (low nitrogen levels) or near complete oxygen exclusion during ageing in closed vessels especially when lees ageing

Remedy:
Assuring yeast have enough nutrients and oxygen
Not overloading with SO2

81
Q

Light strike

A

Caused by UV radiation reacting with compounds in wine forming volatile sulfur compounds

Odour such as dirty drain

Wines which are left in direct sunlight or near fluorescent lightning are most in danger

82
Q

Brettanomyces

A

Animal, spicy, famyard smell (complexity in low levels, high levels clear fault)

Difficult to eradicate once it occurs. Wood is hosting the organism

Keys to avoid Brett:
Excellent hygiene
Maintaining effective SO2 levels
Keeping pH level low
Keeping period between alcoholic fementation and
malolactic conversion as short as possible

83
Q

Oxygen management when packaging

A

Final amount of oxygen in the container will determine the shelf life and expected development of the wine

Combination of:
    Dissolved oxygen in the wine
    Oxygen in the head space
    Oxygen in the cork or other closure
    Oxygen transmission rate (OTR) of the cork or closure
84
Q

Options for packaging

A

Glass
No taint to wine and inpermeable to oxygen
Near sterile conditions
Inexpensive to manufacture and recyclable
Best option for ageing
High carbon footprint initially (heat for production)
Heavy to transport and fragile
Once open, subject to oxydation
Clear bottles are susceptible to spoilage by light

Plastic
Light, tought, inexpensive, recyclable
Must be lined with barrier to oxygen
Special filling equipment required

Bag-in-box
Carboard box, flexible bag, aluminium foil as barrier
Flexible pour size, range of container sizes
Good protection from oxygen once opened
Low environmental impact and easy to store
Wine must have slightly higher SO2, low dissolved
oxygen, no head space and low carbon dioxide level
Shelf life 6-9 months

Brick
Tetra Pak
Cardbord with plastic layers and aluminium foil
Filling equipment is large investment

Pouch
Similar to bags inside bag-in-boxes

Can
Light weight, robust, easy to open, impermeable to
oxygen and recyclable
Aluminium has to be lined with plastic to avoid being
attacked by the acidity of wine
Large investment for filling equipment

85
Q

Ideal closure for wine has these properties:

A

Protect wine from rapid oxidation

Be inert so that it does not affect the quality of wine

Be easy to remove and re-insert

Cheap, recyclable and free of faults

86
Q

Natural cork

A

Light, flexible, inert, renewable, natural resource

Positive image for consumers

Variable levels of oxygen ingress - wine ages at different rates in the medium to long term

Can house harmful fungi
Can taint wine through the creation of TCA (2,4,6-trichloroanisole) about 3-5% of bottles
Cleaning corks with stream extraction
Recomposed cork particles cleaned and reconstituted
with plastic
Rigorous quality control during production
Introducing barrier between the cork and the wine

87
Q

Technical corks

A

Cork that has been subected to a manufacturing process

Agglomerated cork (granules glued together)

One-plus-one cork
central part is agglomerated cork and sides are
natural cork

Diam cork
Combination of cork and plastic

Available in different ingress rates

88
Q

Synthetic closures

A

Food grade plastic with silicone coating

Difficult to re-insert in bottle

Limited protection from oxygen
Flavour scalping
Plastic absorbs some flavour molecules

89
Q

Screwcap

A

From tin (impermeable to oxygen) or Saran (form of plastic with low permeability to oxygen)

Wines can become reductive after bottling - therefore lower SO2 levels should be used

90
Q

Glass stopper

A

Vinolok (brand name)

Seal is formed by a plastic ring

Special bottles must be used to ensure perfect fit

As expensive as top quality corks

91
Q

Post-bottling maturation

A

Increases cost
Oxygen transmission rate of closure, oxygen in head space of bottle and dossolved oxygen in wine play key role on ageing (small amount of oxygen is beneficial)

Low level of oxygen at bottling can result in volatile reductive sulfur compounds in wine (rotten egg)

Undisrupted, cool, dark place with consistant temperature ideally around 10-15 degrees and constatnt humidity. If sealed with cork bottles should be lying down.

92
Q

HACCP

A

Hazard analysis of critical control points

Identification of hazards, their seriousness and how to prevent them and correct them

93
Q

Tracability

A

Each consignment of wine will be given lot number which appears on bottle. EU requirement

The winery must keep records of its activities at every point of production

94
Q

Transportation of wine

A

Bulk
Flexitank - single use, recyclable, polyethylene bag
that fits into standard container
ISO tank - stainless steel vessel built to ISO standards
which can be reused
Reefers - insulated tanks with temperature control

Advantages of bulk shipping
More environmentally friendly
Cheaper
Less fluctuation of temperature
Reducing loss of fruit and oxidation
Quality control can be analyzed better
Wine can be adjusted at the final market before
bottling
Shelf life is extented (later bottling)

Advantages of shipping bottles
Producer has control over the entire product
Disadvantages of shipping bottles
Smaller amount of wine in one container, higher cost
Weight of glass
Potential damage, breakage, temperature, labels
Shorter shelf life for inexpensive wine (bottled earlier)

WSET 4 (32 decks)

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