Common Elements in Winemaking and Maturation

Question 1

What are the two ends approach on winemaking ?

Answer 1

Control each part of the winemaking process.
- Winemaking is tailored with a particular stylistic goal and techniques are choosen to achieve this goal

Hands-off approach
Overall the wine is produced with as little human intervention as possible, avoiding additions including cultured yeasts and sulfur dioxide, and process taht add or take away from the wine

Question 2

Name the constituent parts of grapes and their role

Answer 2

Seeds and stems
- contain tannins
- Seed contain high levels of bitter oil
- stems only available when hand harvested

Skins
- skin and area just beneath contains high concentration of flavour compound
- signature varietal character
- tannins, and colour compounds (higher in red rapes)

Pulp
- Highest component is water
- second is sugar
- Acids (tartaric and malic)

tannins
- large number of chemical coumpoumds are classed as tannin
- At véraison, they are bitter but lower as the grapes ripen.
- Oak contribue some tannins.

Question 3

What is the role of oxygen throughout winemaking and maturation ?

Answer 3

Gas that react with grape juice and mamy other coponents.
The chemical reactions, referred to as oxidation can be positive or negative

Question 4

Describe the role of oxygen in winemaking

Answer 4

• Oxygen is a threat for wine dominated by primary fruit

How to avoid oxygen contact ?
- Antioxidant such as sulfur dioxide
- Grapes are picked at night when its cooler and the chemical reactions are slower
- Grapes are kept chilled until they reach the winery
- Filling airtight winery equipment with carbon dioxide or nitrogen (known as anaerobic winemaking)

Some may say it makes bland and unintersting styles since oxyen develop complexity, but it’s a question of style.

Question 5

Describe the role of oxygen in maturation

Answer 5

• Wine that were protected from oxygen during winemaking will rarely have any contact during maturation. They are stored in inert airtight tanks or vats that are kept full, of stainless steel or ciment with epoxy resin
• Other can be stored in wooden vessels, so small amounts of oxygen can make it throught the oak to react with wine.This can soften tannins and gives more complexity (primary to tertiary)

Red wines become paler and gain hint of brown, white wines become deeper and gain hint of orange

To much exposure can be damaging for fruit flavour and smell, and said to be oxidised. Bacteria will use oxygen to change the wine into vinegar

Question 6

Which factors contribute to the amount of oxidation in barrel maturation ?

Answer 6

• The size of the barrel : small vessels have greater oxidatate effect than large vessels. Rarely kept in barrique for longer than 2 years
• If the barrel is not completely full. Techcnique used for Oloroso Sherry for example.

Question 7

What is the role of Sulfur Dioxide in winemaking and maturation ?

Answer 7

• Acts as antioxidant and antiseptic
• Used to protect freshly harvested grapes and levels are adjusted throughout the process.
• Upper levels of SO2 are controlled by law
• Can cause allergic reactions, even at low levels.
• Although SO2 is produced naturally in fermentation, it is preferrable to keep it low
• Can make wine seem harsh and lacking in fruit.
• Some wont use SO2 at all.

Question 8

What are the two effect of SO2 ?

Answer 8

Antioxidant effect
- protects grape juice and wine from effects of oxidation
- in doing so, it loses the ability to have protective effet and becomes a “bound”
- Level of So2 therefore need constant monitoring

Antiseptic effect
- SO2 is toxic to many strains of yeast and bacteria
- Yeast involved in alcoholic fermentation is able to tolerate levels of So2 that are toxic to other species.

Question 9

What is the purpose of Oak vessels in winemaking and maturation ?

Answer 9

• Allows small level of oxidation , allowing tertiary aromas to develop
• allow extraction of tannin and** flavours **(vanilla, toast, smoke, cloves)
• Oak tannins give more structure to red and white, increasing the textural complexity
• Hygiene is a challenge, difficult to keep free of yeasts, bacteria, moulds and can taint the wine
• Oak vessels differ in characteristics,different types are used to enhance the complexity of final wine

Question 10

What are the factors to consider when chosing oak barrels ?

Answer 10

• Species and origin of oak
• Size
• Production
• Age

Question 11

Describe species and origin of oak

Answer 11

• Different species of oak have different characteristics
• Same species of oak an show different characteristics depending on where it is grown.
  -Often either European Oak or American oak

European oak has broadly similar characteristics around EU, but some forest, especially in France, are considered the finest.

Question 12

Explain size of oak barrels

Answer 12

Small vessels (barrels) such as
- 225-litre barrique
- 228-litre pièce,
have greater effect because more of the wine is in contact with the surface

larger vessels can reach sizes in excess of 2000 litres

Question 13

Explain the production of oak barrels

Answer 13

The way a barrel is made has a vital influence on how it will affect the wine

Toasting of the barrel : heating the staves so they can be bent into shape
transforms tannins and flavour compounds in the oak, giving notes of toast, smoke and spices

Temperature and lenght of heat exposure (level of toasting), affects the flavours

Question 14

Expain the influence of the age of barrels

Answer 14

Effect of toasting diminishes each time the barrel is used
By the time its on its fourth usage, it imparts little flavour or tannin

Flavours of new oak are not desirable for all wines.

Question 15

What are the Oak Alternatives

Answer 15

• Small plank of oak (staves) or oak chips can be inserted during fermentation or maturation in inert winery vessels
• Impart oak aromas and tannins at a lower price
• oxidative effect of barrel ageing can be replicated by dding small, controlled quantities of oxygen to wine vessel

Premium wines are not normally made using these techniques.

Question 16

Explain Stainless steel vessel

Answer 16

• most modern winery vessels
• Easy to keep clean and made in any shape and size
• incorporate temperature control mechanisms (sleeves on the outise or internal coils through which cold or hot liquit is circulated)

Question 17

Explain concrete vessels

Answer 17

Usually lined with epoxy resin, which is inert and waterproof
Commonly used before stainless steel
Less easy to clean and maintain than stainles steel
Thick concret shells help regulate temperature during fermentation and maturation without the need of temperature control equipment.

Question 18

What are the general steps of grape processing ?

Answer 18

• Grape reception
• Destemming and cruching
• Pressing

Question 19

Explain grape reception

Answer 19

receive their first dose of SO2 as they arrive at winery
grapes for premium wine are checked on sorting table to eliminate unripe or rotten grapes

Question 20

Explain destemming and crushing

Answer 20

Optional process

Destemming
-Machine harvested grapes arrive without stems
- Usually done in a machine that can subsequently crush the grapes

Crushing
- breaks the skins of the grapes and liberates a quanity juice (free run juice)
- should avoid to damage the seed to not relase bitter oils and tannins

Question 21

Explain pressing

Answer 21

Separates the liquid and solid constituents of the grape
White wine: before the start of fermentation
Red wine: typically after fermentation

Seeds should remain undamaged, and moder technique are designed to achieve gentle pressing

Traditionally: wine presses were vertical, using a plate that was raised or lowered by lever. Now automated, and particularly used in Champagne

Pneumatic presses are more recent, and consist of inflatable rubber tupe within a perforated horizontal stainless steel cylinder. Apply presser over a large area. Grapes can be kept in closed tanks

Winemakers can decide to separate the liquid into different pressings, called fractions and treat them individually.

Question 22

The winemaker can separate the liquid into different pressings. What are theses liquids called ?

Answer 22

Fractions

Question 23

When can adjustments can be done to the wine ?

Answer 23

Before, duringg of after fermentation
are subject to regulation in the EU

Question 24

What is another word to refer to grape juice ?

Answer 24

Must

Question 25

How can you adjust sugar and alcohol in wine ?

Answer 25

In cooler climate, they may be insufficient narual sugar to give a satisfacotry level of alcohol

Enrichment
- increasing sugar in the juice by adding Rectified Concentrated Grape Must (RCGM). a colourless, odourless, syrupy liquid,
- Before or during fermentation
- This raise the level of alcohol in the wine because more sugar is available
- Forbidden in many parts of the world and is stricly controlled
- Chaptalisation - When sugar from sources other than grapes is added
- Can give better wine, or produce hard and thin waine because there are not enough flavours for the artificial alcohol level.

Remove water from the juice
- Roncentrate sugars and lead to higher alcohol
- Concentrate everything else such as tannins, acids, flavours, faults
- Reduces the volum of juice and less wine is sold.

Remove alcohol from the wine after fermentation
- modern machinery can do it

Question 26

How can you increase or lessen acid in wine ?

Answer 26

Acidification
- Acid is Increased if it has fallen to far during ripenin
- Addition of tartaric acid in powder form
- in europe, only permitted in warmer regions , common in many warm hot regions of the world

Deacidification
- more common in cooler climate regions
- Excess Acid is neutralised by addition of an alkalin substance

Question 27

What are the elements of Fermentations ?

Answer 27

• Alcoholic fermentation
• yeast
• temperature
• Malolactic Conversion

Question 28

What is the year responsible for the majority of wine fermentation ?

Answer 28

Saccharomyces cerevisiae
due to its tolerane of relatively high levels of alcohol and SO2

Question 29

What is the minimum and maximum temperature for a wine to ferment ?

Answer 29

Begin at 5°
stop over 35°

Question 30

What is alcoholic Fermentation ?

Answer 30

• the conversion of sugar into alcohol and CO2, through the action of yeast
• By-products of this process are heat and flavour compounds
• At the right temperature, fermentation continue naturally until all the sugar has been consumed.

Question 31

What can stop alcoholic fermentation ?

Answer 31

• Yeast run out of nutrients
• temperature reaches over 35°
• High sugar (and alcohol) can stop the year from functionning or even struggle to start
• Killing the yeast by adding S02 or grape spirit
• Removing the yeast by filtration, after halted the fermentation by chilling the wine

Question 32

What are the two ways in which a winemaker can control the fermentation?

Answer 32

• choice of the yeast
• temperature management

Question 33

Explain the role and choice of yeast

Answer 33

Two types of yeast

ambient yeast strains
- found on the skins and in the wineray
- believed to increase the cocmplexity of flavours
- lack control fo the winemaker, leading to variations
- No good for high-volume wine

Cultured yeast strain
- individual strains of saccharomyces cervisiae
- specifically selected for their consistent performance and attractive flavours
- Believed to limit the potential complexity of fthe wine

Question 34

Explain the role of temperature in fermentations

Answer 34

Controlling temperature is also influencing the flavours

Too hot: yeast are killed

Lower temperatures
- avoid loss of most volatile aromas(floral)
- Encourage development of fruity flavours in white wines

Higher temperatures
- Necessary to extract colours and tannin from black grape

Question 35

How can you control the temperature during fermentation?

Answer 35

• Monitoring
• Vats have own heatin/refrigeration system
• Excess het can be released by pumping over

Question 36

Explain malolactic conversion

Answer 36

Malolactic conversation (MLC) also named
Malolactic Fermentation (MLF)

Takes place once the alcoholic fermentation has finished
Is carried out by lactic acid bacteria, which convert the tart malic grape acid into softer lactic acids.

Softens and reduces acidity and create buttery flavours and CO2.

Question 37

How can you encourage or avoid MLC ?

Answer 37

May be encouraged by rising the temperature of the wine and by not adding so2 after fermentation

May be avoided through storage at cool temperature, the use of S02, of by filtering out the bacteria.

Question 38

What are the main constituents of wine

Answer 38

Ethanol
- main alcool in wine
- Smaller quantities of other alcohols are also made during fermentation

Tannins and colour
- particularly in red wines

Water
- Most abundant component in wine

Sugars
- vary depending on the style

Acids
- most impoarts are tartaric, malic and lactic

Aroma and Flavour Coumpounds
- hundred of different compounds have been found
- Very small amount

Question 39

What are the elements of pre-bottling maturation and blending?

Answer 39

Lees
Pre-bottling maturation
blending
balance
consistency
style

Question 40

Explain lees in pre-bottling

Answer 40

Dead years cells and grape fragments can make the wine appear cloudy

the particules are heavy enough to fall tothe bottom of the vessel in hours, and the sediments is called gross lees

It needs to be remove because it cause unpleasant aromas

Some smaller particules are slower to settle and are removed gradually during the process. They are called fine lees.

White wine are sometines kept in contact iwht fine lees to add flavours before bottling

Question 41

Explain pre-bottling maturation

Answer 41

If you want a primary fruity wines, maturation will only take a few months in inert vessels. (inexpensive and pure peremium wines

To survive ageing, wine needs sufficient levels of tannin, acidity and/or alcohol, and flavours that will develop in an interesting way

The maturation vessels affect the flavours by oak and oxidation.
Components react with each other aht alter the balance of the wine
Particules can form and fall to the bottom ofo the vessel, which are removed

Question 42

Explain blending

Answer 42

Vital role in winemaking process, including single variety wine
Can take place at any stage of winemaking process but mainly after fermentation or during maturation

Used to improve balance, attain consistency or achieve a style

Can involves wines from different grape varieties, vineyard loactions or vintages

Need to follow regulations

Question 43

Explain the balance of a wine in blending stage

Answer 43

allow the winemaker to adjust the balance of the wine enhancing its quality
ex. free run wine may be blended with press wine to increase tannins

Question 44

Explain the consistency of the wine in blending stage

Answer 44

Significant varion among bottles of a single product is view as a fault

Blending to attain consistency is a vital process

wines matures in small barrels often develop subtly differnt ways from one barrel to another and need blending ni large vat to smooth ou inconsistencies

Even without oak, a wine can have variations in the fruit (vineyards, harvesting time)

Question 45

Explain the style of wine in blending stage

Answer 45

Important to deceding and maintaining style of a wine
winemaker aim to produce a certain house style even in different vintages

Winemakekr may actively create as many blending option as possible in order to achieve a style by
- separating press fractions
- fermenting or maturing the wine in different vells
- only allowing a proportion to go through malolactif conversion
- Using wines of different grape varities, vineyard plots and vintages

Question 46

What are the different type of clarification methods ?

Answer 46

• Sedimentation
• Fining
• Filtration :Depth or Surface filtration

Question 47

Explain the concept of Clarification

Answer 47

Majority of customers expect a clear wine
can be achieved through sedimentation,fining and filtration

Some do not undergo clarification because winemakers value minimally treated wines

Question 48

Explain Sedimentation

Answer 48

After the fermentation, wine will undergo sedimentation and gross lees will settled into a deposit , with gravity. This could be accelerated with a centrifuge, but very expensive

Racking : Wine is slowly and gently pumped into different vessels, leaving sediments behing

Wine will continue to throw a deposit of fine lees during maturation and can be improved by repeated rackings

for some wine, sedimentation and racking is the only clarification that will take place

Question 49

Explain fining

Answer 49

Depositfs may only appear after a perio of time in bottle
Because wine constituents clump together oover time, becoming large enough to be visible.

Fining is a process that **speeds up this process **so these particles can be removed from the wine before bottling
Adding a fining agent , that will form bonds with constituents, and clumps, so that it can then be filtered.

Widely practised, some winemaker choose to not fine their wine believing it can adversely affect flavours and texture.

Question 50

What is filtration

Answer 50

Physically removes particules from a wine as it is passed through a filter.
Can be filtered after fermentation and during maturation to remove gross lees, or prior to bottling to ensure wine is clear

Depth filtration of surface filtration

Question 51

Explain the two types of filtration

Answer 51

Depth filtration
- filters are made from thick layer of material
- solid parts are trapped inside
- able to hande very cloudy wines
- can be used to remove gross lees

Surface filtration
- Filters resemble very fines sieves (tamis)
- solid particles are trapped on the surface of the filter.
- Very expensive and clog up easily
- Usually used for wines that have already been passed through depth filtration filter
- Some pore sizes are small enough to remove yeart and bacteria, referred to as sterile filtration. Use as a treatment prio to bottling

Some wines are unfiltered, because winemakers believe it can negatively alffec a wines’s texture

Question 52

What requires stabilisation ?

Answer 52

Tartrate Stability
Microbiological stability
Oxygen Stability

fining could be seen as the stabilisation of deposits/clarity

Question 53

What is the general concept of stabilisation

Answer 53

It aims to produce a predictable outcome of wine after bottling

The time frame and amount of change deemed acceptablel will vary from wine to wine

Question 54

Explain Tartrate stability

Answer 54

Tartaric acid is less soluble in wine than in grape juice, an over time forms cystale called tartates.

Appear as clear crystals in white wine or purple crystals in red wine

Harmless and flavourless but spoil the appearance

Cool temperatures accelerate the formation of crytals, and in a long maturation period in cool cellar, wine will deposit tartrates

Winemakers can force the crystals to form prior to bottling by chilling the wine down to belo 0° for a short period of time. Crystals are removed by filtration

Not mandatory.

Question 55

Explain microbiological stability

Answer 55

Yeast and bacteria can spoil a wine, and thrive in grape and wine residues
Importantn to keep winery equipement completely clean

• Fortified wines are not at any risk because the level of alcohol is toxic for all microorganisms
• Dry acid wine that has undergone malolactif conversion is also naturally quite resisent. alcohol acidity and lac of nutrients makes it hard to survive

Some winemaker prefer to take the risk rather than sterile filter their wine.

• Low alcohol, low acidity, no malolactic convertion wine are particularly at risk. They are carefully handled with an appropriate amount of SO2 to protect them at all times. They are sterile filtered prior to packaging

Question 56

Explain oxygen stabilitiy

Answer 56

If excessive level of oxygen is dissolved in wine of enter to packages, in can oxidise.

Can be minimised by avoiding expore and keeping SO2 level topped up

In bottling, bottles can be flushed with either carbon dioxide or nitrogen before filling to eliminate oxygen

Question 57

Describe bottles and packaging options

Answer 57

Glass
- Portable, cheap , strong
- Do not allow air to get into the wine
- Do not taint flavours
- Heavy and rigid, adds weight to transport cost and space
- For environmental reason and cost, you can use lighter glass
- Transport wine in bulk an bottle nearer to the country where its sold
- Once open, wine is vulnerable to oxidation

Plastic bottle
- Lighter
- Allows air through plastic and lose freshess over a period of months

Bag-in box packs
- for large volumes of wine
- bag collapses preventing air from entering
- Some air can enter through wall of the bag
- must be used within 18 months

Glass is better for long-term storage

Question 58

What are the type of closures ?

Answer 58

Cork
Technical corks
Synthetic corks
Screw caps

Question 59

Explain the general concept of closures

Answer 59

Must protect wine from harm and adapt to consumer uses

For wines intented for bottle maturation, closure must allow the winen to mature positively. Different closure vary in the amount of oxygen they allow to enter the bottle

Specifi to the style of wine

The consumer markets have very stron preferrences and that can override the coice of the winemaker

Question 60

Explain Cork closure

Answer 60

• OG closure and widely used
• Best for maturation as it allows small amount of oxygen to enter gradually
• Cork closure can suffer from Cork taint

Cork taint is caused by a chemical called TCA (thrichloroanisole) which is present in some corks
Gives mouldy cardboard like aromas.
Treatments are development to preven formation of TCA

Question 61

Explain technical corks

Answer 61

• Agglomerated cork
• Pieces of cork bound together in a typical cork shape with a form of glue or plastic
• Cheaper and only suitable for wines to be drunk within a couple of years
• Some are made for premium wine. **Made from cork granules that have been subjected to a process to minimise TCA. ** Permit a very slow ingress of oxygen and are suitbale for long-term cellaring

Question 62

Explain synthetic Corks

Answer 62

Made from petrochemical based or plant-based plastic
for early drinking wine or premium versions for longer term storage

Question 63

Explain Screw caps

Answer 63

Championed in Australia andn New Zealand.
Do not taint wine, easily opend and resealed
Vary in oxigen the allow. Some types permit lower odygen ingress than coark.
Some studies shown htat they preserve fruit flavour in the wine longer than cork
Consumer acceptante vary considerably

Question 64

What is Post-bottling maturation ?

Answer 64

Majority of wines are best consume within a year of bottling but some can be mature in bottle for weveral year and not at their best when young

Ex: Vintae port finest German Rieslins, Crus classé Bordeaux

Chemistry is still poorly understood

Ageing should be spent undisturbed in a cool dark place, constant temperature around 10°-15°, constant humidity, and stored lying on their side so the cork reman moist and optimum seal is maintained.