Wine making Flashcards
What is good wine made from?
Good grapes - these can only be grown in suitable weather conditions
What will stop wine from being high quality?
Bad weather conditions
What can spoil a good vintage?
Mistakes
Carelessness
Ineptness
What are the 2 main styles of wine making?
Laissez Faire
Interventionalist
What is Laissez Faire style of wine making?
No intervention (no irrigation, traditional methods, wild yeast fermentation, oak fermentation, no temp control, spontaneous malolactic fermentation)
What is interventionalist style of wine making?
Constant intervention
- irrigation, PC controlled crushing, managed harvest, yeast cultures added, stainless steel fermenting, careful temperature control, controlled malolactic fermentation
How were white grapes formed?
Ancient grapes likely red so mutation = white
What type of grapes is white wine made from?
- its yellow
- Can be made from green or red grapes cleared from their skin and seeds
What is vinification and how does it vary for red and white wine?
Conversion of grape juice to wine
- White is more delicate than red
- Differences at several of the vinification stages
What is crushing in white wine production?
1st stage
- Carried out to make juice accessible but is in contact with skins and seeds - so control of contact required as this affects flavour
- With white grapes there is a gentle crushing = free run
Then remaining pulp is pressed.
When red grapes used, light crushing and straight into press
When is a key decision made about when to destem during white wine production and why?
Crushing
- usually stems left for white grapes (tannin source)
- Stems left on = juices flow more freely and easier to press
What is chaptalisation?
When sugar is added during crushing for white wine and this would increase the alcoholic strength
When are preservatives added during white wine production?
Crushing
- stops oxidation of grape juice.
- Include enzymes which produce SO2 and AST which is a mix of tannins, SO2 and ascorbic acid
What do SO2/AST do to wine?
Too high a concentration can spoil the taste
What type of wines is protection against oxidation important for?
Aromatic white wines
- riesling
- vidal blanc
- gewurztraminer
What types of wine can benefit from the oxidation of the grape juice but what may a negative be?
Non-aromatic -chardonnay -Pinot Grigio - Cayuga However some phenolics (contribute to wine flavour) can be oxidised as well
How can white wine be fined and what effect does this have?
Using PVPP and potassium caseinate to stop astringency in the final wine
What is the cooling stage in white wine production?
2nd stage
Carried out to delay fermentation until after pressing asnd settling
If ambient temperature of must is high, then cool by pumping through must chillers
What is the pressing stage in white wine production?
3rd stage
White grapes are always pressed
Best quality if this is gentle - not breaking pips and stems
What are the 2 types of press used in white wine production?
- Traditionally vertical wooden presses in cylinders with slats for juice
- Modern pneumatic presses used (membrane bladder in slatted cylinder that inflates)
How many times is pressing done in white wine production and why?
Twice
- Must from pressing is added to the free run must
- Must contains juice, stems, skins and seeds
What is settling in white wine production?
4th stage
Juice is drained from the press into settling vats - allow skin, pips, stem settle to the bottom of vat or float so they can be removed
What is racking/raking in white wine production
During settling when the skin, pips and stems settl at the bottom/top of vat allowing them to be removed
Takes 6-12 hrs
What happens to the clean juice after racking during settling?
Transferred into separate vats
Juice can be centrifuged to clarify (excessive process which can strip wine of some desirable components)
If any solids remain they will impart bitterness during fermentation
What is acidification in white wine production?
Prior to fermentation, warm climate must can be acidified if acidity is low
What are the 4 fundamental traits of wine?
Acidity
Alcohol
Sweetness
Tannins
What are acids in wine and why are they important?
Come from the wine grapes, add sourness and tartness.
They preserve wine - bacteria doesn’t like acid
What are the most prevalent types of acid found in wine?
Tartaric
Malic
Citric
Which acid is added in the acidification step of white wine production and what does it do?
Tartaric
Helps fix colour and flavour
Not as astringent as other acids
What does citric acid add to wine?
Helps prevent ferric hazes and add freshness to wine
What does malic acid add to wine?
Seen as harsh and astringent
Why is it more advantageous to do acidification before fermentation?
pH control
retains SO2 effectiveness
What is fermentation in white wine production?
5th stage
- is initiated (if not wild) by the addition of 1-2% cultured yeast to the must.
- Traditionally performed in oak casks (difficult to control temp), modern methods = stainless steel vats with temp control jackets
How long does fermentation of white wine take and at what temperature?
Prolonged fermentation at cool (180C and less) temps ensures complete sugar conversion.
Can either be left in contact with or removed from lees (dead yeast particles) which can add flavour, creaminess and freshness
2-3 weeks
What does sur lie mean on bottles of wine?
Left in contact with lees
Is there natural yeast in wine? If so what does it do?
Yes
Causes fermentation
- some are considered as part of personality of vineyard and give wine personality (terroir)
- Modern method removes natural yeast using SO2/flash pasteurisation
What happens in modern wine once natural yeast is removed?
Cultured yeast is added suitable to fermentation temperature used.
What happens regarding yeast once fermentation is underway and why?
Generous amounts of active yeast added
- no longer any oxidation problems
What are the main sugars in ripe grapes?
glucose
fructose
What are the main sugars in uripe grapes?
Glucose
overripe = fructose
What are the products of wine yeast?
Ethanol
Co2
glycerol
How much glycerol is produced by wine yeast and what does it provide?
2-11g/L
Adds sweetness and fullness to wine
How is the amount of co2 in wine determined?
By fermentation temperature
How do home winemakers degas their wines?
BY agitation or the application of vacuum.
Racking and other processes will generally remove bubbles from commercial wines prior to bottling
How do commercial winemakers measure co2 and why?
They may add more co2 to stop oxidation and bacterial contamination of their product.
What is malolactic fermentation wrt white wine production?
Generally performed as a secondary fermentation to soften astringent acidic flavours and to add complexity - can be natural or artificial.
Converts the harsh malic acid to softer lactic acid using various bacteria- for cold climate wines.
CO2 produced as a by product of this process
What type of white wine is malolactic fermentation prevented?
In white wines from warmer climates which have higher sugars, more fruit flavours and less acid.
Process removes yeast and proteins needed for bacterial action
What might be necessary after malolactic fermentation?
de or re acidification.
Calcium carbonate is added to remove tartaric acid (cooler climates)
Acidex is used to remove malic.
In warmer climates can add natural acids - which can be from stems and oak.
What is maturing in the production of white wine?
Clarification by filtration, filtering or fining with bentonite clay (precipitates, yeasts, proteins and grape skin particles to vat bottom)
This prevents unwanted malolactic ferment or further yeast activity.
Wine gains stability but some clarification methods believed to be aggressive and lead to flavour loss
Can have racking
What is cold clarification in white wine production ?
Performed at 40 C to remove tartaric acid (which crystallizes out) easiest in steel tanks. If in wooden casks need cold cellars. Can be bottled at this point or matured in oak casks
What does cask maturing in new oak do in the production of white wine?
overpowering flavours to subtle wines but adds depth and complexity to others.
older barrels give more moderate flavours
What happens in terms of flavour to cask fermented white wine?
Nutty and roasted flavours as wooden barrels breath and some oxidation in fermentation
What happens in terms of cask matured white wine?
Picks up vanilla flavours and tannins - get more of oak flavours
What flavours does barrel oak aging add to white wine?
Vanilla, spicy, buttery, butterscotch and sometimes smoky flavours - also a source of tannins.
Can be other woods but mostly oak used.
Only for white wines of strong character and constitutions.
Light white wines will not take on wood flavours
What happens to white wine if it is over oaked?
Fruit flavour is lost and smells like a sawmill
What is a modern way of oaking wine without a barrel oak?
oak lined steel tanks
oak chips added to tanks
What is bottling in the production of white wine
Finishing step
Importance of cleanliness. Bacterial activity that may occur when warmer prevented by fine filtering
When can wine be bottled?
Straight from lees after fermentation to retain yeast character and freshness - gives slight spritz
Alternatively inject CO2 at bottling for this effect (similar to forced carbonation in beer keg)
Why can bottled wine not be ‘laid down’ to develop a more mature flavour?
As it still contains yeast and bacteria
When can white wine be drunk
some young
some aged for 10 yrs
What are wine tannins?
Key polyphenol in red wine that makes wine taste ‘dry’. They also add complexity, bitterness and astringency.
Where does the colour in red wine come from?
When black or red grapes used to make red wine come into contact with skins
Can white wine be made from red grapes?
Yes
So long as skins are not used and juice is pressed quickly- Champagne made from blending chardonnay (white grape) and two red grapes (pinot noir and pinot meunier)
How are tannins added to red wine?
From skins, pips and stems
They can be added from the wood of barrels - so are found in white wine matured in casks
What are the pros of removing the stems for red wine production?
They are generally partially or fully removed as too much tannin astringency may be extracted if they’re left attached.
What are the pros of leaving the stems attached for wed wine production?
They help aerate the mass for fermentation (which starts yeast off) and lower the acidity and make pressing easier
Name two types of wines that retain stems?
Beaujolais and Rhone
Name two wines that partially remove the stems
Burgundy
Domaine Dujac - say that it adds herbal note to wines
Name 3 wine regions that remove stems
Bordeaux
California
Australia
What is the first step in the making of red wine?
Removal of stem - if being removed
How is crushing done in the production of red wine?
Traditionally by treading.
Modern methods destem and crush with a mechanical crusher (screws through slatted cylinders). Can be crushed without destemming but usually done to avoid too high a tannin level in finished wine
What is the aim of crushing in red wine?
TO split skins and release juices - wild yeasts generally start fermenting here
How can colour be extracted without loss of tannins during crushing for red wine?
Must heated - only for wines with a limited lifespan
What has must already begun to do after crushing?
Fermentation
What temperatures are used in the first fermentation of red wine?
Cooling is used as high uncontrolled fermentation temperature ‘burnout the fruit flavours.
Temps of 25-300 C are maintained and regular venting of co2 required.
What happens if red wines first fermentation is performed at less than 250 C?
There will be to little body in the wine
What happens if the first fermentation of red wine is performed over 300 C?
The result will be too tannic
How long does the first fermentation of red wine last?
4-10 days
What is maceration in red wine production?
Where the must is left to soak with the grape skins
Does rose undergo a longer or shorter maceration period than red?
Shorter
What is stuck fermentation?
Occurs in both beer and win
- when the yeast becomes inactive before fermentation is complete
What is arrested fermentation in the production of red wine?
When the winemaker intentionally stops the fermentation to leave some sugars present
What can stuck fermentation lead to?
Wine being spoiled by oxidation or bacteria
What are the causes of stuck fermentation?
Extreme temps killing of yeast
Must being low in nitrogen
Overripe grapes
Can fermentation be restarted once it has become stuck?
No
- Dying yeast cells release compounds that inhibit the growth phases of additional yeasts
What do winemakers add to the must to avoid stuck fermentation?
- Temp resistant yeast
- Adding nitrogen compounds
- Altering levels of SO2 to suppress certain bacteria that form a symbiotic relationship with the yeast
All will alter final taste of wine - in particular for grapes with low nitrogen to sugar ratios e.g. Chardonnay/Riesling
What gives body and colour to red wine?
Contact with skins, pips and sometimes stems
What do premium wines need more of and how does this affect maceration period?
- Premium wines to be kept long term need higher tannin levels so maceration period is longer - several days-weeks
What is the maceration period for grapes from new vines and why?
Short
- Vines are supple and contain little tannin
Why should rough manipulation of grapes be avoided in the production of red wine?
There is violent extraction of grassy characteristics
What is punching down in the production of red wine?
Breaking up the layer of skins/stems that form on the top of fermenting red wine
The must is also drained from the bottom and sprayed on top of skins
What is an alternative fermentation method of red wine to crushing/maceration?
Carbonic Maceration
What is carbonic maceration?
- No initial crushing
- fruit is allowed to ferment spontaneously using enzymes instead of yeast to break down sugars when starved of oxygen then placed under a protective layer of CO2
How does fermentation occur during carbonic maceration?
Weight of grapes and process causes some juice release
- Most fermentation is inside the grape
- only reaches about 2% ABV then grapes are presses and fermentation completed using yeast
How does carbonic maceration affect the final wine?
Wines are softer and less astringent
Gives fruity, supple, richly coloured reds
Suited to grapes that give hard acidic wines because process breaks down some of the malic acid
Give examples of wine made using carbonic maceration
Wines are for drinking young:
Beaujolais
Zinfandel
Rioja
What is pressing wrt red wine production?
- Pressing not undergone immediately.
- Allowing fermentation and maceration first, wines develop colour
- not always carried out for reds if astringency is high
How much of the juice is removed during crushing in red wine production and what is this referred to as?
60-70%
Free run - it is separated from the pomace into another tank/barrel
What is vin de goutte made from and what does it mean?
From the free run
Wine of draining
What can be pressed during red wine production with the same type of presses as white?
Pomace
How are champagne and rose pressed?
as whole clusters without initial crushing step
How is vin de presse pressed and what is produced?
Wine of pressing
pomace pressed gently releases good quality
- Dark tannic wine is rich in desirable extracts and flavours but may need fining to reduce astringency and remove solids
What are most wines in terms of pressed/non pressed composition ?
Wine of draining is blended with wine of pressing.
Many wines are 85% free run wine and 15% pressed
What type of wine has a further press?
Cheap table wine
What is malolactic fermentation in the production of red wine?
It is carried out with bacteria living in the wine
- Secondary fermentation of malic to lactic and CO2 to soften wine - adds to complexity of wine and increases its stability (lactic acid is stable )
Why is malolactic fermentation encouraged in red wines?
Malic acid content is usually high
How long does malolactic fermentation take and what are the conditions?
A few weeks
18-20 C
Cellar temp is usually raised to initiate secondary fermentation
In European cellars how long do wines mature for before secondary (malolactic) fermentation can occur?
6 months
- happens in the spring following the vintage
How are red wines matured/ why?
High quality reds = in oak for vanilla and other flavours.
Length of time in barrel is crucial decision and wine is regularly tasted to judge exact length of time.
When is red wine racked and what does this mean?
During its maturation period
- its racked every few months by transferring to clean sterile barrels, leaving the sediment behind and providing some aeration of the wine
What is fining in red wine production and when does it occur?
- POST RACKING/MATURING
- Used to clarify wine
- can use egg whites, bentonite clay or other types of finings to carry undesirable solids to the bottom
- Also removes proteins that cause haze and reduce astringency and/or bitterness
When does filtration occur in red wine and what happens?
Before bottling
- Guarantees stability under adverse conditions, such as during transportation but it is claimed that it strips wine of character
What is finishing wrt red wine?
Once wine is stable it’s bottled
What is red wine vulnerable to until the bottle is corked?
Oxygen
What type of ageing is barrel ageing in red wine and what does this mean?
Oxidative ageing
- Encouraging complex reactions between acids, sugars, pigments, tannins and other components
What type of aging is bottle aging in red wine and what does this mean?
Reductive aging
- No oxygen and has different complex reactions with these components, and at a much slower rate = hence wine laid down for long periods of time
When does pasteurisation occur in red wine and what affects it?
Carried out before bottling - only used for cheap wines not intended to mature further
- Good sterile handling and fine filtration means pasteurisation is being phased out in modern wineries
- this means sines will still be alive in bottle
At how many ppm does wine taste oxidised and what does this mean?
8.6
Tastes flat, lack of complexity and has cooked fruit flavours
What is the preferred level of oxygen in a bottle?
6ppm
How is oxidation in wine prevented?
Wine is sealed prior to serving
What happens to wine when it is starved of oxygen?
Usually red
- Off-putting mercaptan (naturally occuring putrid compound)
OR
- Sulfide smells
What happens to wine if it is allowed to oxidise after serving?
Acetobacter will convert the ethanol to acetic acid and wine will taste vinegary
How is vinegar made industrially?
Malt vinegar is unhopped beer
Red wine vinegar is red wine where acetobacter has converted ethanol to acetic acid
Why are wines decanted before serving?
- Removes sediment from older wines (ensures clarification and reduces astringency)
- Develops aroma and flavour of younger wines by reacting with oxygen
What type of wine should not be decanted or only be decanted for a short amount of time?
Extremely delicate older wines
What type of wine benefits from decanting?
Old whites
What stages of wine production is oxygen avoided and why?
Crushing/pressing
- Early oxidation of grape juice affects both quality (flat taste) and colour changed
When is oxygen required in wine production and why?
At the start of fermentation
- For yeast activation and growth - yeast life cycle
Is oxygen involved in barrel maturation? Give detail?
- Small amounts through the wood and racking aeration
- Deepens colour, smooths the flavour and makes wine more stable
- Barrels continuously topped up and when bottles are filled, fill heing is controlled for oxygen content
Can sealed wine oxidise?
Wine is sealed in bottle but no sealing is perfect so yes eventually
How is oxygen removed from wine after the bottle is open?
Vacuum system
What are oxidative wines?
White wines which have been carefully exposed to oxygen at specific times during the winemaking process and maturation
Why do many wineries want to exclude oxygen as much as possible from the wine making process?
To retain fruity flavours
What flavours do oxidative wines have?
Nutty, yeasty, and savoury
What is one of the most famous oxidative wines?
Jura - France
What is the negative of oxidative wine production?
It can spoil very easily - shows the skill of the wine maker
Summarise wine making (6)
- White wines can be aged in a range of woods but oak is most common
- White wines will still contain yeast during maturation so can be aged
- Colour of wine can change depending on age and region
- Red wines’ colour is red due to maceration with skins
- Tannins are important compounds in red wines introduced through the stem, seeds, skins and barrels
- Control of oxygen levels during maturation is essential
