D1: Specific options for red winemaking Flashcards
Many of the choices in red winemaking are focused on the extraction of anthocyanins, tannins and flavours from the grape skins.
The level and nature of these components have a defining influence on the style of wine
** the general aim is to extract these compounds so that the wine is suitably concentrated and balanced, but not to extract too much
Factors that affect extraction are:
1) temperature: Higher temp = greater extraction
2) time on skins: longer the juice is in reaction with skins= greater extraction
3) Management of the skins and juice: more skins= greater extraction
4) The medium in which the extraction is taking place:
* tannins are most soluble in alcoholic solutions (wine)
* anthocyanins are most soluble in aqueous solutions (eg grape must)
Anthocyannins, tannins and oxygen:
1) Anthocyanins are the source of colour in young red wines
- - however as a single molecule they are not very stable and the colour they provide can be altered or lost in the process of different winemaking procedures (lees ageing or add of so2)
* * anthocyanins are more stable when they bind with tannins, resulting in greater colour stability
—- oxygen facilitates this reaction
2) winemaking processes that enables gentle oxygenation of the wine (barrel ageing…) can therefore help to promote colour stability
3) Anthocyanins and anthocyanin tannins compounds change in composition over time and the wine becomes paler and gradually changes from ruby through brown
* * this change is slower for anthocyanin tannin compounds than anthocyanins
Although the phelocs found in the skins of black grapes makes them less vulnurable to oxidation than white grapes.
Chilling still helps to slow down oxidation, as well as microbial spoilage, grapes may also be chilled now if cold soaking is planned
Maceration before fermentation:
The key aim= extract colour and flavours, without extracting tannins
tannins are more extracted in alcoholic liquids, so not extracted at this stage
you have:
- cold soaking
- maceration using heat
Cold soaking:
1) cold maceration or pre fermentation maceration
2) juice and skins typically chilled at 4-10°C, 39-50°f to reduce the rate of oxidation, microbial spoilage and spontaneous fermentation
3) the pre mac ferm can typically last 3-7 days
* usually with the use of pumping down or pumping over the skins and juice adding extraction
* * this also avoids the growth of microbes that need oxygen (acetic acid bacteria) on the top of the skins
4) cold soaking is a gentle technique, suitable for premium wines
5) cold temp results in slow extraction which can be easily monitored and controlled to achieve the level of extraction desired
- - comonly conducted on PN to promote colour intensity (low level of anthocyanins
6) Cost= chill the wine also time (valuable tank space)
- – not suitable for high volume inexpensive wines
Maceration using heat:
1) higher temp leads to greater extraction
2) two key techniques: flash détente and thermovinification
Thermovinification:
1) heating the must around 50-60°C 122-140°f and sometimes higher
2) time: range from several minutes to several hours
- - general the higher the temp the shorter the maceration
Flash détente:
1) destemmed grapes are quickly heated to 85-90°c 185-194°f and then rapidly cooled under a vacuum
2) this process takes place in as little as 2 minutes (the short times at high temp limits the risk of cooked flavours developping
3) the process burts the cells in the grape skins, allowing a very rapid extraction of anthocyanins and flavours
4) expensive to buy, tend to be used at high volume wineries, where the large throughput can justify its cost
With both techniques of maceration using heat, the juice may be pressed off the skins before ferm if a low tannin, fruity style is desired.
- the wines produced at this way tends to have issues with colour stability
** this is because there is not enough tannin to bind with anthocyanins and form more stable compounds
*** this process is suited for inexpensive high volume wines that are going to be consumed shortly after production
- ** it may also be used as a blending component in higher quality wines bringing juicy, fruity flavours to the blend
- alternatively the juice may be fermented for a period of time on the skins if a style with more tannins is desired
Both flash détente and thermovinification can be particularly benefical if the grapes are affected by botrytis (grey rot)
as the high temp denature oxidative enzymes (called laccase) produced by the rot
Flash détente can also be used as a treatment for smoke taint
** both techniques are said to intensify the fruitiness of the wines
Maceration during fermentation:
1) It is important to mix the juice or wine during fermentation for a number of reasons:
2) In a tank the grape skins typically float at the top of the liquid, buoyed by carbon dioxide (cap)
3) without mixing this means the skins spend the fermentation macerating the same small volume of liquid that surrounds them
* this liquid would become saturated (verzadigd) with colour, tannins and flavours and therefore dissolution of these compounds into the liquid would stop
4) Mixing disturbs the juice and the skins so that juice that is not saturated comes in contact with the skins to macerate
5) leaving the cap at the top of the liquid to dry out affects the further extraction
6) also helps to distribute the heat produced during fermentation and is therefore essential for temperature monitoring and control
Choises regarding cap management have a key influence on the style of the wine:
1) many different techniques
2) alter the frequency of the mixing and the duration of mixing
3) timing of mixing can influence the compounds extracted at the moment:
* more mixing at the start of fermentation and less at the end will give wines with more colour and less tannins
4) warmer temp will extract more than cooler (temperature controlled vessels allow temperature being adjusted during fermentation
* therefore tannin extraction can be reduced by chooling the wine near the end of the fermentation at the time when tannins are most likely to be extracted
Punching down:
1) a plunger is used to submerge the cap of grape skins in the liquid
2) by hand or mechanised plunger
3) by hand: labour intensive (with its expense that this entails)
* best suited to low volume production of premium wines
4) it is also only physically possible to puch down the cap and ensure adequate mixing of the skins in relatively small, open top vessels
5) gentle process and can be used on several grape varieties
6) often referred on its french name (pigeage)
Pumping over:
1) juice/ wine has taken from the bottom of the tank and sprayed over the cap of skins
2) usually 1/3-1/2 is pumped over and sprayed over
3) the juice extract tannin, flavour and colour as it passes through
4) gentle, because cap is not punched down
* but sometown punching down or rack and return is needed to extract sufficient colour, flavour and tannins
5) aerobically: splashing the wine into another vessel and then pumping it from there back over the cap of skins
* this expose the must to oxygen
* * can be benefical for yeast health and avoidance of reductive sulfur aromas like rotten eggs
6) anaerobically: closed vessels by attaching the hose (slang) to a tap at the top of the vessel or simply by keeping the hose close to the cap of skins in an open vessel
7) commonly used on black varieties, but also on white, for wines of all prices and is suitable for use on large vessels
* modern wineries have pumps and hoses installed at each tank and pump over can be reprogrammed to occur at certain times and for certain durations, reducing the need of labour
* ** remontage
Rack and return:
1) similar to pumping over
* juice to another vessel
* caps of the skins falls down
* juice back in the original vessel
* * breaks up the cap and mixes juice and skins thoroughly (grondig)
2) more extractive than pumping over or punching down
* for this reason rack and return may be only used 1-3 times during fermentation
3) most commonly used for red wines where med to high tannins are required (CS, Syrah)
4) cannot be fully automated, so labour intensive due the need for set up the monitor for the process
5) also clean vessel is required (this can be an issue for wineries who are at peak level capacity)
6) Delestage french
Ganimede Tanks:
1) specialised tank tha bubble Co2 or oxygen (if desired) through the must/wine.
* forms pressure under the cap until finally the cap burst
2) breaks the cap quickly, very extractive so suited for wines with med to high levels of tannins, colour, flavour intensity (CS syrah)
3) relatively new technique, but popular due its totally automatisation
4) slightly more expensive than normal stainless steel tanks
Rotary fermenters:
1) horizontal, closed, stainless steel tanks
2) the whole tanks rotates and break up the cap by its internal blades and ensure adequate mixing
3) the horizontal orientation of the tank increases the surface area between the grape skins and the juice
4) very extractive so best suited for the production of wines with high tannins, flavour and colour intensity (CS Syrah)
5) Can be programmed to rotate at certain times etc…
6) commonly used for high volume, inexpensive wines that produces wines with acceptable to good quality
* for premium wines with very good and outstanding quality, a more gentle technique that allows a little more precision
7) relatively expensive compared to stainless steel tanks, so large volumes of wine need to be fermented in them to make them cost effective
Must concentration (less common)
1) although not a strictly way of increasing extraction
2) the levels of colour, tannin and flavours can be increased by drawing off some of the juice after crushing and before fermentation
* concentrating the remaining must
3) this lowers a volume of wine that will be made from a set weight of grapes (implications to the price of wine)
4) the juice that is removed is typically lighter in colour, tannin and flavour and can be used to make rosé
* Saignée
Co fermentation:
1) fermenting different grapevarieties in the same vessel
* the practice generally refers to the fermentation of a small percentage of white grapes(5%) in a vessel with black grapes
2) It is to take advantage of some of the phenolic compounds found in white grapes who can bind with anthocyanins and therefore result in higher quality
3) also can contribute to flavour (eg terpenes in viognier can give floral and fruity characteristics)
4) however:
* addig too much can dilute the juice
* lower colour intensity
5) originated in the Rhône, where Syrah is fermented with viognier
*** in some cases it is only a blend of white and red wine to benefit from the fruity or floral note, and so the influence of colour stability is diminished
If whole bunches are used for fermentation it is important that the stems of the bunches are fully ripe.
1) stems can add flavours that are sometimes described as Spicy or herbal and can also add some tannins
* unripe stems can add unpleasant green flavours and bitter tannins
2) winemaker can also choose to add stems to provide some tannins and spicy flavours (if the grapevariety itself is not too high in tannins)
WHat is the objective of whole berry/ bunch fermentation ?
1) create an oxygen free environment for the uncrushed fruit
2) the grapes change from aerobic respiration to anaerobic metabolism:
* some of the sugar in the grapes is converted into alcohol
* * this occurs without the involvment of yeast and is called an intracellular fermentation
3) malic acid is also broken down to create ethanol, this lowers the total acidity and increases pH
4) glycerol levels increase, which can add texture and a range of distinctive aromas is created inside the grape (kirsch banana bubble gum cinnamon
*** here the cost is hand harvesting sorting of fruit …
There are three forms of whole berry bunch fermentation
1) carbonic maceration
2) Semi carbonic fermentation
3) whole bberries/ bunches without crushing fruit
Carbonic maceration:
1) Placing whole bunches into a vessel that than is filled with co2 to replace oxygen and start the intracellular fermentation
2) At 2% abv the skin burst and the grape release its juice
* at this time the juice is drained of and the skins are pressed
* * the free run juice and pressed juice are typically blended, yeast than complete the fermentation off the skins
3) Extracts colour of the grapes, but little tannin
* Only 2% abv and tannins are best extracted in the presence of alcohol
4) resulting wines: low tannins, distinctive notes of kirsch, banana, bubble gum and cinamon like spice from intracellular maceration allon side the fruity notes from the grape variety
* flavours of oak are less desired allong the fruity character of these wines
5) best consumable a year after harvest
* flavours are distinct but not especially complex
* * sometimes it improves grapes that are produced at high yields or not reached full ripeness
* ** technique: tends to be used for acceptable or good, inexpensive and mid priced wines (beaujolais nouveau)
