Specific Options for Red Winemaking Flashcards
Specific Options for Red Winemaking
Factors that affect extraction are:
- Temperature – higher temperatures result in greater extraction
- Time on skins – generally, the longer the juice/wine remains in contact with the skins the
greater the extraction - The medium in which the extraction is taking place (tannins are most soluble in alcoholic solutions (e.g. wine), whereas anthocyanins are most soluble in aqueous solutions (e.g. grape must).
Specific Options for Red Winemaking
Anthocyanins, Tannins and Oxygen:
Anthocyanins = source of colour in young red wines:
- Become more stable when they combine with tannins, resulting in greater colour stability.
- Oxygen facilitates this reaction: micro-oxygenation and barrel ageing promote colour stability.
- Anthocyanins and anthocyanin-tannin compounds change in composition over time
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Specific Options for Red Winemaking
Maceration before fermentation:
The key aim of maceration before fermentation is to extract colour and flavours, without extracting tannins: anthocyanins are most soluble in grape must, whereas tannins are more soluble in alcoholic liquids
Cold maceration:
- Cold soaking / Cold maceration / Pre-fermentation maceration.
- Chilled to around 4–10°C (reduce the rate of oxidation / the threat from spoilage organisms / risk of a spontaneous fermentation starting)
- last 3–7 days
- punching down and/or pumping over to mix up the skins and juice, aiding extraction
- avoids the growth of spoilage organisms that need oxygen, such as acetic acid bacteria, on the top of the cap of skins.
- suitable for premium wines. The cold temperatures result in a slow extraction
Macerations Using heat:
higher temperatures = greater extractio (and quicker)
- Thermovinification: heating the must to around 50–60°C and sometimes higher (from a number of minutes to several hours
- Flash détente, destemmed grapes are quickly heated to 85–90°C and then rapidly cooled under a vacuum (in as little as two minutes)
- The process bursts the cells in the grape skins, allowing a very rapid extraction of anthocyanins and flavours.
- limits the risk of ‘cooked’ flavours developing
- Expensive vacuum system
- Can also be used as a treatment for smoke taint
Specific Options for Red Winemaking
Maceration during fermentation:
- The grape skins rise to the top of the liquid and remain there, forming the CAP:
Without mixing = skins spend the fermentation macerating in the same small volume of liquid that surrounds them, that become saturated with colour, tannins and flavours and therefore dissolution of these compounds into the liquid would gradually stop. - Dry cap would allow bacteria to convert alcohol into unwanted acetic acid.
- Most of the techniques used to move the cap also aerate the must: help to avoid the production of reductive sulfur compounds.
- Distribute the heat produced during fermentation: essential for temperature monitoring and control
- Winemaker can alter the frequency of the mixing and the duration of the mixing
- Timing of the mixing within the fermentation can influence what compounds are extracted (mixing at the start extract more colour / mixing at the end extract more tannins)
- Warmer fermentations will extract more than cooler fermentations
Specific Options for Red Winemaking
Cap management techniques
Punching down – A plunger is used to submerge the cap of grape skins in the liquid (by hand or by a mechanised plunger)
- by hand = is labour intensive / best suited to low- volume production of premium wines possible in relatively small, open top vessels
- In French: PIGEAGE
Pumping over - Juice/wine is taken from near the bottom of the vessel and sprayed over the cap of skins (Usually around one-third to one-half of the liquid in the vessel)
- Very gentle extraction (sprays the liquid over the cap, rather than breaking it up)
- Aerobically: by splashing the wine against the
inside wall of the open vat (exposes the must to oxygen, which can be beneficial for yeast health and avoidance of reductive off-flavours)
- Anaerobically: in closed vessels by attaching the hose 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
- In French: REMONTAGE
Rack and return - the juice is pumped from one vessel into another vessel.
- higher extraction than Punching down and Pumping over (usually done max 1-3 times)
- suited for medium to high levels of flavour, colour and tannin wines (Cab Sav/Syrah..)
- In French: DELESTAGE
Ganimede Tanks - These specialised tanks bubble CO2 up through the must/wine.
- Breaks up the cap quickly = relatively extractive and suited to producing wines with medium to high levels of colour, tannins and flavour intensity
- Oxygen can be used instead of CO2
- expensive
Rotary fermenters - Horizontal, closed, stainless steel tanks. The whole tank rotates and internal blades break up the cap and ensure adequate mixing.
- very effective at extracting
- can be programmed = low labour requirements
- commonly used for high-volume, inexpensive or mid-priced wines
- expensive
Specific Options for Red Winemaking
Other maceration Options During fermentation
Must concentration - Drawing off some of the juice just after crushing and before the start of the ferment, concentrating the remaining must (increasing the levels of colour, flavours and tannins)
- Juice that is removed is typically light in colour, flavour and tannin and can be used to make rosé = SAIGNEE method
Co-fermentation - Process of fermenting different grape varieties together
in the same vessel.
- Small proportion of white grapes (typically up to 5 per cent) within a red wine fermentation (Cote Rotie: Syrah + Viognier)
- Some of the phenolic compounds found
in white grape varieties can increase colour intensity and stability through binding with anthocyanins
Specific Options for Red Winemaking
Whole Berry/Bunch fermentations
Whole bunches of grapes or whole destemmed grapes (‘whole berries’) / entirely uncrushed fruit or just a small proportion in a crushed fruit fermentation.
Whole bunches:
- the grapes must be hand harvested
- Stems must be fully ripe: can add ‘spicy’ or ‘herbal’ flavours and some tannins (unripe stems can add unpleasant green flavours and bitter tannins)
- Objective is to create an oxygen-free environment for the uncrushed fruit
- The grapes change from aerobic respiration to anaerobic metabolism: some of the sugar in the grapes is converted to alcohol without the involvement of any yeast (intracellular fermentation)
- Malic acid within the grape is also broken down to create ethanol (can reduce the malic acid levels by up to 50% lowering the total acidity and raising the pH of the must/wine.
- Glycerol levels increase (add texture, and a range of distinctive aromas including kirsch, banana, bubble gum and cinnamon)
Specific Options for Red Winemaking
Carbonic Maceration
Carbonic maceration:
This involves placing only whole, uncrushed bunches into vessels that are filled with CO2 to remove all the oxygen
- This causes the intracellular fermentation to start, producing about 2% abv
- At this point, either the grapes are crushed in the normal way or the grape skins start to split and the grapes release their juice.
- Normal fermentation commences: juice is generally drained immediately (no further maceration on the skins)
- Grapes are pressed to separate the juice from the skins. The free run juice and press juice are typically blended
- Yeast then complete the fermentation off the skins.
- extracts colour from the grapes, but little tannin (ony 2% abv)
- low tannins with distinctive notes from intracellular fermentation, alongside the fruit notes from the grape variety.
-suitable for fruity, low tannin profile wines that are best consumed within a year after harvest
Specific Options for Red Winemaking
Semi-carbonic Maceration
Similar to Carbonic but does not involve filling the vessel with CO2.
- The grapes at the bottom of the vessel are crushed under the weight of the grapes above and some juice is released.
- Ambient yeast start to ferment the juice (cultured yeast can also be added): This fermentation produces CO2, which fills the vessel and the remaining intact grapes undergo carbonic maceration.
- As the intact grapes begin to split and release their juice, the grapes are pressed and the yeast complete the fermentation off the skins.
- Alcoholic fermentation may continue on the skins + punching down or pumping over for more concentration
- ## Alcoholic fermentation may be followed by a post-fermentation maceration and/or maturation in oak to add complexity
Specific Options for Red Winemaking
Whole berries-bunches + crushed fruit:
Mix whole berries/bunches with crushed grapes in the fermenting vessel at the start of the fermentation
- Whole berries/bunches are largely submerged by the crushed grapes and kept away from oxygen = intracellular fermentation takes place
- The whole berries/bunches are progressively crushed during the fermentation as the cap is regularly punched down
- Post-fermentation maceration and/or oak maturation may follow
- Give a smoother texture and more vibrant and fresh primary aromas (than crushed fruit fermentations).
Specific Options for Red Winemaking
Fermentation temperatures
Red wines are usually fermented at warmer temperatures than white wines because higher temperatures help to promote extraction. Warm temperatures = evaporation of volatile, fruity aromas
- cool temperatures (e.g. 20°C / 68°F) = fruity, low tannin wines
- slightly warmer temperatures (e.g. 30°C / 86°F) = greater extraction to produce wines with the concentration and tannin structure to age
Specific Options for Red Winemaking
Post fermentation maturation
- leave the wine macerating on the grape skins (from a few days to a few weeks) after fermentation.
- To further extract tannins and encourage the polymerisation of tannins, with the aim of improving tannin structure and texture and the wine’s ageing potential
Specific Options for Red Winemaking
Pressing the grapes
Pressing separates the wine from the skins and therefore takes place when no more extraction is desired
The free run wine (fruity flavours + low tanninsd) will be drained from the fermentation vessel, and the mass of grape skins then removed for pressing
Press wine = to add extra colour, flavour and tannins
Carbonic maceration = pressing may occur when the fermenting must reaches 2% abv
Pressed after a period of post-fermentation maceration = maximise the tannin structure of the wines.
Press just before the end of alcoholic fermentation (wine will finish fermenting in barrels) = lead to a better integration of oak flavours and rounder mouthfeel
Specific Options for Red Winemaking
Maturation in wood
- Inexpensive wines = obtain the spicy flavours of wood from oak alternatives (staves, chips) = cheap, quick
- Mid-market, premium and super-premium
red wines = matured in oak vessels for a range of time (between six months and two years )
A proportion of new oak may be used
- flavours of vanilla, cloves, etc.
- enhanced complexity
- Gentle oxidation = soften tannins + development of tertiary aromas and flavours that can enhance complexity and quality
