Specific options for red winemaking

Question 1

Specific options for red winemaking

Answer 1

General aim is to extract anthocyanins, tannins and flavor so the the wine is suitably concentrated and balanced, but no extracted too much

Question 2

Factors that affect extraction in red winemaking

Answer 2

• Temperature - higher temperatures result in greater extraction
• Time on skins - longer juice/wine remains in contact with the skins the greater extraction
• Management of skins and juice - the more the skins are mixed through the juice, the greater the extraction
• The medium in which the extraction takes place - tannins are most soluble in alcoholic solutions (wine) anthocyanins are most soluble in watery solutions (must)

Question 3

Anthocyanins, tannins and oxygen

Answer 3

Anthocyanins are the source of color in young red wines

As single molecules they are not very stable and the colour they provide may be lost in the process of different winemaking techniques, like lees aging or additions of so2

Anthocyanins become more stable when they combine with tannins, resulting in greater colour stability, this reaction is facilitated by oxygen. Therefore winemaking processes that encourage gentle oxidation of wine (barrel aging) can help to promote colour stability

Anthocyanins and tannin compounds change in composition over time, and wine become paler turning from ruby to brown

Question 4

Maceration before fermentation

Answer 4

Key aim is to extract colour and flavour, without extracting tannins

Anthoucyanins are soluble in must and wine, but tannins are more soluble in alcoholic liquids (wine) an therefore not readily extracted at this point of the process

Cold soaking

Macerations using heat

Question 5

Cold soaking

Answer 5

Also known as cold maceration or pre-fermentation

Juice/skins chilled (4-10) to reduce the oxygen rate, microbial spoilage and spontaneous fermentation

Last 3-7 days, usually with punching down or pumping over to mix skins and juice, aiding extraction and also helps to avoid growth of spoilage microbes (acetic acid bacteria) that need oxygen, on the top of the cap of the skins

Gentle technique, suitable for premium wines. Cost of energy required to chill the juice and time taken for cold soaking

Cold temperatures result in slow extraction, which can easily be monitored to achieve the level of extraction desired

Commonly used for Pinot Noir, as it promotes colour intensity (because of low levels of anthocyanins in this variety) or other colour extractions without risking the extraction of high levels of tannins

Question 6

Macerations using heat

Answer 6

Higher temperatures lead to greater extraction

Key techniques are flash detente and thermovinification

Both techniques the juice will be pressed off the skins before fermentation if a low tannin, fruity style is desired. However, wines produces this way tend to have issues with colour instability because there are not enough tannins anymore to bind with the anthocyanins to form a more stable colour intensity, therefore often used for inexpensive wines

May also be used as a blinding component in higher quality wines, to add fruity flavours or the juice may be fermented for a period of time on the skins if a style with more tannins is desired

Both techniques can be beneficial if grapes are affected by grey rot, as high temperatures denature oxidative enzymes produced by rot

Both techniques are said to intensify fruitiness of the wines, but critics feel that this technique can lead to ad reduction in more subtle varietal characters

Question 7

Flash detente

Answer 7

Destemmed grapes are quickly heated to 85-90 and then rapidly cooled under a vacuum (2 min)

Short time at high temperatures limit the risk of cooked flavors developing

The process burst the cells in the grape skins, allowing a vary rapid extraction of anthocyanins and flavours

Vacuum system is expensive to boy, thends to be used at high volume wineries where large throughput may justify the costs

Can also be used as a treatment for smoke taint

Question 8

Thermovinification

Answer 8

Heating the must to around 50-60 and sometimes higher

Time may vary from a few minutes to several hours; higher temperature, shorter maceration

Question 9

Maceration during fermentation

Answer 9

Vast majority of red wine is fermented on the skins

Important to mix the skins with the juice or wine during fermentation for the following reasons:

• Grape skins float at the top of the liquid, buoyed by carbon dioxide (cap)
• Without mixing, skins would spend the fermentation maceration in the same small volume of liquid that surrounds them becoming full with colour, tannins and flavored and therefore dissolution of these compounds in the liquid would stop
• The process of mixing disturbs the juice and skin so that juice that is not full with these compounds comes into contact with the skins

Conclusion: Mixing promotes extraction and also helps to distribute the heat produced during fermentation and is therefore essential for temperature control

Question 10

Choices regarding cap management techniques

Answer 10

Have impact of the style of wine produced

Different techniques;
Punching down
Pumping over
Rack and return
Ganimede tanks
Rotary fermentations 

Winemaker can alter the frequency of the mixing and the duration of the mixing; pumping over the must three times a day for 15 min will extract more than 10 min once a day

Timing of the mixing during fermentation can influence what compounds are extracted; more mixing at the start and less mixing at the end will extract more colour and less tannin, whereas mixing more at the end of fermentation will extract a greater amount of tannin

Temperature also has a role; warmer ferments will extract more than cooler ferments. Tannin extraction can be reduced by cooling the wine near the end of fermentation when tannins are most likely to extracted

Question 11

Punching down

Answer 11

Plunger is used to submerge the cap of skins in the liquid

Either carried out by hand or by a mechanized plunger

Carried out by hand is labour intensive, expensive and more suitable to low-production of premium-wines

Gentle process and used on several varieties

French name, pigeage

Question 12

Pumping over

Answer 12

French name remontage

Juice/wine is taken from near the bottom of the vessel and sprayed over the cap of skins. Usually one-third to one-half of the liquid is pumped and sprayed over the cap

The juice extracts colour, tannins and flavors from the cap of skins as it passes through

Gentle extraction, because the juice is sprayed over, rather than braking up the cap. Usually punching down and rack and return is also required to extract enough colour, flavour and tannin

Can be carried out aerobically, splashing the wine into a new container and then pumping it from there up over the the cap, this exposes the must to oxygen, which can be beneficial for yeast health and avoidance of reductive off-flavors such as rotten eggs

Anaerobically, pumping over in closed vessels by attaching the hose to a tap of the top of the vessel or by keeping the hose close to the cap of skins in an open vessel

Pump overs can be programmed to occur at certain times and for certain durations, reducing the need of labour.

Question 13

Rack and return

Answer 13

French name, delestage

Similar to pumping over, but juice is pumped over from one vessel into another vessel, as the juice is being pumped out of the vessel the cap falls down the vessel

The juice is than pumped from the new vessel in the original vessel and sprayed over the skins, breaking up the cap mixing the juice ands skins

More extractive than pumping over or punching down, used along side pumping over and punching down only 1-3 times during fermentation

Commonly used for reds where medium to high levels of flavour, colour and tannin are desired (Cab Sauv, Syrah)

Not fully automated and requires labour to set up and monitor the process also requires a clan vessel to be available, which can be an issue in wineries that are operating at their peak capacity

Question 14

Ganimede tanks

Answer 14

Tanks that bubble up co2 through the must or wine

Pressure builds up under the cap until it bursts, this technique breaks up the cap quickly and is relatively extractive, suited if medium to high levels of colour, flavour and tannins are desired

Relatively new, but becoming increasingly common because it can be fully automated and therefore less labour intensive

Slightly more expensive than stainless steel tanks

Oxygen may be used instead of co2 if more oxygen exposure during fermentation is desired

Question 15

Rotary fermentations

Answer 15

Horizontal, closed, stainless steel tanks

Tank rotates and internal blades break up the cap and mix the must/wine with the skins. The horizontal orienting of the tank increases the surface area between the grape skins and juice

Very effective at extracting and thereof best suited if high levels of flavours, colours and tannins are wanted

Can be programed to rotate at certain times and certain amounts of time, labour requirement is low

Commonly used for high volume, inexpensive or mid-priced wines that are acceptable or good in quality

Relatively expensive compared to standard stainless steel tanks and therefore large volume of wined need to be fermented in them to make them cost effective

Question 16

Other maceration options during fermentation

Answer 16

Some less common ways to extract during fermentation

Question 17

Must concentration

Answer 17

French term saignee

Although not strictly a way of extraction, the levels of colour, flavour and tannins of the wine can be increased by drawing off some of the juice just after crushing and before the start of fermentation, concentrating the remaining must

Lowers the volume of red wine that will be made, which can have implications on the price of the wine; however, the juice that is removed (light in colour, flavour and tannin) can be used to make rose

Question 18

Co-fermentation

Answer 18

Process of fermenting different varieties in the same vessel (typically a small proportion of white grapes, 5%, within a red wine ferment) to take advantage of some of the phenolics found in white grapes that can increase colour stability and the contribution of aroma compounds (terpenes in Viognier, giving floral and fruity characteristic)

Originated in the Rhone Valley, with Cote Rotie being famous for fermenting Syrah and Viognier

Question 19

Whole bunch fermentation

Answer 19

Using uncrushed fruit/whole bunch in fermentation

Either whole bunches (hand harvest) or whole destemmed grapes (uncrushed)

Whole bunches –> Fully ripe stems (unwanted green and herbal flavors and tannins)

Winemakers can also add stems to provide some spicy flavor and tannins (not common for varieties with natural high tannins; Cab Sauv)

The aim of whole bunch/berry fermentation is to create an oxygen free environment for the uncrushed fruit, which has several outcomes:

• Grapes change from aerobic respiration to anaerobic metabolism
• In the anaerobic process, some of the sugar in the grapes is converted to alcohol without the involvement of any yeast –> Intracellular fermentation
• Malic acid is broken down to create ethanol, reducing the magic acid levels up to 50%, lowering total acidity and raising the pH in the must/wine
• Glycerol levels increase, adds texture, and aromas like kirsch, banana, bubblegum and cinnamon are likely to be created inside the grape

Whole Bunche/berry fermentation itself does not have a significant impact on the cost. However, its more likely that other parts of the production process (hand harvesting, use of oak) will have greater impact on the price of these wines

Question 20

Carbonic maceration

Answer 20

Whole uncrushed bunches placed in a vessel that is filled with co2 to remove all the oxygen, causing intracellular fermentation to start

Once 2% alcohol level has reached, grape skins start to split and the grapes release their juice, juice is drained off and grapes are pressed to separate the juice from the skins. The free run juice and press juice are typically blended

Than yeast will complete. the fermentation off the skins

Important:

• Extracts colour from the grapes, but little tannin (tannins are most likely to be extracted in the presence of alcohol)
• Typically low tannin wines, with aromas of kirsch, banana, bubble gum and cinnamon from intracellular fermentation, along the fruit notes for the grape variety
• Flavours of oak are usually not desired in this style of wine, keeping production costs relatively low

These wines are defined by their fruity, low tannin profile and best consumed within a year after harvest. This technique tends to be used for inexpensive and mid-priced wines. Beaujolais famous region (Beaujolais Nouveau)

Question 21

Semi-carbonic maceration

Answer 21

Slightly different from carbonic maceration, does not involve filling the vessel with co2

Vessel is filled with whole bunches, grapes at the bottom of the vessel are crushed by the weight of the grapes above releasing some juice

Ambient yeast starts to ferment the juice (cultured yeast can be used as well) producing co2, filling the vessel and the reaming intact grapes will undergo carbonic maceration

As the intact grapes split and release their juice, the rapes are pressed and yeast complete the fermentation off the skins

This technique is used when slightly more concentration, body and tannin (hence longer aging capacity) is desired

The alcoholic fermentation may continue on the skins and may involve some punching down or pumping over to extract more colour, flavour and tannins or the fermentation may be followed by a post-fermentation maceration and/or maturation in oak to add complexity (this will all have implications on the production costs)

This approach can lead to a better integration of the aromas from the intracellular fermentation and the aromas from the grape variety

Results in wines with more fruitiness and a softer mouthfeel than crushed fruit fermentations (fruity styles Pinot Noir, Gamay, Tempranillo)

Question 22

Whole bunch with crushed fruit

Answer 22

A mix of whole bunch/berry with crushed grapes in the fermenting vessel at the start of fermentation (stems must be ripe)

The whole bunch/berry fruit is largely submerged by the crushed grapes and therefore kept away from oxygen, which encourage intracellular fermentation to take place

More ‘carbonic’ characteristics can be achieved by raising the proportion of whole bunches/berries at the start of fermentation

The whole bunches/berries are crushed during the fermentation as the cap is regularly punched down

Similar to semi-carbonic maceration, a period of post-fermentation maceration and/or oak maturation may follow

Generally thought to give a smoother texture and more vibrant and primary aromas than crushed fruit ferments

Applied on a wide range of varieties and different qualities and prices

Question 23

Fermentation temperatures for red wine

Answer 23

Usually higher temperatures than white wines (warmer temp, higher extraction). However, higher temperatures can cause volatile, fruity aromas to evaporate, so depending on the style of wine, the right balance is important

Fruity, low tannin wines:
- Relatively cool temp 20

Wines with greater extraction structure and higher tannin levels, to age:
- Warmer temp 30

Temp can be controlled and monitored during the process, slightly cooler temperatures at the end of fermentation avoid excessive tannin extraction

Question 24

Fermentation vessels for red wine

Answer 24

Stainless steel, concrete or wooden vessels

Vessels can be open at the tope, needed for extraction techniques (punching down) or closed

If oak is used in fermentation its generally a large vat, although small barrels can also be used. Managing fermentation in wooden vessels is labour intensive and typically limited to premium and super premium wines

Stainless steel and concrete help to retain the fruit flavours

Wooden vessels are thought to give a rounder mouthfeel to the wine and least to better integrating of oak compounds during maturation