WSET Diploma D1 Exercises (Specific Options for Red and Rosé Winemaking)

Answer

a) Cold soaking: crushed black grapes are chilled (to around 4–10°C) for typically 3–7 days before fermentation, usually with punching down or pumping over to mix the skins and juice. In water (not alcohol) colour and fruit flavours are extracted with relatively little tannin, so it suits varieties such as Pinot Noir. It is gentle and easy to control, so it suits premium wines. However, it takes tank time and energy for cooling, so it is rare in cheap, high-volume wines, and the must must be kept cold and mixed to limit the risk of spoilage.

b) Thermovinification: the must is heated (to around 50–60°C, sometimes higher) for anywhere from a few minutes to several hours. The juice may then be pressed off and fermented like a white wine for a fruity, low-tannin style, or fermented on the skins for more tannin. It extracts colour and flavour quickly and destroys the oxidative enzyme laccase, which is useful for rotten grapes. However, wines pressed off before fermentation tend to have unstable colour (too little tannin to bind the anthocyanins), so they suit inexpensive wines for early drinking, and critics say it reduces subtle varietal character.

c) Flash détente: the grapes are heated quickly (to 85–90°C) and then cooled very quickly under a vacuum, all in as little as two minutes, which makes the skin cells burst. This gives very fast extraction of colour and flavour; the short time at high temperature limits cooked flavours, and it also destroys laccase and can be used to treat smoke taint. The drawbacks are the high equipment cost (so it is mainly used in high-volume wineries) and, according to critics, a loss of subtle varietal character.

Grading Criteria

• For explaining what cold soaking is (chilled, around 4–10°C, for 3–7 days before fermentation), you get 1 point.
• For stating that cold soaking extracts colour/flavour with little tannin, you get 1 point.
• For a disadvantage of cold soaking (tank time, cooling cost, spoilage risk), you get 1 point.
• For explaining what thermovinification is (heating the must, then pressing), you get 1 point.
• For stating that thermovinification extracts colour quickly, you get 1 point.
• For explaining that heating destroys laccase, so it is useful for rotten fruit, you get 1 point.
• For a disadvantage of thermovinification (unstable colour, wines for early drinking, loss of subtle varietal character), you get 1 point.
• For explaining what flash détente is (rapid heating, then a vacuum), you get 1 point.
• For stating that flash détente gives very fast extraction (or limits cooked flavours, or treats smoke taint), you get 1 point.
• For a disadvantage of flash détente (equipment cost, loss of subtle varietal character), you get 1 point.

Answer

a) Punching down (pigeage): the cap is pushed down into the liquid by hand or machine. It is gentle and suits small, open-top vessels (e.g. Pinot Noir), but by hand it is labour-intensive and is difficult in large tanks.

b) Pumping over (remontage): wine is drawn from the bottom of the tank and sprayed over the cap. It suits large tanks, can be pre-programmed (little labour) and can be done with air contact (good for yeast health and avoiding reductive off-flavours) or without it. However, the extraction is very gentle, so punching down or rack and return is usually also needed.

c) Rack and return (délestage): the fermenting wine is drained into another tank, so the cap settles, and then it is returned over the cap. It breaks up the cap and is extracts more than either pumping over or punching down, so it is used only 1–3 times during fermentation, for wines with medium to high colour and tannin (e.g. Cabernet Sauvignon, Syrah); it also aerates the wine, and seeds can be removed. It needs a clean spare tank and labour (it cannot be fully automated).

d) Ganimede® tanks: the carbon dioxide from fermentation collects under a funnel-shaped partition and is released periodically, breaking up and soaking the cap. The cap is broken up quickly, so extraction is relatively high (suited to e.g. Cabernet Sauvignon, Syrah), and the process can be fully automated, needing less labour than rack and return; the tanks cost a little more than ordinary steel tanks.

e) Rotary fermenters: horizontal, closed tanks that rotate, with internal blades breaking up the cap. Extraction is very effective and labour needs are low (they can be programmed), but the tanks are relatively expensive, so they are mostly used for large volumes of inexpensive to mid-priced wines; gentler, more precise methods are usually preferred for premium wines.

Grading Criteria

• For explaining punching down, you get 1 point.
• For an advantage or disadvantage of punching down, you get 1 point.
• For explaining pumping over, you get 1 point.
• For an advantage or disadvantage of pumping over, you get 1 point.
• For explaining rack and return, you get 1 point.
• For an advantage or disadvantage of rack and return, you get 1 point.
• For explaining how Ganimede® tanks work (CO2 trapped and released), you get 1 point.
• For an advantage or disadvantage of Ganimede® tanks, you get 1 point.
• For explaining rotary fermenters, you get 1 point.
• For an advantage or disadvantage of rotary fermenters, you get 1 point.

Answer

a) Must concentration: in difficult (wet) vintages, some water can be removed from the must by reverse osmosis, vacuum evaporation or saignée (bleeding off juice). This increases the concentration of sugar, colour, tannin and flavour, but it also concentrates any faults or unripe characters. It also reduces the volume of wine made (bled-off juice can be used for rosé), and these practices are regulated in many regions.

b) Co-fermentation: fermenting two or more varieties in one vessel. The term usually means adding a little white fruit (up to about 5 per cent) to a red fermentation, as with Syrah and Viognier in Côte-Rôtie, to improve colour stability and add aroma. It is not common for premium Cabernet Sauvignon, which is usually fermented by variety and plot so that the winemaker can decide the final blend later (e.g. Bordeaux). It costs little, but research results are mixed and too much white grape dilutes the colour.

c) Post-fermentation maceration: the wine is left on the skins for days or weeks after fermentation. This allows further extraction and polymerisation of tannins, which can make the texture softer and rounder and helps structure for long ageing; but it needs tank space and careful tasting to avoid over-extraction.

Grading Criteria

• For naming a method of must concentration (reverse osmosis, vacuum evaporation, saignée), you get 1 point.
• For explaining when it is used (dilute must in wet vintages), you get 1 point.
• For explaining that it increases concentration of sugar, colour, tannin or flavour, you get 1 point.
• For pointing out a disadvantage (concentrates faults, reduces the volume of wine, or is regulated), you get 1 point.
• For explaining what co-fermentation is, you get 1 point.
• For stating that premium Cabernet Sauvignon is usually fermented separately by variety/plot, you get 1 point.
• For explaining that this gives control over the final blend, you get 1 point.
• For explaining what post-fermentation maceration is, you get 1 point.
• For stating that it extracts more tannin or allows tannins to polymerise (softer texture), you get 1 point.
• For a further point (structure for ageing, tank space, risk of over-extraction), you get 1 point.

Answer

In carbonic maceration, whole, uncrushed bunches are placed in a vessel filled with carbon dioxide. Without oxygen, an enzymatic (intracellular) fermentation starts inside each berry, producing a small amount of alcohol (about 2%) and distinctive aroma compounds. The berries then split, are pressed, and the juice finishes fermenting with yeast, usually without skins.

Impact on style: wines have good colour but low tannin (little tannin is extracted at only about 2% alcohol), with a soft, fruity style and distinctive aromas of kirsch, banana, bubblegum or cinnamon. Advantages: the wine is ready to drink early, malic acid can fall by up to 50 per cent (lower acidity), and the method can improve grapes from high yields or that are not fully ripe (e.g. Gamay in Beaujolais Nouveau). Oak is usually not used, which keeps costs low. The wines are best drunk within a year and are not especially complex.

Grading Criteria

• For stating that whole, uncrushed bunches are used, you get 1 point.
• For stating that the vessel is filled with carbon dioxide (no oxygen), you get 1 point.
• For explaining that fermentation starts inside the berries (intracellular), you get 1 point.
• For stating that a small amount of alcohol (about 2%) is produced inside the berries, you get 1 point.
• For explaining that the grapes are then pressed and fermentation is completed by yeast, you get 1 point.
• For stating that the wines have low tannin, you get 1 point.
• For stating that the wines have good colour, you get 1 point.
• For naming typical aromas (kirsch, banana, bubblegum, cinnamon), you get 1 point.
• For stating that the wines are ready to drink early, you get 1 point.
• For giving an example (Beaujolais/Gamay) or noting limited ageing potential, you get 1 point.

Answer

In semi-carbonic maceration, whole bunches are put into a vessel without adding carbon dioxide. The weight of the grapes crushes the berries at the bottom, and the juice released starts a normal yeast fermentation. The carbon dioxide from that fermentation fills the vessel, so the whole berries above undergo intracellular fermentation. After pressing, fermentation is completed.

Impact on style: the wine is a mix of the two styles: it has some of the soft, fruity, low-tannin character of carbonic maceration, with more structure and less obvious ‘carbonic’ aroma. Advantages: it is simpler and cheaper (no need to add CO2) and is widely used in Beaujolais; the proportion of each type of fermentation is harder to control.

Grading Criteria

• For stating that whole bunches are used and no CO2 is added, you get 1 point.
• For explaining that grapes at the bottom are crushed by the weight above, you get 1 point.
• For explaining that this juice starts a normal yeast fermentation, you get 1 point.
• For explaining that CO2 from this fermentation fills the vessel, you get 1 point.
• For explaining that the whole berries above undergo intracellular fermentation, you get 1 point.
• For stating that the grapes are pressed and fermentation is completed, you get 1 point.
• For stating that the wine combines characteristics of carbonic and normal fermentation, you get 1 point.
• For a point about tannin/fruit/aroma (soft, fruity, less obvious carbonic aromas), you get 1 point.
• For an advantage (simpler or cheaper), you get 1 point.
• For an example (Beaujolais) or a disadvantage (less control), you get 1 point.

Answer

a) Direct pressing: black grapes are pressed straight away, so the juice picks up only a little colour during pressing. This gives very pale, delicate rosés (often called vin gris, e.g. many Provence rosés). Inert gas is often used in the press to protect the juice from oxygen.

b) Short maceration: crushed black grapes are left with the juice for a short time (a couple of hours to a few days) before the juice is drained off and fermented like a white wine. The length of maceration controls the colour and often gives deeper, more flavourful rosés (e.g. Tavel).

c) Blending: a small amount of red wine is blended with white wine. This is not allowed for still rosé in most of the EU; exceptions include rosé Champagne and Franciacorta, and it is common outside the EU. It is simple and cheap, and the colour is easy to control because both wines are already fermented.

d) Saignée: some juice is bled off from a tank of red wine must early in maceration and fermented as rosé. This also concentrates the remaining red wine. The rosé is a cost-effective by-product, but because the grapes were grown and picked for red wine, the juice may be less suited to rosé (e.g. lower in acidity).

Grading Criteria

• For explaining direct pressing, you get 1 point.
• For stating that direct pressing gives very pale, delicate rosés (or an example), you get 1 point.
• For explaining short maceration and the typical length, you get 1 point.
• For stating that the length of maceration controls colour (or that the juice is then fermented like a white), you get 1 point.
• For explaining that blending means adding red wine to white wine, you get 1 point.
• For stating that blending is not permitted for still rosé in most of the EU, you get 1 point.
• For stating that blending is permitted for rosé Champagne (or Franciacorta, or outside the EU), you get 1 point.
• For explaining saignée (bleeding off juice from red must), you get 1 point.
• For stating that saignée concentrates the remaining red wine, you get 1 point.
• For noting that saignée rosé is a by-product whose juice may be less suited to rosé (e.g. lower acidity), you get 1 point.