WSET Diploma D1 Exercises (General Winemaking Options)

Answer

Sulfur dioxide, which has strong anti-oxidative effects, is added at key stages—after harvest, after fermentation, and before bottling—to protect the wine from oxidation. It is thought to be more effective to add larger amounts at critical points rather than in small, gradual doses.

From a storage and maturation perspective, minimizing ullage in barrels by regularly topping them up with wine helps limit oxygen exposure. Stainless steel tanks are also beneficial for fermentation and aging, as they are impermeable to oxygen, unlike wooden vessels, which allow air to pass through. Additionally, wines sealed with screw caps experience minimal oxygen ingress during bottle aging, further preserving freshness.

The use of inert gases, such as nitrogen, carbon dioxide, or argon, is another important measure. These gases can be used to flush oxygen out of tanks, pipes, and presses or to fill the headspace of containers, preventing oxidation. Maintaining a cool winery environment also helps slow down oxidation reactions, as lower temperatures reduce the rate of oxidation.

Grading Criteria

• Sulfer dioxide
  • For pointing out that sulfur dioxide is added at key stages to prevent the effects of oxygen, you get 1 point.
  • For explaining that sulfur dioxide has strong antioxidant properties, you get 1 point.
  • For pointing out that the key stages are after harvest, after fermentation, and before bottling, you get 1 point.
  • For explaining that it is considered more effective to add larger amounts at critical points rather than small, gradual doses, you get 1 point.
• Storage
  • For pointing out that minimizing ullage in barrels by regularly topping them up with wine helps prevent oxidation, you get 1 point.
  • For explaining that this practice limits oxygen exposure, you get 1 point.
  • For pointing out that stainless steel tanks are used for fermentation and ageing, you get 1 point.
  • For explaining that stainless steel tanks are impermeable to oxygen, unlike wooden vessels, you get 1 point.
  • For pointing out that wine bottles are sealed with screw caps to minimize oxygen exposure, you get 1 point.
  • For explaining that screw caps allow minimal oxygen ingress during bottle aging, you get 1 point.
• Inert gas
  • For pointing out that using inert gases is another important measure to prevent the effects of oxygen, you get 1 point.
  • For listing an example of an inert gas, such as nitrogen, carbon dioxide, or argon, you get 1 point.
  • For explaining that these gases can be used to flush oxygen out of tanks, pipes, and presses or to fill the headspace in containers, you get 1 point.
• Cooling
  • For pointing out that maintaining a cool winery environment is another important measure to prevent oxidation, you get 1 point.
  • For explaining that lower temperatures slow down oxidation reactions, you get 1 point.

Answer

Sulfur dioxide is typically added at three key stages: after harvesting, after malolactic fermentation, and just before bottling. It is generally considered more effective to add larger amounts at these critical points rather than in small, incremental doses.

Sulfur dioxide influences wine quality in several ways. Primarily, it protects against oxidation, helping to preserve a fresh, fruity wine style. Additionally, it stabilizes the wine by preventing microbial spoilage, ensuring long-term quality and stability.

However, precautions must be taken, as some people may experience allergic reactions even at very low concentrations (10 mg/L or more). Legal limits are in place to regulate the maximum allowable levels of sulfur dioxide in wine. Overuse can also diminish the wine’s aroma, negatively impacting its overall sensory profile.

Grading Criteria

• When
  • For pointing out three key stages as after harvesting, after malolactic fermentation, and just before bottling, you get 1 point each, totaling 3 points.
  • For explaining that it is generally considered more effective to add larger amounts at these critical points rather than in small, incremental doses, you get 1 point.
• How to impact
  • For pointing out that sulfur dioxide protects against oxidation, you get 1 point.
  • For explaining that this helps preserve a fresh, fruity wine style, you get 1 point.
  • For pointing out that sulfur dioxide stabilizes the wine by preventing microbial spoilage, you get 1 point.
  • For explaining that this ensures long-term quality and stability, you get 1 point.
• Precautions
  • For pointing out that some people may experience allergic reactions even at very low concentrations, you get 1 point.
  • For explaining that legal limits are in place to regulate the maximum allowable levels of sulfur dioxide in wine, you get 1 point.
  • For pointing out that overuse of sulfur dioxide can also diminish the wine’s aroma, negatively impacting its overall sensory profile, you get 1 point.

Answer

Chilling: Riesling is a variety with pronounced primary aromas, so producers should chill the grapes to prevent oxidation, which can degrade the grape’s delicate aroma.

Sorting: For premium wine production, unripe or diseased berries can negatively impact the final wine. Therefore, producers sort berries by hand or use optical sorting machines if costs allow. However, if sorting has already been done during harvesting, additional sorting may be minimal.

Destemming: The tannins present in stems are undesirable in premium white Riesling wines, so destemming is typically carried out to prevent tannin extraction.

Crushing: Since Riesling is a white wine, fermentation is conducted with the juice, making crushing a standard practice. To avoid breaking the seeds, which can release bitter tannins, gentle crushing is necessary.

Grading Criteria

• Chilling
  • For explaining that Riesling is a variety with pronounced primary aromas, you get 1 point.
  • For pointing out that producers chill the grapes to prevent oxidation, you get 1 point.
  • For explaining that chilling the grapes can degrade the grape’s delicate aroma, you get 1 point.
• Sorting
  • For explaining that in premium wine production, unripe or diseased berries can negatively impact the final wine, you get 1 point.
  • For pointing out that producers sort berries by hand or use optical sorting machines if costs allow, you get 1 point.
  • For explaining that if sorting has already been done during harvesting, additional sorting may be minimal, you get 1 point.
• Desteming
  • For explaining that the tannins present in stems are undesirable in premium white Riesling wines, you get 1 point.
  • For pointing out that destemming is typically carried out, you get 1 point.
  • For explaining that this prevents tannin extraction, you get 1 point.
• Crushing
  • For explaining that Riesling is a white wine, so fermentation is conducted with the juice, you get 1 point.
  • For pointing out that crushing is a standard practice for this reason, you get 1 point.
  • For explaining that bitter tannins are undesirable in premium white Riesling, you get 1 point.
  • For explaining that if seeds are broken, bitter tannins are released, you get 1 point.
  • For pointing out that gentle crushing is necessary to avoid breaking the seeds, you get 1 point.

Answer

The advantages of a pneumatic press include its ability to process a large volume of grapes at once. It can be programmed to apply different levels of pressure, allowing winemakers to extract various blending components as needed. Additionally, it can be flushed with inert gas before use, protecting the juice or wine from oxidation.

However, the disadvantage of a pneumatic press is its high initial cost, making it a viable option primarily for larger wineries with sufficient financial resources.

The advantages of a basket press lie in its gentle pressing, which some winemakers believe results in a softer extraction. It also requires a lower initial investment compared to a pneumatic press.

On the other hand, the disadvantages of a basket press include higher operational costs due to the need for frequent monitoring. It also has a limited capacity per pressing and cannot be flushed with inert gas, leaving the juice or wine exposed to oxidation.

Grading Criteria

• The advantages of a pneumatic press
  • For pointing out that a pneumatic press can process a large volume of grapes at once, you get 1 point.
  • For explaining that a pneumatic press can be programmed to apply different levels of pressure, you get 1 point.
  • For explaining that this allows winemakers to extract various blending components as needed, you get 1 point.
  • For pointing out that a pneumatic press can be flushed with inert gas before use, you get 1 point.
  • For explaining that this protects the juice or wine from oxidation, you get 1 point.
• The disadvantages of a pneumatic press
  • For pointing out that one disadvantage of a pneumatic press is its high initial cost, you get 1 point.
  • For explaining that this makes it a viable option primarily for larger wineries with sufficient financial resources, you get 1 point.
• The advantages of a basket press
  • For pointing out that some winemakers believe a basket press can extract softer tannins and flavors, you get 1 point.
  • For explaining that it also requires a lower initial investment compared to a pneumatic press, you get 1 point.
• The disadvantages of a pneumatic press
  • For pointing out that a basket press has higher operational costs, you get 1 point.
  • For explaining that this is due to the need for frequent monitoring, you get 1 point.
  • For pointing out that a basket press has a limited capacity per pressing, you get 1 point.
  • For pointing out that a basket press cannot be flushed with inert gas, you get 1 point.
  • For explaining that this leaves the juice or wine exposed to oxidation, you get 1 point.

Answer

To enrich sugar content in must, producers use various methods, including Chaptalisation, which involves adding dry sugar, grape must, concentrated grape must, or rectified concentrated grape must (RCGM). RCGM is commonly used because it does not introduce additional aromas or flavors. However, Chaptalisation is regulated within the EU and is only permitted in cooler regions under specific limits. A drawback of this method is that it increases alcohol but does not enhance flavor concentration, potentially leading to an unbalanced wine.

Another approach to increasing sugar concentration is removing water from the must through reverse osmosis or vacuum evaporation. These methods effectively concentrate sugar but require expensive equipment, making them more suitable for high-volume or premium wine production. Cryoextraction, where grapes are frozen and ice is removed, is a lower-cost alternative. However, the concentration process results in a smaller volume of wine available for sale.

Grading Criteria

• Chaptalisation
  • For pointing out that Chaptalization is a method used to increase sugar content, you get 1 point.
  • For explaining that in Chaptalization, the winemaker adds dry sugar, grape must, concentrated grape must, or rectified concentrated grape must (RCGM), you get 1 point.
  • For pointing out that RCGM is commonly used in Chaptalization, you get 1 point.
  • For explaining that RCGM is preferred because it does not introduce additional aromas or flavors, you get 1 point.
  • For pointing out that one disadvantage of Chaptalization is that it is regulated within the EU and only permitted in cooler regions under specific limits, you get 1 point.
  • For pointing out that Chaptalization increases alcohol but does not enhance flavor concentration, you get 1 point.
  • For explaining that this can lead to an unbalanced wine, you get 1 point.
• Removing water
  • For pointing out that removing water from the must is another method to increase sugar concentration, you get 1 point.
  • For explaining that producers use reverse osmosis or vacuum evaporation to remove water, you get 1 point.
  • For pointing out that one disadvantage is that this method requires expensive equipment, you get 1 point.
• Cryoextraction
  • For pointing out that cryoextraction is another method used to increase sugar concentration, you get 1 point.
  • For explaining that in cryoextraction, grapes are frozen and ice is removed, you get 1 point.
  • For pointing out that cryoextraction is a lower-cost alternative compared to other methods, you get 1 point.
  • For pointing out that one disadvantage is that the concentration process results in a smaller volume of wine available for sale, you get 1 point.

Answer

To acidify must, winemakers typically add tartaric acid, as it is the most stable and widely accepted option. Malic acid and lactic acid may also be used in certain cases. However, malic acid can undergo malolactic fermentation, reducing acidity, while lactic acid provides a softer taste profile. Citric acid is another option but is not permitted in the EU for acidification.

Grading Criteria

• For pointing out that adding tartaric acid is a method of acidification, you get 1 point.
• For explaining that tartaric acid is the most stable and widely accepted option for acidification, you get 1 point.
• For pointing out that adding malic acid is another option for acidifying must, you get 1 point.
• For explaining that malic acid can undergo malolactic fermentation, which reduces acidity, you get 1 point.
• For pointing out that adding lactic acid is another option for acidifying must, you get 1 point.
• For explaining that lactic acid provides a softer taste profile, you get 1 point.
• For pointing out that adding citric acid is another option for acidifying must, you get 1 point.
• For explaining that citric acid is not permitted for acidification in the EU, you get 1 point.

Answer

The main advantage of using ambient yeast is its ability to enhance complexity by allowing multiple yeast species to produce a diverse range of aroma compounds. Because the yeast population in a must can be unique to a specific place or region, ambient yeast helps create a distinctive house style that reflects the terroir. This can also serve as a marketing advantage, as wines made with wild fermentation are often perceived as more authentic and expressive of their origin. Additionally, ambient yeast incurs no extra cost, making it a budget-friendly option for producers.

However, fermentation may start slowly, increasing the risk of volatile acidity, spoilage organisms like Brettanomyces, and off-flavors. It may also take longer to reach dryness, which is impractical for high-volume wineries and raises the risk of stuck fermentation, leaving the wine vulnerable to spoilage. Additionally, consistency cannot be guaranteed, posing a challenge for producers managing large volumes or multiple vintages.

On the other hand, cultured yeast ensures a fast, reliable fermentation to dryness and produces low levels of volatile acidity, decreasing the risk of volatile acidity and spoilage organisms. It also provides consistency across vintages, and with various strains available, winemakers can influence the style of the wine.

The downside of using cultured yeast is the additional cost, as producers must purchase commercial strains. Furthermore, it can lead to a more uniform expression in wine, potentially reducing the individuality and distinctiveness that comes from wild fermentations.

Grading Criteria

• The advantage of ambient yeast
  • For pointing out that ambient yeast enhances complexity, you get 1 point.
  • For explaining that this is because multiple yeast species produce a diverse range of aroma compounds, you get 1 point.
  • For pointing out that ambient yeast contributes to a unique house style that reflects the terroir, you get 1 point.
  • For explaining that this is because the yeast population in a must can be unique to a specific place or region, you get 1 point.
  • For pointing out that fermenting with ambient yeast can also be a marketing advantage, you get 1 point.
  • For explaining that this is because wines made with wild fermentation are often perceived as more authentic and expressive of their origin, you get 1 point.
  • For pointing out that ambient yeast incurs no additional cost, you get 1 point.
• The disadvantage of ambient yeast
  • For pointing out that fermentation may start slowly, you get 1 point.
  • For explaining that this increases the risk of volatile acidity, spoilage organisms like Brettanomyces, and off-flavors, you get 1 point.
  • For pointing out that it may take longer to reach dryness, you get 1 point.
  • For explaining that this is impractical for high-volume wineries and raises the risk of stuck fermentation, leaving the wine vulnerable to spoilage, you get 1 point.
  • For pointing out that consistency cannot be guaranteed, you get 1 point.
  • For explaining that this poses a challenge for producers managing large volumes or multiple vintages, you get 1 point.
• The advantage of cultured yeast
  • For pointing out that cultured yeast ensures a fast, reliable fermentation to dryness, you get 1 point.
  • For pointing out that cultured yeast produces low levels of volatile acidity, you get 1 point.
  • For explaining that this decreases the risk of volatile acidity and spoilage organisms, you get 1 point.
  • For pointing out that cultured yeast provides consistency across vintages, you get 1 point.
  • For pointing out that winemakers can influence the style of the wine by selecting cultured yeast, you get 1 point.
  • For explaining that this is because a wide variety of strains are available, you get 1 point.
• The disadvantage of cultured yeast
  • For pointing out that cultured yeast incurs an additional cost, you get 1 point.
  • For explaining that this is because producers must purchase commercial strains, you get 1 point.
  • For pointing out that cultured yeast can lead to a more uniform expression in wine, you get 1 point.
  • For explaining that this reduces the individuality and distinctiveness associated with wild fermentations, you get 1 point.

Answer

Temperature: To achieve the firm tannins and deep color characteristic of premium Cabernet Sauvignon, fermentation needs to take place at high temperatures, typically between 26 to 32°C (79–90°F). This promotes the maximum extraction of tannins and anthocyanins from the grape skins, resulting in a more structured and intensely colored wine.

Fermentation Vessels: Large oak vessels are preferred for fermentation as they allow for a slight, controlled oxidation, which can enhance the wine’s complexity and tannin integration. Small wooden barrels are generally not suitable for red wine fermentation, as they make cap management difficult. For this reason, large oak vats are the ideal choice when fermenting Cabernet Sauvignon.

Grading Criteria

• Temperature
  • For explaining that premium Cabernet Sauvignon must develop firm tannins and deep color, you get 1 point.
  • For pointing out that fermentation needs to occur at high temperatures, typically between 26–32°C (79–90°F), you get 1 point.
  • For explaining that high fermentation temperatures promote maximum extraction of tannins and anthocyanins from the grape skins, you get 1 point.
  • For explaining that this results in a more structured and intensely colored wine, you get 1 point.
• Fermentation Vessels
  • For pointing out that large oak vessels are preferred for fermentation, you get 1 point.
  • For explaining that this allows for slight, controlled oxidation, you get 1 point.
  • For explaining that controlled oxidation enhances complexity and helps integrate tannins, you get 1 point.
  • For pointing out that small wooden barrels are generally not suitable for red wine fermentation, you get 1 point.
  • For explaining that small barrels make cap management more difficult, you get 1 point.

Answer

In red wines, malolactic conversion slightly reduces color intensity, making the wine appear paler. It also plays an important role in stability. When it occurs during or after fermentation, it helps prevent unwanted fermentation later, such as in the bottle. However, if the wine has a high pH, the slight increase in pH that results from malolactic conversion can make it more susceptible to spoilage organisms. Acidity decreases because malic acid, which has a sharp and strong acidity, is converted into lactic acid, which is softer and less acidic. This transformation influences the overall balance of the wine, making it rounder and smoother.

Aroma is also affected, especially in white wines. The process produces diacetyl, a compound that gives buttery notes, which is particularly noticeable in varieties like Chardonnay. However, this comes at the cost of some fruity aromas, which tend to diminish after malolactic conversion. For this reason, winemakers carefully consider whether to allow the process to occur, depending on the style of wine they aim to produce.

Grading Criteria

• Color
  • For pointing out that malolactic conversion slightly reduces color intensity, making the wine appear paler, you get 1 point.
• Stability
  • For pointing out that malolactic conversion enhances wine stability, you get 1 point.
  • For explaining that this prevents unwanted fermentation later, such as in the bottle, you get 1 point.
• Acidity
  • For pointing out that malolactic conversion increases pH, you get 1 point.
  • For explaining that this makes the wine more susceptible to spoilage organisms, you get 1 point.
  • For explaining that acidity decreases by malolactic conversion, you get 1 point.
  • For explaining that this is because malic acid, which is sharp and strong, is converted into lactic acid, which is softer and less acidic, you get 1 point.
  • For pointing out that this conversion makes the wine rounder and smoother, you get 1 point.
• Aroma
  • For pointing out that malolactic conversion gives buttery notes, you get 1 point.
  • For explaining that this is caused by diacetyl, a byproduct of malolactic conversion, you get 1 point.
  • For pointing out that this process reduces some fruity aromas, you get 1 point.