WSET Diploma D1 Exercises (Finishing and Packaging)

Answer

Fining agents carry an opposite charge to the suspended particles in wine. They chemically bind to colloids, forming larger aggregates that settle as sediment, which can then be removed through racking. Because fining agents interact chemically with the wine, they selectively remove specific compounds, such as excessive tannins or proteins that could cause cloudiness.

While fining relies on chemical reactions to precipitate unwanted substances, filtering is a mechanical process that physically removes suspended solids by passing the wine through a filtration medium. Therefore, fining is particularly useful for eliminating unstable colloids that are too small to be captured by filtration.

Grading Criteria

• How to work
  • For explaining that fining agents carry an opposite charge to suspended particles in wine, you get 1 point.
  • For explaining that fining agents chemically bind to colloids, you get 1 point.
  • For explaining that this forms larger aggregates that settle as sediment, you get 1 point.
  • For explaining that these sediments can then be removed through racking, you get 1 point.
  • For explaining that fining agents selectively remove specific compounds, you get 1 point.
  • For explaining that this is because fining agents chemically interact with the wine, you get 1 point.
• Distinguishing from filtering
  • For explaining that filtration is a mechanical process that physically removes suspended solids, you get 1 point.
  • For explaining that filtration removes solids by passing the wine through a filtration medium, you get 1 point.
  • For comparing that fining relies on chemical reactions to precipitate unwanted substances, you get 1 point.
  • For explaining that fining is particularly useful for eliminating unstable colloids that are too small to be captured by filtration, you get 1 point.

Answer

Bentonite is commonly used to remove unstable proteins and colloidal coloring matter from wine. It carries an opposite charge and absorbs these compounds through an ion exchange process. However, its use can result in some color loss in red wines, making them appear paler. Additionally, bentonite creates a large amount of sediment, leading to wine loss during racking.

Egg white is primarily used to remove unstable tannins and phenolic compounds, helping to clarify wine while maintaining its delicate flavors. It is commonly used in premium red wines because of its gentle effect on the wine. Since it is an allergen, wines treated with egg white must be labeled accordingly in the EU and other regions if the concentration exceeds a specified limit. Additionally, wines fined with egg white are not suitable for vegan consumers.

Gelatin is used to remove unstable tannins and phenolic compounds, reducing bitterness and astringency in red wine and preventing browning in white wine. However, excessive use can strip the wine of its flavors and may cause protein haze. To prevent this, it should be added in the smallest effective amount. Since it is derived from animal protein, gelatin is not suitable for vegan wines.

Charcoal is used to eliminate browning pigments and unwanted off-odors in wine. However, it has the potential to remove desirable aromas as well, so its application must be carefully controlled. A common approach is to treat only a portion of the affected wine and then blend it with the rest to minimize the impact on aroma and flavor.

Grading Criteria

• Bentonite
  • For pointing out that bentonite is commonly used to remove unstable proteins and colloidal coloring matter from wine, you get 1 point.
  • For explaining that bentonite carries an opposite charge and absorbs these compounds through an ion exchange process, you get 1 point.
  • For highlighting the disadvantage that its use can cause some color loss in red wines, making them appear paler, you get 1 point.
  • For pointing out that bentonite creates a large amount of sediment, leading to wine loss during racking, you get 1 point.
• Egg white
  • For pointing out that egg white is primarily used to remove unstable tannins and phenolic compounds, you get 1 point.
  • For explaining that it helps clarify wine while preserving delicate flavors, you get 1 point.
  • For explaining that it is commonly used in premium red wines because of its gentle effect, you get 1 point.
  • For highlighting the disadvantage that egg white is an allergen, you get 1 point.
  • For explaining that wines treated with egg white must be labeled accordingly in the EU and other regions if the concentration exceeds a specified limit, you get 1 point.
  • For pointing out that wines fined with egg white are not suitable for vegan consumers, you get 1 point.
• Gelatine
  • For pointing out that gelatin is used to remove unstable tannins and phenolic compounds, you get 1 point.
  • For explaining that this reduces bitterness and astringency in red wine, you get 1 point.
  • For explaining that this prevents browning in white wine, you get 1 point.
  • For highlighting the disadvantage that excessive use can strip the wine of its flavors and may cause protein haze, you get 1 point.
  • For explaining that because of this, gelatin should be added in the smallest effective amount, you get 1 point.
  • For pointing out that gelatin is not suitable for vegan wines since it is derived from animal protein, you get 1 point.
• Charcoal
  • For pointing out that charcoal is used to eliminate browning pigments and unwanted off-odors in wine, you get 1 point.
  • For highlighting the disadvantage that it can also remove desirable aromas, you get 1 point.
  • For explaining that its application must be carefully controlled, you get 1 point.
  • For explaining that a common approach is to treat only a portion of the affected wine and then blend it with the rest to minimize the impact on aroma and flavor, you get 1 point.

Answer

Diatomaceous earth is depth filtration; this capture particles within the depth of the filtering material, making them less prone to clogging. However, they do not provide absolute filtration, meaning some particles may still pass through. Diatomaceous earth is an inert filtering medium, so it has minimal impact on the wine’s characteristics. It also has a relatively low running cost. However, the initial investment in equipment is high, and the disposal of used diatomaceous earth incurs additional costs.

Sheet filters are also depth filtration; this capture particles within the depth of the filtering material, making them less prone to clogging. However, they do not provide absolute filtration, meaning some particles may still pass through. Sheet filters have a lower running cost, but the initial cost of the filter frame is significant. Additionally, they require skilled personnel to operate efficiently.

Membrane filters are surface filtration, blocking particles larger than their pore size, making them an absolute filtration method. Due to their small pores, they are prone to clogging, requiring pre-filtration. Although the initial cost is low, frequent filter replacements are necessary, resulting in high ongoing costs.

Cross-flow filters are surface filtration, blocking particles larger than their pore size, making them an absolute filtration method. Cross-flow filters allow wine to pass through while continuously cleaning the filter surface, preventing clogging. They efficiently process wines with high particle loads or lees and do not require replacement sheets or cartridges, reducing waste and maintenance costs. However, the equipment is expensive, making it more suitable for large or well-funded wineries.

Grading Criteria

• Diatomaceous earth
  • For pointing out that diatomaceous earth is a depth filtration method, you get 1 point.
  • For explaining that it captures particles within the depth of the filtering material, you get 1 point.
  • For highlighting the advantage that this makes it less prone to clogging, you get 1 point.
  • For pointing out the disadvantage that it does not provide absolute filtration, meaning some particles may still pass through, you get 1 point.
  • For highlighting the advantage that diatomaceous earth has minimal impact on the wine’s characteristics, you get 1 point.
  • For explaining that this is because diatomaceous earth is an inert filtering medium, you get 1 point.
  • For pointing out the disadvantage that the initial investment in equipment is high, you get 1 point.
  • For highlighting the disadvantage that disposing of used diatomaceous earth incurs additional costs, you get 1 point.
• Sheet filters
  • For pointing out that sheet filters use depth filtration, you get 1 point.
  • For explaining that they capture particles within the depth of the filtering material, you get 1 point.
  • For highlighting the advantage that this makes them less prone to clogging, you get 1 point.
  • For pointing out the disadvantage that they do not provide absolute filtration, meaning some particles may still pass through, you get 1 point.
  • For highlighting the advantage that they have lower running costs, you get 1 point.
  • For pointing out the disadvantage that the initial cost of the filter frame is significant, you get 1 point.
  • For highlighting the disadvantage that they require skilled personnel to operate efficiently, you get 1 point.
• Membrane filters
  • For pointing out that membrane filters use surface filtration, you get 1 point.
  • For explaining that they block particles larger than their pore size, you get 1 point.
  • For highlighting the advantage that this makes them an absolute filtration method, you get 1 point.
  • For pointing out the disadvantage that they are prone to clogging due to their small pores, you get 1 point.
  • For explaining that they require pre-filtration to prevent clogging, you get 1 point.
  • For highlighting the advantage that the initial cost is low, you get 1 point.
  • For pointing out the disadvantage that frequent filter replacements are necessary, resulting in high ongoing costs, you get 1 point.
• Cross-flow filters
  • For pointing out that cross-flow filters use surface filtration, you get 1 point.
  • For explaining that they block particles larger than their pore size, you get 1 point.
  • For highlighting the advantage that this makes them an absolute filtration method, you get 1 point.
  • For highlighting the advantage that cross-flow filters do not clog, you get 1 point.
  • For explaining that this is because they allow wine to pass through while continuously cleaning the filter surface, you get 1 point.
  • For highlighting the advantage that they reduce waste and maintenance costs, you get 1 point.
  • For explaining that this is because they efficiently process wines with high particle loads or lees and do not require replacement sheets or cartridges, you get 1 point.
  • For pointing out the disadvantage that the equipment is expensive, you get 1 point.

Answer

In cold stabilization, wine is chilled to -4 degrees for about eight days, allowing tartrate crystals to form before bottling so they can be filtered out. This method requires specialized equipment and incurs high energy costs. Additionally, it only removes potassium bitartrate and is ineffective against calcium tartrate.

Electrodialysis uses a charged membrane to selectively remove ions. Although this process uses less energy and is faster, it requires a significant initial investment.

Carboxymethylcellulose (CMC) prevents tartrates from growing large enough to be visible. However, it is unsuitable for red wines because it reacts with tannins, leading to haze formation.

Grading Criteria

• Cold Stabilisation
  • For explaining that in cold stabilization, wine is chilled to -4°C for about eight days, you get 1 point.
  • For explaining that this allows tartrate crystals to form before bottling, you get 1 point.
  • For highlighting the disadvantage that this method requires specialized equipment and incurs high energy costs, you get 1 point.
  • For pointing out the disadvantage that it only removes potassium bitartrate and is ineffective against calcium tartrate, you get 1 point.
• Electrodialysis
  • For explaining that electrodialysis uses a charged membrane to selectively remove ions, you get 1 point.
  • For highlighting the disadvantage that it requires a significant initial investment, you get 1 point.
• Carboxymethylcellulose
  • For explaining that carboxymethylcellulose prevents tartrates from growing large enough to be visible, you get 1 point.
  • For highlighting the disadvantage that it is unsuitable for red wine, you get 1 point.
  • For explaining that this is because it reacts with tannins, leading to haze formation, you get 1 point.

Answer

Cloudiness and hazes in wine present a visual problem, making the wine appear unhealthy or flawed. In some cases, re-fermentation may also occur. To prevent these issues, producers filter out unstable proteins and remove bacteria and yeast through proper stabilization. Maintaining strict hygiene in the winery and conducting chemical analysis before bottling are also crucial steps.

If severe reduction occurs, the wine develops sulfur-like odors ranging from onion to rotten eggs, which are considered off-flavors. These compounds are often produced when yeast is under stress due to a lack of nutrients such as nitrogen and oxygen during fermentation. To prevent this, winemakers must provide sufficient nutrients and carefully control fermentation temperature. Reduction can also develop in bottled wine, especially when sealed with screw caps due to the extremely low oxygen ingress, so managing sulfur dioxide additions is essential to avoid this fault.

Light strike occurs when ultraviolet and certain wavelengths of visible light react with wine components, forming sulfides that create undesirable odors. To prevent this, producers typically use dark green or brown glass bottles and store wines in conditions that minimize light exposure.

Wines affected by Brettanomyces develop a range of off-aromas, including animal, spicy, or farmyard notes. While some consider these aromas to add complexity in small amounts, excessive Brettanomyces activity is a fault that overwhelms fruit flavors and alters the wine’s balance. To prevent its growth, winemakers maintain sufficient levels of sulfur dioxide and add it promptly after fermentation, since low pH inhibits its growth. Maintaining winery cleanliness is also essential to minimize bacterial contamination and spoilage.

Grading Criteria

• Cloudiness and hazes
  • Affect
    • For pointing out that cloudiness and hazes in wine present a visual problem, you get 1 point.
    • For explaining that this makes the wine appear unhealthy or flawed, you get 1 point.
    • For pointing out that re-fermentation may also occur in some cases, you get 1 point.
  • How to avoide
    • For explaining that producers filter out unstable proteins and remove bacteria and yeast through proper stabilization, you get 1 point.
    • For pointing out that maintaining strict hygiene in the winery is an essential step to prevent faults, you get 1 point.
    • For pointing out that conducting chemical analysis before bottling is also crucial to avoid faults, you get 1 point.
• Reduction
  • Affect
    • For pointing out that severe reduction causes sulfur-like odors ranging from onion to rotten eggs, you get 1 point.
    • For explaining that these odors are considered off-flavors, you get 1 point.
  • How to avoid
    • For explaining that these compounds are often produced when yeast is under stress, you get 1 point.
    • For explaining that this stress caused by a lack of nutrients such as nitrogen and oxygen during fermentation, you get 1 point.
    • For pointing out that winemakers must provide sufficient nutrients and carefully control fermentation temperature to prevent reduction, you get 1 point.
    • For explaining that reduction can also develop in bottled wine, especially when sealed with screw caps due to the extremely low oxygen ingress, you get 1 point.
    • For pointing out that managing sulfur dioxide additions is essential to avoid this fault, you get 1 point.
• Light Strike
  • Affect
    • For pointing out that light strike causes sulfides to form, resulting in undesirable odors, you get 1 point.
    • For explaining that light strike occurs when ultraviolet and certain wavelengths of visible light react with wine components, you get 1 point.
  • How to avoid
    • For pointing out that producers typically use dark green or brown glass bottles and store wines in controlled conditions to prevent light strike, you get 1 point.
    • For explaining that these bottles minimize light exposure, you get 1 point.
• Brettanomyces
  • Affect
    • For pointing out that Brettanomyces produces a range of off-aromas, you get 1 point.
    • For listing examples of off-aromas such as animal, spicy, or farmyard notes, you get 1 point.
    • For pointing out that excessive Brettanomyces activity overwhelms fruit flavors and alters the wine’s balance, you get 1 point.
    • For explaining that some consider these aromas to add complexity in small amounts, you get 1 point.
  • How to avoid
    • For pointing out that winemakers maintain sufficient levels of sulfur dioxide and add it promptly after fermentation to prevent the growth of Brettanomyces, you get 1 point.
    • For explaining that low pH inhibits its growth, you get 1 point.
    • For pointing out that maintaining winery cleanliness is essential to minimize bacterial contamination and spoilage, you get 1 point.

Answer

Glass is well-suited for premium red wine. As an inert material, it does not affect the wine’s flavor or composition. Additionally, it is also highly impermeable to oxygen, preventing unwanted oxidation and allowing for long-term aging.

However, there are some drawbacks. Glass is heavy and relatively fragile, adding to transportation costs. Its rigidity also means that once a bottle is partially consumed, air enters the headspace, causing rapid oxidation. Therefore, wine should be consumed immediately after opening. Clear glass bottles pose another risk, as they can cause light strike when exposed to fluorescent or natural light, resulting in sulfur-related off-aromas. Green or brown bottles offer better protection against this issue.

On the other hand, bag-in-box is not suitable because it does not provide sufficient protection against oxygen ingress. With a shelf life of up to one year, it is not ideal for premium wines, which are typically aged for decades.

Grading Criteria

• Glass
  • For concluding that glass bottles are suitable for premium wine, you get 1 point.
  • For pointing out that glass is made from an inert material, you get 1 point.
  • For explaining that this means it does not affect the wine’s flavor or composition, you get 1 point.
  • For pointing out that glass is also highly impermeable to oxygen, you get 1 point.
  • For explaining that this prevents unwanted oxidation and allows for long-term aging, you get 1 point.
  • For highlighting the drawback that glass is heavy and relatively fragile, you get 1 point.
  • For explaining that this results in high transportation costs, you get 1 point.
  • For pointing out that its rigidity means that once a bottle is partially consumed, air enters the headspace, causing rapid oxidation, you get 1 point.
  • For explaining the consequence of this, such as the need to consume wine immediately after opening, you get 1 point.
  • For pointing out that clear glass bottles can cause light strike when exposed to fluorescent or natural light, you get 1 point.
  • For explaining that green or brown bottles offer better protection against this issue, you get 1 point.
• Bag-in-box
  • For concluding that bag-in-box is not suitable for premium wine, you get 1 point.
  • For pointing out that bag-in-box does not provide sufficient protection against oxygen ingress, you get 1 point.
  • For explaining that the shelf life of bag-in-box is up to one year, you get 1 point.
  • For explaining that this makes it unsuitable for premium wines, which are typically aged for decades, you get 1 point.

Answer

Natural cork is well-suited for premium red wine due to its strong reputation among consumers. High-quality, longer corks are typically used for premium wines. The slow oxygen ingress through the cork can have a positive effect, helping to develop tertiary aromas and soften tannins through binding.

However, there are some drawbacks. Natural cork can sometimes contain TCA, which taints the wine and creates off-flavors reminiscent of mold and wet cardboard. Additionally, oxygen permeability varies between individual corks, leading to inconsistencies in the aging process. As a result, the same wine sealed with natural cork may age at different rates over the medium to long term.

Synthetic closures, made from plastic, are generally not considered suitable for premium wines. Moulded closures, a type of synthetic closure, offer little protection against oxygen ingress and are therefore unsuitable for aging. However, extruded closures come in various oxygen ingress levels, making some potentially suitable for premium wines. Additionally, plastic closures can cause flavour scalping, where the plastic absorbs certain aroma compounds, potentially diminishing the wine’s flavor intensity—an undesirable effect for premium wines.

Screwcaps eliminate the risk of TCA contamination, ensuring consistent quality. While fully airtight screwcaps are not suitable for bottle aging, some allow limited oxygen ingress, making them a viable option for aging premium wines. Regardless, winemakers using screwcaps must adjust the final wine to have slightly lower SO₂ levels to prevent unpleasant onion-like aromas caused by reduction.

However, consumer acceptance varies by country. In places like Australia and New Zealand, screwcaps are widely accepted, whereas in other markets, they are still associated with inexpensive wines, making it challenging to market premium wines.

Grading Criteria

• Natural cork
  • For pointing out that natural cork is well-suited for premium red wine, you get 1 point.
  • For explaining that this is due to its strong reputation among consumers, you get 1 point.
  • For explaining that high-quality, longer corks are typically used for premium wines, you get 1 point.
  • For pointing out that the slow oxygen ingress through cork can have a positive effect, you get 1 point.
  • For explaining that this helps develop tertiary aromas and soften tannins through binding, you get 1 point.
  • For pointing out that natural cork can sometimes contain TCA, you get 1 point.
  • For explaining that TCA taints the wine and creates off-flavors reminiscent of mold and wet cardboard, you get 1 point.
  • For pointing out that oxygen permeability varies between individual corks, you get 1 point.
  • For explaining that this leads to inconsistencies in the aging process, you get 1 point.
  • For explaining that as a result, the same wine sealed with natural cork may age at different rates over the medium to long term, you get 1 point.
• Synthetic closure
  • For explaining the premise that synthetic closures are made from plastic, you get 1 point.
  • For pointing out that synthetic closures are generally not considered suitable for premium wines, you get 1 point.
  • For pointing out that moulded closures are unsuitable for aging, you get 1 point.
  • For explaining that this is because moulded closures offer little protection against oxygen ingress, you get 1 point.
  • For pointing out that extruded closures are potentially suitable for premium wines, you get 1 point.
  • For explaining that this is because extruded closures have various oxygen ingress levels, you get 1 point.
  • For pointing out that plastic closures can cause flavor scalping, you get 1 point.
  • For explaining that this occurs because plastic absorbs certain aroma compounds, you get 1 point.
  • For explaining that as a result, this can potentially diminish the wine’s flavor intensity, you get 1 point.
• Screwcap
  • For pointing out that screwcaps eliminate the risk of TCA contamination, you get 1 point.
  • For explaining that this is an advantage for ensuring consistent quality, you get 1 point.
  • For pointing out that fully airtight screwcaps are not suitable for bottle aging, you get 1 point.
  • For explaining that some screwcaps allow limited oxygen ingress, you get 1 point.
  • For pointing out that this makes them a viable option for aging premium wines, you get 1 point.
  • For explaining that winemakers using screwcaps must adjust the final wine to have slightly lower SO₂ levels, you get 1 point.
  • For explaining that this prevents unpleasant onion-like aromas caused by reduction, you get 1 point.
  • For pointing out that consumer acceptance varies by country, you get 1 point.
  • For explaining that screwcaps are widely accepted in places like Australia and New Zealand, you get 1 point.
  • For explaining that in other markets, they are still associated with inexpensive wines, you get 1 point.
  • For explaining that this makes it challenging to market premium wines, you get 1 point.

Answer

Bulk transport is a cost-effective method as it allows more wine to be shipped per container compared to bottle transport. To maximize cost efficiency, bulk transport is best suited for high-volume wines, making it a practical option for inexpensive, large-scale production wines. Its high thermal mass helps maintain a stable temperature, preventing oxidation and preserving fresh aromas. Additionally, bulk transport extends a wine’s shelf life, which is especially beneficial for bag-in-box packaging, given its shorter shelf life. However, one concern is that the direct relationship with the producer becomes diluted.

With bottle transport, the producer retains full control over the product, including bottling and labeling. However, high transportation costs, a shorter shelf life, and the risk of damage from high or fluctuating temperatures make it a less viable option for inexpensive, high-volume wine.

Grading Criteria

• Bulk transport
  • For pointing out that bulk transport is a cost-effective method, you get 1 point.
  • For explaining that this is because bulk transport allows more wine to be shipped per container compared to bottle transport, you get 1 point.
  • For pointing out that bulk transport is best suited for high-volume wines to maximize cost efficiency, you get 1 point.
  • For pointing out that its high thermal mass helps maintain a stable temperature, you get 1 point.
  • For explaining that this prevents oxidation and preserves fresh aromas, you get 1 point.
  • For pointing out that bulk transport extends a wine’s shelf life, you get 1 point.
  • For explaining that this is especially beneficial for bag-in-box packaging, you get 1 point.
  • For pointing out that one concern is that the direct relationship with the producer may become diluted, you get 1 point.
• Bottle transport
  • For pointing out that bottle transport allows the producer to retain full control over the product, you get 1 point.
  • For pointing out that bottle transport incurs high transportation costs, you get 1 point.
  • For pointing out that bottle transport results in a shorter shelf life, you get 1 point.
  • For pointing out that bottle transport carries the risk of damage from high or fluctuating temperatures, you get 1 point.
  • For concluding that bottle transport is therefore a less viable option for inexpensive, high-volume wines, you get 1 point.