Viticulture pt. 1

Question 1

What two gases play fundamental roles in wine making?

Answer 1

Oxygen and Sulfur Dioxide

Question 2

Oxygen is generally a threat for what style of wines?

Answer 2

Fresh, fruity wines

Question 3

How can oxygen affect those fresh, fruity styles of wine?

Answer 3

Oxygen can affect different compounds in those fresh, fruity wines leading to either a lose of certain flavors, or the creation of other unwanted flavors

Question 4

What is an example of oxygen affecting compounds in a wine, leading to a loss of flavor?

Answer 4

Thiols are a compound found in Sauvignon Blanc and they break down in the presence of oxygen, which lead to a loss of fruitiness

Question 5

What is an example of oxygen reacting to a compound found in wine, creating an undesired flavor?

Answer 5

Oxygen can create acetaldehyde from oxidizing ethanol, which creates a nutty, bruised apple aroma

Question 6

How does oxygen affect the color of wines?

Answer 6

Makes red wines lighter and white/rose wines darker

Question 7

What are some ways to mitigate oxygen exposure

Answer 7

• avoiding ullage in barrels, tanks, and bottles
• using an inert gas like nitrogen, carbon dioxide and argon to flush oxygen out of vessels, pipes or equipment
• adding/using sulfites
• using impermeable vessels like stainless steel or thick concrete vessels
• cool temperatures can aid in slowing the rate of oxidation as well

Question 8

How can controlled exposure to oxygen be beneficial to wine?

Answer 8

• Oxygen during fermentation is important to keep the yeast healthy
• In the production of some white wines, exposing the must to oxygen is thought to lead to great oxidation stability
• In red wines, oxygen is essential in the reactions between anthocyanins and tannins will lead to greater color stability
• Exposure to oxygen over time leads to more complex flavors and aromas

Question 9

Why is Sulfur Dioxide almost universally used in wine?

Answer 9

It is a great anti-oxidant and anti-microbial properties