17.2 Stopping the Fermentation

Question 1

What is fermentation?

Answer 1

the process by which sugars in the grapes are converted to alcohol by yeast

Question 2

When a fermentation is stopped before it is finished, what is the result in the wine?

Answer 2

stopping this process before all the sugars have been converted results in a wine with residual sugar

Question 3

What are the main advantages of making sweet wine by stopping the fermentation?

Answer 3

• the winemaker has control over the level of sugar in the final wine
• relatively quick, simple, and low risk

Question 4

When the fermentation is stopped earlier, what is the result in the wine?

Answer 4

• higher levels of residual sugar

- lower levels of alcohol

Question 5

Give an example of a wine that is sweet because fermentation was stopped earlier. What is the g/l of RS? What is the abv?

Answer 5

Moscato d’Asti

• 120–130 g/l
• 4.5–6% abv

Question 6

In general, how sweet are the resulting wines?

Answer 6

off-dry to medium-sweet

Question 7

What types of wines are made by stopping the fermentation?

Answer 7

inexpensive or mid-priced wines

Question 8

What are the disadvantages of making sweet wine by stopping the fermentation?

Answer 8

• rare to find the same intensity and/or complexity of the wines produced by concentrating the grape sugars
• tend not to reach outstanding levels of quality

Question 9

What are the most common ways of interrupting the fermentation?

Answer 9

• chilling to below 10°C (50°F) and/or

- adding a high dose of SO2 to inhibit the yeast

Question 10

Describe how sweet wines are made by stopping the fermentation.

Answer 10

• chilled or SO2 added
• racked off sediment
• sterile filtered to ensure fermentation does not start again later