SWEET WINE VINIFICATION

Question 1

Which compounds are in a higher amount present in the must due to botrytis grapes?

Answer 1

Laccase
Pectinase
Glycosidases

Question 2

Which types of acid are extremely decreased in botrytis must?

Answer 2

Malic acid
Lactic acid

Question 3

Why is N decreased in botrytis must?

Answer 3

Because the fungus eats proteins and amino acids

Question 4

What is the consequence of elevated levels of glucans in the must?

Answer 4

Filter and clarification problems

Question 5

What is the result of high levels of botryticine?

Answer 5

Elevated glucose
Elevated acetic acid

Question 6

Why does botrytis sweet wine need more SO2 for protection?

Answer 6

Due to higher amount of carbonyl groups, acetaldehyde’s etc that bind SO2

Question 7

At which moment in the season wil botrytis strike?

Answer 7

Highest rist from versaison onwards.
Botrytis is weak pathogen, it will attack fully ripe, high sugar, thin skinned grapes.

Question 8

Explain when cryoestraction technique will be used

Answer 8

When the botrytis is all over the vineyard and there was unexpected rain and no good weather in the upcoming days that will dry the grapes. This saves your harvest.

Question 9

What is the explanation for elevated levels of acetic acid bacteria in botrytis must?

Answer 9

The yeast are under an elevated amount of osmotic stress due to extreme high levels of sugar in the must. That will cause a higher production of glycerol, which produces more acetic acid bacteria

Question 10

What is the average amount of residual sugar in botrytis must?

Answer 10

300-400 g/l

Question 11

What is the average amount of YAN in must. Dry wines vs. botrytis wines

Answer 11

Dry: 182 mg/l
Botrytis: 94 mg/l

Question 12

What is the optimal range of YAN in fermenting must?

Answer 12

Between 190-200 mg/l

Question 13

Which non sac. yeast is known for low VA production and resistance to high sugar levels in the must?

Answer 13

Torulaspora Delbrueckii

Question 14

What is the ideal temperature for AF in case of botrytis must?

Answer 14

Around 25C. You need enough warmth for the yeast to be able to do his job. But not higher due to elevated levels of VA production.

Question 15

Why do we wait with SO2 addition after AF?

Answer 15

Yeast appear to be dead at the end of AF, but in reality there is still enzymatic reaction inside that will bind SO2 when added. This decreases with 8-10 days

Question 16

What can be done to keep levels of SO2 as low as possible?

Answer 16

Add Thiamine at start of AF to reduce stress of the yeast.
Use low S02 producing yeast strain.