Wine Faults

Question 1

Two major possibilities for defects

Answer 1

1. From the maturation of the berries
2. Alterations associated with fungal diseases

Question 2

What is IBMP and what is the odor and where does it come from?

Answer 2

3-isobutyl-2-methoxypyrazine and the odor is herbaceous and green bell pepper (from maturation of the berries)

Question 3

What is Geosmin and what is the odor and where does it come from?

Answer 3

A defect causing an odor of earthy and beetroot. It comes from moldy grapes (fungal disease)

Question 4

What is IPMP and what is the odor and where does it come from?

Answer 4

isopropyl methoxypyrazine, it causes an odor of wet earth and aspargus and comes from maturation of berries

Question 5

What is Ottenone, what is the odor and where does it come from?

Answer 5

A defect causing an odor of wet mushroom and it comes from fungal diseases.

Question 6

What is an herbaceous note found from crushing

Answer 6

Hexanol

Question 7

How can we prevent the formation of hexanol? (3)

Answer 7

1. We can collect grapes at maturity
2. Avoid bad handling of grapes
3. Rapidly obtain a clean must

Question 8

5 things we can do to reduce herbaceous notes

Answer 8

1. Clarification is the best method
2. caseinate (milk proteins)
3. PVPP Bentonite
4. Mixture of protein gels and glues
5. Microoxygenation in both reds and whites

Question 9

How to prevent geosmin (4)

Answer 9

Appropriate fight against botrytis and fungal diseases
Racking
Clarification
Favor curative treatments in the vineyard

Question 10

4 main defects tied to fermatation

Answer 10

1. Acetic acid
2. Ethyl Acetate
3. Acetaldehyde
4. Diacetyl

Question 11

Acetic Acid odor

Answer 11

Vinegar, pungent

Question 12

Ethyl Acetate odor

Answer 12

Sour and turning sour

Question 13

Acetaldehyde ordor

Answer 13

Rotten apple

Question 14

Diacetyl odor

Answer 14

Lactic, butter

Question 15

Possible causes of ethyl acetate

Answer 15

It is produced during AF, can be due to the use of indigenous yeasts as well as acetic acid bacteria during aging and storing

Question 16

Possible causes of Acetaldehyde

Answer 16

Oxidation of ethanol, Yeast metabolism, Bacteria metabolism, direct chemical oxidation

Question 17

How to prevent acetaldehyde (4)

Answer 17

1. choice of yeast strain
2. Avoid undesired oxidation
3. management of micro-oxygenation
4. Management of SO2

Question 18

How do we get acetic acid? (2)

Answer 18

1. Acidic rot and contamination of indigenous yeasts
2. production during AF and partly from LAB

Question 19

How to prevent Acetic acid

Answer 19

Good hygiene and removal of clusters with acidic rot

Question 20

Diacetyl is a defect associated with…

Answer 20

Bacterial metabolism

Question 21

How to we mange Diacetyl? (2)

Answer 21

1. Choice of LAB strain
2. Choice of when to do MLF

Question 22

5 ways to get a fruited wine post MLF

Answer 22

• MLF inoculated with strong biomass (direct inoculation), citric strains
• Rapid MLF (22-23°C)
• Filter at the end of MLF to eliminate bacteria
• Re-add lees of Chardonnay
• Fining on lees, which absorb diacetyl – not more than 2 weeks

Question 23

2 ways to get a buttery wine post MLF

Answer 23

1. MLF at lower temp
2. Filtration starting from the end of MLF, less fining on lees

Question 24

3 big families of possible defects

Answer 24

1. The “Great Classics” primary products of metabolism of yeast and bacteria
2. The defects associated with bacterial metabolism
3. Alterations caused by sulphured compounds

Question 25

5 typical lactic fermentative aromas

Answer 25

1. Diacetyl
2. Ethyl Lactate
3. Acetone
4. Butandiole
5. Pentandione

Question 26

Ethyl acetate aroma

Answer 26

Sour/acidic milk

Question 27

Acetone aroma

Answer 27

Butter, caramel

Question 28

Butandiole aroma

Answer 28

Vegetal

Question 29

Pentandione aroma

Answer 29

Butter caramel

Question 30

Mousy aroma, where it comes from and how to prevent it

Answer 30

Lactobacilli are the main causes of the formation (but also Brettanomyces), 2 precursors: ethanol and lysine. Elimination via tartaric acid precipitations

Avoid the appearance of this defect by paying close attention to insufficient sulphite levels, avoid proliferation of lactobacilli (bacterial inoculation, preventative use of lysozymes)

Question 31

Alterations caused by sulpur compounds, 3 main compounds

Answer 31

1. Ethanethiol
2. Methanethiol
3. Hydrogen Sulphide

Question 32

Hydrogen Sulphide aroma and formation

Answer 32

Rotten eggs and is formed from the complexity of yeast metabolism during AF and Autolysis

Question 33

Ethanethiol aroma and formation

Answer 33

Onion, garlic, natural gas
Formed from Ethanol + H2S

Question 34

Methanethiol aroma and formation

Answer 34

Cauliflower and potato and is formed with increasing turbidity (NTU)

Question 35

Light defect, what is it’s aroma and what causes it

Answer 35

Light defect (DMDS) has an aroma of Cabbage and it comes from light and its photochemical effect on the wine in bottle as it ages.

Question 36

Differences between TCA, TBA, and TeCA

Answer 36

All of them give off a mouldy aroma, but where they come from changes. TCA comes from the cork itself, or environment, while TBA and TeCA usually come from the winery environment. TeCA can be caused from fungicide activity on wood. This is why at the winery we would also use heat treated pallets.