D1 Faults

Question 1

List 9 major faults found in wine today.

Answer 1

1. Cloudiness / hazes;
2. Tartrates;
3. Refermentation in the bottle;
4. Cork taint;
5. Oxidation;
6. Volatile acidity;
7. Reduction;
8. Light strike;
9. Brettanomyces.

Question 2

Give four reasons wine can be cloudy / hazy after bottling.

Answer 2

1. Growth of yeast or bacteria;
2. Failure to filter (or the wine was filtered inadequately);
3. Wrong type of fining agent was used;
4. Wine was over-fined, causing the remaining proteins in the wine to become unstable.

Question 3

Name five ways to avoid cloudiness / haze in a finished wine.

Answer 3

1. Improve hygiene in the winery;
2. Pre-bottling chemical analysis;
3. Proper filtering;
4. Use correct fining agent;
5. Not over-fining.

Question 4

Why are tartrates seen as a fault to some wine drinkers?

Answer 4

Even though tartrates are completely harmless and naturally precipitate out of wine when it is held at a sustained cool temperature, tartrates look like foreign objects in the wine, namely shards of glass or large sugar crystals, which puts off some wine drinkers.

Question 5

If you opened a wine that has a slight prickle or spritz to it which the wine isn’t supposed to have, and the wine is also kind of cloudy, what’s happening to the wine?

Answer 5

It’s refermenting – the winemaker failed to stabilize and clarify/filter the wine adequately.

Question 6

How does cork taint present itself in wine?

Answer 6

• Smells like wet, moldy cardboard;
• Reduces fruit character on the palate;
• Makes a wine’s finish shorter.

Question 7

How does oxidation present itself in wine?

Answer 7

• Wine turns brown prematurely;
• Loss of primary fruit;
• Vinegary smell.

Question 8

Give three main reasons why wines suffer from oxidation in the bottle.

Answer 8

1. Faulty bottling;
2. Poor-quality corks or plastic closures;
3. Keeping wine for too long when it doesn’t have the quality to age.

Question 9

All wines have some level of volatile acidity but excessive amounts give a pungent smell of ____ and/or ____.

Answer 9

Nail polish remover and/or vinegar

Question 10

What causes volatile acidity to become a fault?

Answer 10

• Active acetic acid bacteria;
• Inadequate levels of SO₂;
• Excess exposure to oxygen.

Question 11

Name five ways to avoid volatile acidity from becoming a fault.

Answer 11

1. Sorting fruit to exclude damaged grapes;
2. Meticulous hygiene in the winery;
3. Keeping vessels topped up;
4. Careful racking (to avoid excessive exposure to oxygen);
5. Maintaining adequate SO₂ levels.

Question 12

What are some odors associated with reduction when it’s considered a fault?

Answer 12

• Onion;
• Rotten eggs.

Question 13

What are some odors associated with reduction when it’s not considered a fault?

Answer 13

• Struck match;
• Smoke.

Question 14

What are reductive odors caused by?

Answer 14

1. High levels of volatile, reductive sulfur compounds that are produced by yeast under stress (due to low nitrogen levels) during winemaking;
2. Near-anaerobic environments (no oxygen) during aging in closed vessels, especially during lees aging;
3. Sometimes these odors evolve when wine is closed with the impermeable type of screw cap.

Question 15

Name three ways to avoid reduction in wine.

Answer 15

• Ensure yeast has sufficient nutrients and oxygen during the winemaking process;
• Ensure the must is at an adequate temperature;
• SO₂ may need to be lowered, especially if the closure to be used allows very little oxygen ingress.

Question 16

What causes light strike?

What does this fault smell like in wine?

Answer 16

• Caused by UV radiation and certain wavelengths of visible light that react with certain compounds in the wine to form volatile sulfur compounds;
• Smells like dirty drains and other sulfuric compounds.

Question 17

What are three ways to avoid light strike?

Answer 17

1. Don’t leave wine in direct sunlight;
2. Don’t store wine near fluorescent lighting for extended periods;
3. Bottle wine in dark green and brown glass (wines in clear glass are most likely to be affected).

Question 18

Brettanomyces, which some wine drinkers say can add to a wine’s complexity, becomes a fault when its off-odors dominate a wine.

What does the wine taste like when Brettanomyces is considered a fault?

Answer 18

• The wine’s fruity flavors are diminished;
• The acidity and tannins become more prominent;
• Overbearing notes of animal and farmyard smells.

Question 19

Name four ways to avoid Brettanomyces becoming a fault.

Answer 19

1. Meticulous hygiene in the winery;
2. Maintaining effective SO₂ levels;
3. Keeping pH levels low;
4. Keeping the time between the end of alcoholic fermentation and malolactic conversion as short as possible so that SO₂ can be added.