Faults

Question 1

Cloudiness and hazes

Answer 1

1) growth of bacteria due to not filtering adequately / remedy via better hygiene in the winery, pre-bottling chemical analysis, and the filtering of yeast and bacteria
2) poor filtering of the wine at too high a pressure through a depth-filter that pushed particles through
3) protein haze due to ineffective fining, the wrong type of fining agent, or over-fining

Question 2

Tartrates

Answer 2

Colorless or white crystals often seen as fault by consumers, caused by failure to stabalize

Question 3

Re-fermentation in bottle

Answer 3

• cloudiness plus a spritz would indicate this
• caused by failure to stabilize and clarify/filter the wine

Question 4

Cork taint

Answer 4

• unattractive, moldy, wet cardboard smell that reduces fruit
• reduce or eliminate cork taint

Question 5

Oxidation

Answer 5

• the result of excessive exposure to oxygen in the winemaking process or once in bottle due to faulty bottling, poor quality corks, plastic containers, or simply keeping a wine for too long
• premature browning of color, loss of primary fruit, and a vinegary smell

Question 6

Volatile acidity

Answer 6

• all wines have it but in excess causes nail varnish/ vinegar aromas
• caused by acetic acid bacteria, inadequate SO2, and excess exposure to oxygen
• reduce threat by sorting to exclude damaged fruit, hygiene in the winery, keeping vessels topped up, careful racking, and maintaining adequate SO2

Question 7

Reduction

Answer 7

• sulfur-like odors from struck match to onion to rotten egg caused by high levels or reductive sulfur compounds
• in small levels can add complexity
• produced by yeast under stress due to low nitrogen levels during winemaking or due to complete exclusion of oxygen in closed vessels, especially during lees ageing
• can evolve under screw cap
• avoid by making sure yeast is not stressed by ensuring sufficient nutrients and oxygen and has adequate temperature, SO2 may need to be lowered

Question 8

Light strike

Answer 8

• caused by UV radiation and certain waves of visible light reacting with compounds in the wine to form volatile sulfur compounds, giving dirty drain odor
• wines left in direct sunlight are most at risk, then those near fluorescent lights especially if in clear bottles

Question 9

Brettanomyces

Answer 9

• brettanomyces yeast produces a range of off-aromas including animal, spicy, or farmyard smells
• some think it adds complexity at low levels
• at high levels fruit will be reduced and acid/tannin becomes more prominent
• once a winery becomes infected it is nearly impossible to eradicate especially with wood
• avoid via excellent hygiene, maintaining effective SO2 levels, keeping pH low, and keeping the Time between alcoholic fermentation and MLF as short as possible
• wine can be treated with filtration or dimethy; dicarbonate before bottling, deactivating it