Defect & Organoleptic Flashcards
1
Q
My family of related compounds is responsible for the highly aromatic, floral and sweet citrus notes of Muscat Blanc à Petits Grains, Gewürztraminer, Torrontes, Viognier, and (to a lesser extent) Riesling and Albariño?
A
- Monoterpenes
2
Q
Diacetyl is responsible for what flavors?
A
- Slightly buttery, nutty notes in wine, and it is especially noticeable in white wines. It is one of the two compounds primarily responsible for the flavor of actual butter, and the chemical is used to flavor margarines and other artificial products. At high levels of impact, diacetyl is generally considered a fault. At the conclusion of malolactic fermentation, diacetyl accumulates in wine. While diacetyl is also a byproduct of primary fermentation, only during “malo” do its levels begin to surpass thresholds of perception.
3
Q
Smell of coconut is often associated with..?
A
- American oak barrel aging. The whisky lactone appears in wines aged in new oak. It was first identified as an aromatic compound in whiskey in 1970, and it has a sweet, woody, coconut-like fragrance. American oak barrels contain larger concentrations of whisky lactones than French barrels
4
Q
Wines with slight residual gas? What causes it?
A
- Albariño and Gruner Veltliner - excess of dissolved carbon dioxide that becomes sealed in the bottle (sur lie aging) – especially common in screwcap—closed bottles. Nouveau and other young carbonic red wines often display a light spritz.
5
Q
What is Volatile Acidity ?
A
- The formation of acetic acid and related compounds by the action of bacteria during the winemaking process. Acetic acid smells slightly vinegary. Fairly common in barrel-aged reds and whites, and particularly in sweet wines.
6
Q
Which wines commonly have VA? What causes it?
A
- Italian Nebbiolo, Sangiovese and Corvina based-blend. It often appears in old vessels barrel-ageing.
7
Q
What is Ethyl Acetate wine fault?
A
- A variation on volatile acidity, caused by a bacteria. Has a smell like nail-polish remover.
8
Q
What is reduction ?
A
- Generally speaking, reduction is the contrary of Oxidization ; there is not enough oxygen. It is common with after fermentation lees ageing. It enhances the blackcurrant notes of Cabernet Sauvignon, or the passionfruit tones of Sauvignon Blanc. Sulfur off-odors are a particular problem for screwcap-closed wines.
- Reduction is the common name for the above-threshold presence of volatile sulfur compounds (VSCs) in wine. The most basic VSC is hydrogen sulfide, which smells of bad drains and rotten eggs. Other VSC aromas include cooked cabbage, onion, gunflint, and sweet corn.
- It’s caused largely by yeast metabolism. Yeasts produces VSCs in certain condition, such as low nitrogen availability. Sometimes reduction develops after bottling, especially where low-oxygen-transmission closures are used.
9
Q
What is TCA ?
A
- 2,4,6 Trichloroanisole – formed in cork bark by the chemical combination of phenolic compounds with chlorine. The phenolic compounds in TCA are present as a result of the breakdown of lignin, which is the hard substance naturally occuring in tree bark. The chlorine comes from the environment. It is widely accepted that the major source of environmental chlorine in cork oak forest are organochlorine insecticides that were widely used from the 1950s to the 1980s. Even though they are no longer used, chlorine residues are still present in the soil at the base of the trees and will remain there for some time.
10
Q
What is Smoke Taint ?
A
- When grapes are exposde to smoke during the ripening process, they can end up making wines taste ashy, bitter, and unpleasant. It is cuased by wildfires near vineyards, towards the end of the growing season.
11
Q
What is Geosmin ?
A
- earthy-smelling sesquiterpene produced by Penicillium expansum. It’s a microbial fault that seems to be common in damper vintages. It’s also encountered as a cork taint. It causes both red and white wines to smell of freshly turned earth, beetroot, and mustiness. It is caused by the growth of Penicilium expansum on grape bunches that have already been attacked by Botrytis Cinerea, and by mold growth on cork during processing. It can be confused with cork taint.
12
Q
What is Eucalyptus Taint ?
A
- When grapes are grown in proximity to eucalyptus trees, the resulting wines can develop a eucalyptus character. Affected wine are described as minty, medicinal, and eucalypt-like. Its caused by an aromatic commpound called cineole, from the leaves of the trees, finds its way onto grape skins, and from there into the wine. Its also transmitted by tainted leaf and bark material that finds its way into the wine, which may be the most significant cause of the problem. Its far more common in red wines because of the skin maceration.
13
Q
What is Light Damage ?
A
- Loss of quality caused by exposing wine to light. It causes oxidation of the wine by depleting free SO2 levels and/or causes the development of off-odors from volatile sulfur compounds. More common in rosés, which are almost always bottled in clear flass, and more common in sparkling wines.
- There is 2 mechanisms that can cause the fault ; eiher the formation of glyoxylic acid from tartaric acid in the presence of iron or photogeneration of volatile sulfur compounds from methionine and cysteine.
- Descriptors usually used to describe this lightstrike are ‘skunky’, ‘cooked cabbage’, and ‘onion/garlic’.
14
Q
What is Heat Damage ?
A
- High temperatures affecting wine chemistry in negative ways. Wines ages prematurely and are prone to oxidation.
15
Q
What is Mousiness ?
A
- A distinct flavor/aroma of mouse cages that can’t be smelled until the wine is in the mouth. Its slightly sweet and earthy – not musty, but not completely clean. Its a strange taint, in that it isn’t detectable on the nose but appears on the palate after the wine has been in the mouth for a few seconds or even sometimes a bit longer. It is experienced retronasally if the pH of your saliva is able to increase the pH of the wine sufficiently. It’s thought to be caused mainly by lactic acid bacteria, but it’s possible that it may be formed chemically too. Its common in natural wines, especially reds, where the pH is a bit higher. Up to a third of the population aren’t able to spot it at all.
21
Q
What specific aroma Furfurylthiol is responsible for ?
A
- Coffee
