How to find a wine fault?


JANUARY 9 | 2019

AUTHOR | Kris Graczy

Cork taint, TCA (2,4,6- Trichloroanisole)

Is the most common wine fault attributed to natural corks, but its not the only one. Its a compund with very strong odour that can overpower other properties in wine, masking wine quality. You can describe it as wet cardboard or moldy smell. TCA its typically converted by molds from its precusor TCP, which was commercially used as herbicide, insecticide, wood preservative and antiseptic. Its an air pollutant. Has been banned for decades.

TCA can end up in wine prior bottling. Older wineries in particular may be made of framed with wood that was treated with TCP as a preservative. Finally, cork can also get contaminated by storage in or on any container already contaminated with TCA, such as wooden pallets.

Wine will loose its beautiful fruity characteristic affected by a bad smell. I reccomend You sending it to a place You both it. Especially if You purchesed it in the Winery, they would most likely change it for a new bottle.

Vinegar odour (Ethyl acetate)


If you open a bottle of wine and it smells like a vinegar its not always a sign that wine is spoiled. Some winemakers during production purpously leave high concentration of acetic acid to create a more complex taste. Vinegar smell is form in wine by the esterification of ethanol and acetic acid. High levels of ethyl acetate are produced by acetobacter, wine spoilage yeast or acetic acid bacteria.

Simply if You dont like that Your wine smells like a vinegar refuse to drink it, send it back. There is no option to fix that fault. But some people think that good red should smell a bit like that.



It’s a chemical reaction when alkohol is contaminated by to much oxygen. There are an exchange of electrons. First one is exposed by oxidation of phenols. Same reaction heppens when You leave banana on a counter for fews days and its turning brown color. Second one is by oxidation of ethanol which is giving bad aromas like peanut or sherry.

To protect wine from oxidation, winemakers adding sulfur dioxide or erythorbic acid which are biding with some of the oxidation products to reduce their organoleptic effects. Thats why when You store wine at home, dont forget to place a bottle in a horizontal position. So the wine touch the cork to keep it moisture around 8%. Otherwise cork will be dry and to much oxygen will be incorporated inside the bottle.

Older red wines turning light orange, brown color because of oxygen exposure during aging. Opposite to white wines when they getting more color with age. From light yellow color turning to golden. Oxidation is the most common wine fault and You cant help it when its already happened

Sulfur compounds


Sulfur dioxide is added to almost all wines to preserve them and prevent oxidation. Sometimes when You open a bottle it will have strong smell of matches. It means that to much sulfur was added to wine before bottling.

Another compund can apear during fermentation when yeast has limited nitrogen environment. Then hydrogen sulfide would be metabolized. We will have very unpleasent wine aroma simmilar to rotten eggs odour. Mercaptans are produced in wine by the reaction of hydrogen sulfide with other wine components such as ethanol. Those causing onion, rubber and skunk type odour.

You can refuse to accept a bottle of wine with a strong sulfur odour or You can try to decant it. Cause sulfur dioxide is easily reacting with oxygen and can disapear with about an hour

Heat Damage


Properly stored wine should be in a dark place with about 70% humidity and temperature around 13 degrees Celcius (55 degrees Farenheit). If the wine would be constantly keep over that temperature it will be cooked or maderized. Wine under extreme temperatures will thermally expand and it may push up the cork and leak from the top. If You remove a foil and see a layer of wine on a top of a cork, most likely its a cooked wine. Heat damaged wines often push out a cork then become oxidized, and red wines may take on a brick color.

Make sure You store a wines in a constant temperature, away from light and dry places. All corks allow some air incorporate inside a bottle, but temperature fluctuation will pump up air in a faster rate then maintained temperature.

UV light (Lightstroke)


Did You ever wonder why producers using dark color bottles for their wines? Answer is… To protect them from ultraviolet light. It can affect a wine causing wet cardboard or wet sweater type aroma. More sensitive to light are whites. Red wines has phenolic compounds present within the wine that protect it. In France lightstrike is known as “goût de lumière”, which means a taste of light.

Remember to keep a wines in a dark place to prevent a lighstroke. Especially Champagnes and light white wines (Pinot Grigio, Sauvignon Blanc) are very sensitive to uv light. Less sun exposure gives better agibility to Your wines.

Brettanomyces (Brett)


It’s a type of wild yeast that can appear in any stage of winemaking. Yeast are microorganizm that lives on a grape skin or simpy in a cellar. They are on a walls, tanks, clothes and barrels. Some of them has unpleasent aroma like Brett. When shows in Your wine bottle, would smell like a band-aid, barnyard or cow-pie. Some winemakers consider a bit of brett as their house style, but for others, once brett takes residence in a cellar, it can be difficult to get rid of.

Some people don’t notice it and others are sensitive to it. Its not causing any health issues unless You consider drinking band-aid wine a menthal health problem.



This compound is produced in wine by lactic acid bacteria during malolactic fermentation. In low concentration can have possitive impact on wine, showing nutty or caramel character. But in extensive form, giving buttery, butterscotch flavour. It can be produced as a metabolite of citric acid when all of the malic acid has been consumed.

Rarely wines with high diacetyl level become undrinkable. Its a personal preferance if You like Your wine to be oaky, buttery with strong vanilla flavour or not.

„The wine which demands a second, then third glass, can never be a bad wine.
The wine of which You cannot finish one glass, can never be a great wine.” 

– Ernest Gallo

Kris Graczy

Kris Graczy

Wine Consultant

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