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The Different Faults Found in Wine

After a long day in the office, itching to get home and enjoy a relaxing glass of wine is the highlight of most days. The last thing anyone one of us would like to experience is a faulty wine. Not only will it dampen your mood, but that bottle you've been waiting to crack is now ruined.

The most common fault that most of us are familiar with is cork taint, which is something we unfortunately cannot predict. However, there are a few others such as reduction, oxidation, heat damage and volatile acidity which aren't too familiar to some us.

We are going to break down each one of the major faults found in wine, so that you will have an easy reference and garnish a better understanding of them so that next time, you will be able to pick out all major faults.


Cork Taint:

When a wine smells of wet cardboard, a wet dog, a musty cellar or of a damp forest floor, then it is most likely what we refer to as a corked wine. The cork taint is caused by a powerful chemical compound called 2,4,6-trichloroanisole or TCA for short. TCA is formed by the interaction of plant phenols, chlorine and mold. It is most commonly found in wines that have natural corks (as cork is from a tree), but can also be found in wineries, where 90% of the time, a cellar will have damp surfaces and chlorine-based cleaning products present. Oak barrels are easily affected if TCA is present in the cellar as oak is a plant phenol.

TCA poses no threat to your health, however it ruins your wine and unfortunately makes it undrinkable, which is enough to ruin anyone’s day especially if it is a very prized wine. To be fair, only 5% of wines with natural corks have been affected by TCA and it also depends on your personal perception. People vary widely in their ability to perceive TCA in wine, depending on their genetics and experience. Some cork producers claim that levels of 6 or even 10 parts per trillion (ppt) are acceptable, as many people won't notice TCA at this level. Some tasters can detect TCA at 1 ppt to 2 ppt, and a rare few can perceive it at even lower levels.

So regardless of your threshold of perception, having a cork taint in your wine is few and far between. If you don’t want to run the risk, then screw capped wines are your safest bet.

Learn Why Screw Caps Are Better Than Corks

The development of TCA - Photo Credit: winesignofindia.comTCA


Reduction is a winemaking technique that goes hand-in-hand with oxidation. While the two are complete opposites, they can both have negative outcomes if not controlled properly during the winemaking process.

To understand this, oxidative wines are wines that are exposed to oxygen naturally and is commonly practiced in traditional winemaking through open-top fermenters and/or even during racking. Reduction on the other hand is a complete 360 where wine is made with very little presence of oxygen by using stainless steel tanks and by inserting gases such as nitrogen into the tank. The purpose of reductive winemaking is to reduce the exposure a wine has to oxygen to maximize the fresh fruit flavours in a wine. Please note that wine does needs a certain amount of oxygen to have its molecules combine to give you the fresh fruit flavours, and if it doesn’t, then it becomes a fault.

So how is reduction a fault? It becomes a fault when there is too little oxygen present that results in the buildup of hydrogen sulfates and as a result, wines will smell like rotten eggs, garlic, boiled cabbage, rubber, struck matches, sewage and even skunk. These are not pleasant characters in a wine.

In a nutshell, reduction is basically caused by a wine receiving too little oxygen.


Unlike reduction receiving too little oxygen, an oxidized wine basically is exposed to too much oxygen, more than what it is necessarily exposed to through traditional winemaking practices. Like any fruit exposed to oxygen, it will slowly start browning in colour, much the same will happen to the wine. The colour fades, the fruit flavours become dull, it will start to smell and taste very nutty with very common flavours of bruised apple (cider like) and become very reminiscent of Sherry.

Oxidation can happen in 3 parts:

  • During the winemaking process
  • If a bottle is left open for too long
  • A really old wine that has seen its day. We refer to this as being a "tired" wine.

An example of what oxygen can do to an apple - Photo Credit: vinepair.comoxidation-internal

Heat Damage:

Heat Damage occurs when a wine has been exposed to temperatures above 20°C for an extended period of time. This will cause your wine to turn brown in colour and taste flat and sour. Also, if there is too much fluctuation in temperature, wines with a cork will be more susceptible to damage, as the temperature fluctuations cause the cork to expand and contract, which will allow more oxygen to penetrate (this will increase the risk of oxidation) as well as after time, the cork will eventually lose its elasticity, become brittle and break and then a you will have a leakage of wine

If keeping wine for an extended period of time, it is important that the storage temperature is regulated and consistent. Without a wine fridge, storing wine at what is considered an ideal temperature between 10-13°C is pretty impossible. However, wine can still lay and relax at around 20°C maximum. If you do not own a wine fridge, a dark room will come in handy without any direct sunlight.

Volatile Acidity:

Volatile Acidity (VA) is a measure of a wines volatile acids. The primary volatile acids in wine are acetic acid - which we commonly associate with the smell and taste of vinegar and ethyl acetate – which smells like nail polish remover. VA is linked to an over exposure of oxygen and/or lack of sulfur dioxide management. Acetic acid bacteria requires oxygen to grow and escalate. So if your wine smells like vinegar and nail polish remover then it has been affected with VA.

VA can occur during the following winemaking practices:

  • Cold soaking
  • Natural fermentations
  • Stuck or sluggish fermentations
  • Barrel ageing
  • Prolonged oxygen exposure in tank or barrel
  • Post-bottling, especially when wines are not properly treated with sulfur dioxide or sterile filtering.

So in order to minimize the chances, wineries need proper protocols in place to make sure that VA is not present. Wineries need to make sure they do proper sulfur dioxide treatments (enough to kill the bacteria), adequate temperature control during fermentation, thorough sanitation practices, and appropriate oxygen management strategies. If these practices are followed and done correctly then wineries shouldn't have a problem with VA at all.

A typical reaction when one smells VA in a wine - Photo Credit: Buon VinoVA reaction

So I've tried my best to make everything as clear and concise as possible. I hope that from this you now feel more comfortable and confident in your decision making when it comes to picking out a faulty wine. 

As mentioned, everyones personal thresholds of perception is different so some of us may or may not be able to pick out the discrete faults and how intensely they have impacted the wine, but I encourage you, no matter how small the fault may be, to think twice and question yourself if you do think that the wine may be faulty or not.

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