Wine has that beauty that can make anyone fall under its spell- the aromas and boundless flavors that evolve with age, the numerous complexities and textures; wine is certainly a mixture of different chemicals and compounds that contribute in the making of such a delicate and fragile liquid. And yet who would think that this exquisite and "flawless" wine has the tendency to go bad? It can be a real pain to see your favorite wine being flawed. Since it is made with natural ingredients, just like any other product it can go bad. However, detecting wine faults can be tricky at times; here we take a look at some of the common wine faults and how they can be detected.

1. Corked Wine

What is it?

A corked wine doesn’t mean tiny particles of cork floating in the glass. This term is used for a wine that has been contaminated with cork taint. The presence of the chemical compound 2,4,6-Trichloroanisole or Trichloroanisole (TCA) is responsible for cork taint. TCA is formed when a natural fungus creates a chemical reaction with certain chlorides found in winery sanitation and sterilization products or when the fungus interacts with the natural cork. This defect can be caused via corks that haven’t been cleaned properly in the cork making process, oak barrels, or the processing lines at the winery. If large volumes of bottles are corked, TCA can ruin an entire batch of wine. Once the cork is contaminated there is nothing much left to do.

How to spot it?

TCA taint can be characterized by musty aromas like that of wet dogs or wet cardboard. The wine will seem dull, lifeless and flat.  As for the taste, corked wines have suppressed fruit flavors.

Estimations show that between 2 to 6 percent of all wines bottled under a cork are affected by faulty corks.

2. Heat Damage & UV Light Damage

What is it?

This defect is caused by a wine that has been exposed to high temperatures or UV light. Wines that are affected by heat damage are also called Cooked wines. Damage caused by light also known as Lightstrike occurs when a wine has been exposed to excessive ultraviolet radiation. White wines are particularly susceptible because they don’t have the same protective compounds as present in reds. The main reason for a wine to undergo this damage is because of the storage of wine near a window or in warm areas. 

How to spot it?

If your wine tastes flat and reminds you of an over-brewed cup of tea, chances are that your wine has been cooked. Your wine will come out of the bottle tasting like a sauce with stewed fruit qualities which is overly processed, concentrated, and sweeter than it should be. Generally off and burnt.

Cooked wines typically show signs of oxidation. The heat inside the bottle causes expansion, which will force the cork up and eventually out of the neck. In extreme cases, the bottle can leak.

3. Oxidation

What is it?

A wine that has been ruined because of too much exposure to oxygen is an oxidized wine. Oxidation is one of the most common wine faults occurring in older wines. This process happens naturally in wines as they age. When it happens slowly it enhances the complexities that can be found in mature wines. However, in young wines, this can be looked like a defect caused by faulty or weak corks which allow the oxygen to get inside the bottle and interact with the compounds. A little bit of oxygen is not a bad thing in the barrel aging process as it provides breathing space to the wine and opens up the flavors and aromas. When a sliced apple is left open on the counter it turns brown, same goes for wine, when kept in the presence of too much oxygen it causes the chemical balance to disintegrate thus flattening the wine.

How to spot it?

Oxidized wines are dull both in color and flavor. Reds take on brick hues and have an unpleasant aftertaste with vinegar characteristic. White wine turns to darker amber color with a brownish tinge. 

4. Secondary Fermentation

What is it?

When the wine is bottled before it is stable with some residual sugars left in the bottle, it starts fermenting, tiny bubbles or a slight fizz is seen to your table wine indicating there was a secondary fermentation. This can be off-putting for a non-sparkling wine and negatively affects the flavors.  

How to spot it?

The presence of bubbles in your non-sparkling wine is the best way to spot secondary fermentation. It can be found in young red wines. The wine tastes yeasty.

5. Volatile Acidity

What is it?

Volatile Acidity also known as VA is the high level of Acetic Acid. It is caused by the combination of too much air, heat, and bacteria during the winemaking process. The bacteria can be wild yeast present on the berries which creates acetic acid during fermentation which gives the wine a sour vinegar taste.

Many winemakers use this type of acid to add complexity to the wine and hence, it’s not considered a fault unless it is overpowering the rest of the chemical compounds. If the volatile acidity levels are excessively high they can destroy wine's fruitiness and kill its flavors and aromas. 

How to spot it?

The best way to detect it is a whiff of nail polish remover. The wine will be unpleasant to drink. VA smells and tastes like balsamic vinegar if it’s found at high levels.

6. Brettanomyces or Brett

What is it?

Brettanomyces is yeast also known as Brett which exists on the surface of the grape skins and also in the winery. It is most commonly a result of unsanitary winemaking practices such as un-cleaned equipment and barrels; it is incredibly difficult to get rid of. There are stories of wineries burning thousands of dollars of oak just to get rid of it. Today’s winemaking environment is much cleaner so there’s less chance of brett spreading. It is more evident in red wines that have low levels of sulfur dioxide.

How to spot it?

Generally, it smells like a barnyard dunk, stables or sweaty saddles and sometimes like a band-aid. Brett causes the wine to taste earthy and musty.

7. Reduced wine

What is it?

The opposite effect of oxidation, with oxygen wine oxidizes, without oxygen it reduces, meaning the wines are intentionally kept from being exposed to air to keep the fruit's aromas intact throughout the process. Simply put, reduction occurs when a wine is made without introducing enough oxygen in the winemaking process- be it in the cellar or in the bottle.  Just like all other living things, wine needs to breathe, if it doesn't sulfur compounds begin to form and we are left with a reduced wine.

How to spot it?

Smells like rotten eggs or old cabbage.