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10 Common Wine Faults and How to Spot Them

A pile of different wine corks from various types of wine.
Cork taint is one of several different common wine faults to look out for. Photo by Elisha Terada on Unsplash.

Sometimes, and sadly, faults can occur in wine. Perhaps unsurprisingly, these are called wine faults. A wine fault happens when something has gone wrong either with the grape, the fermentation or production process, the aging, or the storing of the wine after it is bottled and sent off to its new home.

Wine faults are actually relatively common, if you are a wine drinker then you have probably had your fair share of wine with faults in it without even noticing. You may have even liked the wine more, or just written it off as a bad grape.

Fault or Flawed Wine?

In fact, what some may consider being a fault in the wine may actually be a deliberately crafted nuance in the drink. These can be defined as wine flaws- as they don’t so much disrupt the wine, but they can add to them quite nicely. An example of this would be Brut, which in small quantities can produce a farmland-style smell. Some people hate this, some people love it and seek it out.

This is a good example of how in small quantities, a flaw or a fault in your wine may add to it in a positive (for some) way, but others may hate the nuance.

So, what are some of the most common of these wine faults, how do they happen, and how do you know that they have happened?

1. Cork Taint

Also known as: Corked Wine, or Trichloroanisole (the scientific name- also known as TCA)

How To Identify it: Cork Taint can be recognized in two ways. If, when inspecting the nose of the wine, the aromas and the flavors are muted or dull then it could be that your wine has been corked. It will also taste flavorless and you won’t be able to identify any of the fruity characteristics that you would expect from a glass of wine.

Perhaps more seriously, if your wine is plagued by the smell of things like wet dog, wet newspaper, or that dark and dingy basement you avoid heading into, then there’s a pretty high chance that your wine is corked. Essentially, if your wine is full of musty, wet, and old aromas, then you will know that it is probably suffering from cork taint.

Fault or Flaw?: Unlike many wine flaws that can be considered beneficial to the wine, corked wine is considered a fault wherever it appears.

What Causes it?: Most winemakers make their corks from tree bark. If a batch of their tree bark is already infected with cork taint, then it will ruin any wine that they use it for. Unfortunately, there’s not really any way to tell if a tree is infected with what will become cork taint.

Cork taint is caused by Trichloroanisole- a chemical compound. This compound is found when certain bacterias and fungi come into contact with pesticides used in the 1950s for about 30 years, which can, unfortunately, still be found in the soil. These two things react together to form Trichloroanisole, which damages any wine that it touches.

There are other, less common ways for wine to be infected with cork taint (things such as barrel aging, and certain reactions with bleach and a wood compound called lignin), and in these ways, it’s even possible for screw cap wines to suffer from an infection of Trichloroanisole. While cork taint can happen to screw-topped wine, it is very uncommon.

Can I fix it?: Unfortunately, you cannot fix a wine that is corked. It’s best to just return it to where you bought it from.

2. Oxidized Wine

Also known as: Oxidization

How to Identify it: If your wine is darker than you would expect it to be (or if it is darker than it was when you initially bought it). The wine will lose some of its vitality- both in color and in flavor. An oxidized white wine will slowly turn from golden yellow to a sad brown, and an oxidized red will lose all of its punchy purple and red colors, sinking into oranges and browny-reds.

The more oxidized your wine is, the more prevalent these colors will be. This is the same process as what happens when you cut an apple or a potato and leave it to the air, as it darkens. More than just colors, an oxidized wine will begin to taste more and more like vinegar. This is because the naturally occurring acetaldehyde in the wine turns into acid, creating the vinegar, or even copper penny smell.

Fault or Flaw?: Oxidization of wines is a common part of the wine-making process. Many, many wines are oxidized as they are made. Even, when you take the wine home, decanting a bottle of wine or even swilling it in your glass, is a method of oxidization. The issues arise only when the wine is over oxidized.

If a wine is over-oxidized then it is undoubtedly a flaw.

What Causes it?: Simply, overexposure to oxygen. Exposure to oxygen is a vital part of the wine-making process for many types of wine. Oxidization, when done in moderation, can transform a wine. Think the softening of wine heavy in tannins. A wine you enjoy with earthy, nutty flavors is thanks to oxidization. Oxidization is also what we can thank for the more subtle secondary and tertiary flavors while wine tasting.

Can I Fix it?: There are rumors flying around that you can reduce oxidization in wine by stirring in powdered skimmed milk and leaving it to rest for several days. This won’t leave you with a bottle of world-class wine, and it probably won’t even taste like the wine that you originally bought. We don’t recommend this.

However, if you have bought the wine oxidized, we recommend taking it back. If you have left it open too long and it has oxidized in your home, we recommend investing in some wine preservation tools.

3. Reduction

Also Known As: Sulphur Compounds, reductive wine.

How to Identify it: Reduction in wine is basically the complete opposite of oxidized wine. It is a wine that is made without sufficient oxidization. This can be deliberate, and such wines will be extremely fruity and acidic. However, a badly reduced wine will have an overly sulfurous smell, often reeking of eggs, matches, or other delightful swap notes.

Fault or Flaw?: Fault, but one that can be fixed.

What Causes it?: The lack of oxygen in the winemaking process means that the wine can’t polymerize, as there simply isn’t enough oxygen for the molecular process to happen.

Can I Fix It?: Sometimes. If you leave the wine to decant for longer than you might usually, this can help. You can also try stirring it with pure silver, which is known to reduce the amount of sulfur in the drink.

4. ‘Cooked’ Wine

Also Known As: Heat Damage, Madeirized wine.

How To Identify it: If you’ve ever reduced wine while cooking, then you already know the sweet, jammy flavor that it invokes. You’ll be able to identify a cooked wine as it will be extremely sweet (when it shouldn’t be) with perhaps a roasted nut flavor to it.

You will also be able to recognize it through a change in the sealing of the bottle. Often if a wine is cooked then the cork will be pushing out of the bottle and the seal will be affected too. This can happen before you purchase the wine or if you have not properly stored the wine in your home.

Fault or Flaw?: Depends on where the wine is from. If it is from Maderia in Spain then it’s a deliberate feature, and so a flaw. However, if it is not then it is undoubtedly a fault.

What Causes it?: Heat. Wines should generally be kept quite cool, so if a wine spends a long time in high heat, for example, a bottle of wine left in your window in the summertime, it is likely to experience heat damage or cook- ergo cooked wine.

Can I fix It?: No. The best thing you can do is carefully inspect the bottle before you buy it to ensure that the cork is in place and then store it appropriately. Try to keep your wine at around 13°c or 55°F.

5. Tartrates

Also Known As: Tartrate Crystals, Glass Shards.

How To Identify It: Tartrates are small crystal-like mineral deposits that can be found at the bottom of some bottles of wine- most commonly old bottles of wine. They are not harmful (and are certainly not glass).

Fault or Flaw?: Neither. In fact, they are a sign of high-quality, aged wine.

What Causes It?: You will find wine crystals in your glass if the wine-maker didn’t filter the wine before it was bottled. Many choose not to filter the wine because an unfiltered wine will retain its textures and flavors better.

Wine crystals can also be caused in the aging process, as parts of the wine react together and solidify, sinking to the bottom.

Can I Fix It?: There’s not much to fix, just strain the wine into your decanter before serving it.

6. Volatile Acidity

Also Known As: Acetic acid

How To Identify It: A very acidic wine, often smelling a little like balsamic vinegar. Your wine could also smell like a nail polish remover.

Fault or Flaw?: Depends on the wine. Some wine benefits from a spike of high acidity. Sometimes, the level of acidity can ruin the wine and remove all of the fruit flavors.

What Causes It?: The bacteria acetobacter. This is the bacteria that is used to create acidity in wine, the issue comes when the bacteria get out of control as it can completely destroy a wine.

Can I Fix It?: You’re not likely to find volatile acidity in store-bought wine. It’s likely to become a problem in home-brewed wines that try to capture acidity. Once the wine has soured, it can’t be fixed.

7. Ladybird Taint

Also Known As: Pyrazine, ladybug taint

How To Identify It: The wine smells off. Expect smells like very moldy peanut butter, urine, extreme bitterness, or even just green bell peppers.

Fault or Flaw?: Absolutely a fault.

What Causes It?: During the harvesting process, it’s somewhat inevitable that some bugs will end up in the mix. For the most part, there is no problem with this. However, some bugs (most notably, specific types of ladybugs) can have a defense mechanism that means they emit nitrogen heterocycles, an unpleasant smelling substance that, in sufficient quantities, can harm the taste and smell of a wine.

Can I Fix It?: No, this problem comes from the harvest of the plant. It’s best to just return the bottle.

8. Brett

Also Known As: Brettanomyces

How To Identify It: If your wine is giving you serious farmyard vibes, then it’s likely to be brett. Horses, hay, and even band-aids are what you will be smelling when you are drinking a brett heavy wine.

Fault or Flaw?: Technically a flaw, serious wine drinkers are divided on the subject of brett. Some love it and seek out the complexity that it gives a wine, others condemn a bottle that has so much of a whiff of hay bales.

What Causes It?: Brettanomyces is a type of yeast, and produces molecules towards the end of the fermentation process. In some wine, these molecules can with the existing phenolic compounds (the part of wine that makes the smells of other fruits)

Can I Fix It?: Nope, and it’s not something that is intended to be fixed. While too much brett can overwhelm a wine, it’s mostly there to add complexity and flavor.

9. Mousiness

Also Known As: Just Mousiness.

How To Identify It: Similar to brett in a ‘natural smells’ category, mousiness can give off the rather unpleasant smell of a mouse’s cage, or mouse urine, vomit, or even things such as rice crackers. Mousiness is not something that you can identify when it is in your glass. Unfortunately, the smell becomes apparent only once you have the wine in your mouth and you have allowed it to oxidize there.

Fault or Flaw?: Fault, found only in natural wines.

What Causes It?: Natural wines don’t use the preservative sulfur dioxide. Mousiness appears almost randomly in wines that don’t have the preservative in them. People also have naturally different sensitivities for this so you may find the taste overwhelming, while your tasting partner may not notice.

Can I Fix It?: No, but since the aromas are only released after a few seconds in your mouth, you could of course, just drink it faster. This will interrupt the tasting experience, but it will allow you to taste without mouse-related worries or flavors.

10. Refermentation

Also Known As: Secondary fermentation, bubbles in the wine.

How To Identify It: You will see small bubbles in a wine that shouldn’t otherwise be bubbly. It is especially prevalent in young bottles of red wine. You may also hear as you open the wine a sound similar to opening a bottle of soda.

Fault or Flaw?: Sometimes a fault, sometimes an active choice by the wine-maker. Research the brand a little to see if the bubbles are deliberate or not.

What Causes It?: When a small amount of residual sugar is bottled along with the actual wine. This excess sugar will cause a second fermentation. This is more common in natural wines, as they don’t have sulfites added, which tend to stabilize a wine.

Can I Fix It?: Not exactly, but you can let the bubbles disappear on their own. Just pour it into your decanter and stir vigorously.

Final Notes

If your wine tastes funny, then it might be to do with a wine fault that you have not noticed before. In fact, there may be some wine faults or flaws that you actually find that you very much enjoy, such as brett.

Hopefully, this article has given you a good handle on what works well for you, the type of flaws that you like, and some helpful tips to fix a wine fault that you find is not to your personal taste.

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