Wine Faults

The subject of faults in wine has been extensively researched and discussed in wine writing.  There are hundreds of faults that could be present in wine and since we’re here just to provide some light reading, rather than a doctoral dissertation, we’re just going to touch briefly on a few of the most common problems you might come across in your wine.  The good news is that while some faults might be a bother, most of them are not going to physically harm you- they may just put a damper on your drinking session!


First things first, when you are buying wine in a restaurant, oftentimes there will be a sommelier on hand to help you in identifying any faults and this takes the pressure off checking for faults yourself.  The sommelier will present the selected wine to you to identify any defects and approve before the glass is poured.  Why not open a bottle of De Toren, Délicate NV, and practice the tasting process?

De Toren, Délicate NV

This ritual is not for you to check if you like the taste of your wine before committing to a whole bottle.  Unfortunately you can’t politely return it once it has been opened for something else if afterwards you decide you now feel like a lighter Pinot instead of the bold Cabernet you just ordered.   However, if you don’t have the guidance of a sommelier, knowing some basic wine faults can be a worthwhile skill.

Cork Taint


Let us touch on the dreaded ‘cork taint’.  Cork taint is a contaminant in wine – called TCA or 2,4,6-trichloroanisole.  Wine does not become corked because it is “off”, old or badly made- often we see ‘corked’ being used as the blanket statement of blame for anything somebody doesn’t like about a wine.  TCA tainted wine usually stems from a faulty cork.  A cork can be infected with the fungi that often originates in the tree from which the cork was made.  Once that infected cork is inserted into the bottle that wine will become defective.  The resoundingly obvious sign of TCA is a strong unpleasant aroma of damp or rotting cardboard.  It is usually very pronounced and once you know what you’re looking for it can easily be identified.  Cork taint also dulls the other aromas and flavours of a wine.  If you can’t smell the damp cardboard notes confidently then the muted expression on the palate of the wine will often be your next best indicator.


Unfortunately, there is not much one can do about a corked wine.  There are claims that one can salvage a corked wine by submerging a ball of cling wrap in the wine or decanting the wine into a cling wrap covered jug, but it may be best for your sanity to just wish it well on its way down the drain.



Wine that is oxidized and gone bad

Oxidation is probably the most common fault in wine.  Some wines are made in oxidative styles, for example certain types of sherry.  Naturally, all wine oxidises as it ages, however, the goal is for the rate of oxidation to be controlled and as slow as possible, adding to complexity and the development of character of the wine.  Premature oxidation describes rapid and uncharacteristic oxidation that can occur in a wine usually caused by a damaged or defective closure allowing for a larger than normal amount of oxygen into the bottle.  Oxidised wines turn brown, lose their fresh fruit characteristics, can smell musty or taste like browned apples.


As you can imagine, these wines are not pleasant for consumption, and you’d do well to just open another bottle, or begin making a stew or casserole.  If you are buying a ‘drink now’ fresh and fruity bottle of Sauvignon Blanc and then leaving it on your shelf for 20 years it will naturally be totally oxidised when you open it.  This, sadly, is only your fault.  You can test this with a lovely bottle of Dornier, Cocoa Hill Sauvignon Blanc 2021.

Dornier, Cocoa Hill Sauvignon Blanc 2021


Reduction and Volatile Sulphur Compounds


The presence of volatile sulphur compounds is a characteristic of ‘Reduction’.  As with most faults, while some aren’t so bad – reductive characteristics can become particularly problematic.


In short – Sulphur is stinky.  The presence of hydrogen sulphide can be caused in fermentation by unhappy yeasts.  Yeasts can become unhappy for a variety of complex scientific reasons, so we won’t go into them much, but ultimately stressed yeasts create hydrogen sulphide.  This results in aromas of rotten eggs and sewage.  Because of this risk, winemakers place much importance on achieving happy and healthy ferments.  If hydrogen sulphides aren’t removed quickly, they can produce mercaptans.  Mercaptans are responsible for many different unpleasant aromas such as rotten cabbage. Certain mercaptans showcasing flint or struck match can be appealing and contribute to making the nose of a wine interesting.


The list of these sulphur compounds continues quite extensively, for wine geeks looking to dive deep into the sulphur pool, we recommend you read Jamie Goode’s comprehensive article titled Mercaptans and Other Volatile Sulphur Compounds in Wine.


If you come across a reductive wine, often incorporating oxygen into it can greatly help reduce these smelly aromas – so give your wine a good decanting and keep swirling!


Brettanomyces (Brett)

Brett is a yeast spoilage commonly associated with red wines.  In large quantities Brett can present as the smell of Elastoplast or Band Aids – think of the smell of a hospital – it is not something you’d like to find when you put your nose in a glass!  In small amounts the presence of Brettanomyces can showcase notes of farmyard or sweaty animalistic characters.  While all of this sounds rather dreadful to some, our horse-loving friends will vouch wholeheartedly for a bit of Brett, and argue that it increases the complexity of the wine making for an all-round more enjoyable drinking experience.

Cooked Wine and Lightstrike

Just like us humans, wine is a sensitive natural product that needs to be protected from heat and UV radiation damage.  Cooked wine, otherwise known as maderised wine is a simple fault to identify.  It occurs when wine is stored in excessively hot conditions.  Fresh fruit characteristics in the wine turn to cooked, jammy flavours with notes of caramelised sugar.  While this sounds like a lovely description of a dessert – loss of freshness leads to loss of finesse and imbalance in the wine.


Lightstrike usually affects white wines with more delicate aroma and flavour profiles.  Wines bottled in clear glass are particularly susceptible to being harmed by UV radiation.  Both of the above defects are avoidable, so be kind to your wines by storing them away from direct sunlight and in a cool place.


Secondary Fermentation

Secondary Fermentation occurs when residual sugar in the wine begins to referment.  It is more likely to occur in natural wines that are not stabilised with sulphites.  Carbon dioxide, being a natural byproduct of fermentation, begins to be released and disseminated into the wine, creating unwanted fizz.  When you open your bottle of wine and it sounds like you have opened a can of soda, or the wine comes out resembling some sort of bubbly – there is a problem.


Faulty or Not Faulty?

And finally, not every imperfection in a wine is considered a fault.  Wine is an interesting natural product – it is not perfectly predictable all the time.  This is especially the case with tartrate crystals.  Tartrate crystals aren’t really a fault, sometimes unfiltered wines with high mineral content can develop these crystals which look like tiny pieces of glass that settle at the bottom of the bottle.  Many winemakers have had to put together a glamourous rebrand for tartrate crystals and fondly refer to them as ‘wine diamonds’ so that customers don’t return bottles of perfectly good wine in a panic.  These are totally harmless and do not affect the taste of wine at all.  If they are really bothering you, you can decant the wine with a filter – but really – that just takes more time to get to the sipping.


The most important thing to remember when it comes to wine faults is that if you genuinely can’t taste any issues and you’re enjoying your wine, even if there is a fault present, don’t kill your own party by overthinking it!


Our a glass of De Grendel, Merlot 2019, and practice your fault finding skills…  It should take multiple bottles to find one.

De Grendel, Merlot 2019

This blog was edited and posted by Digital Squeak.