Wine faults…. and other things you won’t find in a bottle of Somerled wine!

Wine / Wednesday, November 15th, 2023

Although… no matter how good a wine maker you are and how good the wine is, it doesn’t always guarantee immunity to bad things happening.

Because bad things do happen.

And here are just a few of the bad things that can happen to wine (and how to identify them)…



Oxidation is caused by too much oxygen exposure. It is exactly the same process as when your sliced apple turns brown. Oxidation is the most common wine fault in older wines and is why you shouldn’t keep an open bottle of wine for more than a few days.

Tell-tale signs: Oxidised wines lose their brightness, both in colour and in flavour. Reds turn to a brownish-orange colour, and fresh tastes develop drier, more bitter characteristics. White wines are much more susceptible to oxidation than reds – the higher tannin levels in red wines act as a buffer.

Cork taint

Cork taint or 2,4,6-Trichloroanisole (TCA) is a chemical contaminant. It can be introduced into a wine at any stage during production, but most commonly comes from real cork. TCA can also be present in oak barrels, or the processing lines at the winery.

Tell-tale signs: Dank odour and a taste like wet newspaper, mould or smelly dog. YUMMY! The wine will be fruitless and dominated by these unpleasant flavours. It is the second most common wine fault.

Sulphur Compounds

Sulphur is a complicated issue in wine. As we know sulphur dioxide is added to almost all wine to stabilise it. Another sulphur, dihydrogen sulphide (H2S) results from unhealthy fermentation. It’s also not bad for you but can lead to some nasty aromas.

Tell-tale signs: Rotten egg or burnt rubber – you don’t want to smell anything like this when you sniff your wine.

Secondary Fermentation

Secondary fermentation is a good thing if we’re talking about sparkling wine, but if you find them in a young bottle of red that’s a fault. It usually happens when the wine is accidentally bottled with a few grams of residual sugar which then re-ferments. This most frequently occurs in low-intervention winemaking, where very little (or no) sulphur dioxide is used.

Tell-tale signs: Bubbles in your wine or it sounds like you just opened a bottle of soft drink when you unscrew the cap. There can also be a zippiness on your tongue. Not all secondary fermentation is an accident though. Some winemakers will use it to add a little kick to their wines. It also shouldn’t be confused with malolactic fermentation.

Heat Damage

“Cooking” a bottle of wine happens when it is exposed to too much heat… think about that wine you accidentally left in your car on a 40-degree day!

Tell-tale signs: The wine smells jammy: sweet, but not in a good way. The smell is somewhat like a wine reduction sauce, mixed with a nutty, brown, roasted sugar-type aroma. Heat damage can often break the seal of the bottle so it can also be accompanied by oxidisation. Make sure you store your wine in a cool place but more importantly ensure it is stored at a consistent temperature.

UV Light Damage

This is the damage that is caused by exposure to excessive UV radiation. It is also known as lightstrike and most commonly occurs when a wine is stored in the sun or near a window.

Tell-tale signs: It can make the wine taste like wet wool. It is most common in delicate white wines (Sparkling, Sauvignon Blanc, etc)

Microbial and Bacterial growth

Many microbes can live in wine, but if one of these colonies becomes too aggressive, it can cause various “off” aromas. In small amounts, these can add appealing complexity. If the colony becomes too vigorous though, these flavours become faults.

Tell-tale signs: Again, there are many other bacteria involved in winemaking. They all impart certain flavours and produce signature wine faults. Think of them like spices, in the right quantities they can add an appealing complexity; too much though and the wine becomes uninteresting. They can have medicinal (think menthol or cough drops), animal (barnyard, mushroom), or acetic (vinegar) flavours that at high levels, can be pretty awful!

When is a fault not a fault…?

Some wine “faults” aren’t actually faults at all. This is where picking true faults can get tricky, but once we’re finished here, you’ll be an expert!

Volatile Acidity (acetic acid)

This can be one of the most common wine faults, known as vinegar taint, but it is also a tool used by some high-quality winemakers to develop complexity in their flavour profiles.

Cast your mind back to this post, where I explain what Rob means when he talks about those “estery Penfolds-esque characters” in his Shiraz. It all comes down to a delicate balance.

Tartrate Crystals

These are mineral precipitates that form out of unfiltered, high mineral wines. They are little crystals sitting on the bottom of older bottles. They will cause you no harm. Just decant the wine leaving the sediment in the bottle.

Herbal Aromas 

Herbal aromas are typical parts of certain varietally-specific flavour profiles that can smell of grass, eucalyptus, or asparagus. To new or unfamiliar wine drinkers, these aromas can seem similar to sulphur or microbial wine faults.


Christmas is coming

Yes, as much as I try to deny it, it really is just around the corner!

We’re busy curating a lovely list of presents, that (along with our wines) will help make your Christmas shopping a piece of cake.

Keep an eye out on your email or come along to our Champagne Shopping Morning on Sunday 26th November to get first dibs!

2 Replies to “Wine faults…. and other things you won’t find in a bottle of Somerled wine!”

  1. A winemaker friend refers to tartrate crystals in his wines as ‘wine diamonds’. As a lot of his wine is unfiltered he sees them as a positive attribute.

    Congratulations and thanks so much for 300 posts! I don’t get to all of them straight away but it’s nice to sometimes sit back and catch up on the ones we’ve missed.

    Well done, and if you’re still up for it please keep them coming!

  2. I’ve also heard them referred to as this, Stan. I think it’s a perfect description for them!

    And thanks for the lovely words and for reading along with me… it’s been a pleasure writing them each week and I hope to write at least 300 more!

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