You’ll probably never stop enjoying this ‘pop’ noise when you open a nice bottle - indicating what a nice evening you’re about to spend. It might be ruined, however, by a flaw - either a major fault preventing any pleasure, or some kind of a small aroma which may be light, but unpleasant.

The good thing is, having a flawed bottle does not mean your whole case will also have it: Most faults happen in the bottle, not during winemaking. Let’s go through the possible flaws to help you recognise them next time it happens!

Girl sniffing out wine flaws

If you read this blog on a regular basis, you probably know that wine’s worst enemy is oxygen (if you want to know more about how to keep your wine, have a look here). This is why winemakers do everything it takes to avoid oxidation - at every step from harvest to bottling.

This condition also happens when a wine is kept open during several days, developing pronounced aroma of over ripened fruit and vinegar. Unfortunately, if this happens it is already too late to save the wine, and a sink will be the most appropriate place for it.

Wine oxidation over time

Talking about oxidation - have you ever wondered where the mention “contains sulphites”, that you see on nearly any wine bottle, comes from? Well, sulphites are just sulphur - what you find on matches. Sulphur actually helps winemakers control oxidation. Dosage is very important, as too much sulphur can lead to reduction (see below).

Reduction is the opposite of oxidation - a fault coming for a high level of sulphur, that has deprived wine from any oxygen for an extended period. While rotten egg is the most typical reduction aroma (yes, pretty awful…), you may also find cauliflower, onion or simply… sulphur.

This sounds pretty bad, but in most cases a vigorous twirl in a large carafe will make the wine breath and limit, if not remove, these unpleasant aroma.

Sulfur on matches

Trichloroanisole, aka cork taint, is a fault due to the cork being contaminated by chlorine, during cork cleaning. Natural wine aroma become are hidden by odour of humid wood or wet cardboard - or even mould. It is one of the easiest flaws to spot - and there is nothing you can do about it. You may return it to your shop, they will probably exchange it as a gesture of goodwill - we will do it no matter what.

All faults are not always external to wine: they can directly come from winemaking. If you taste some kind of bitterness, it is probably due to an excess of vegetal stuff (grape skin, leaves, stalks) during fermentation. If you spot animal or leather aroma or even sweat (!!), this is also due to a winemaking issue.

Full glass of corks

Brettanomyce is a natural yeast, present in most wines. While they usually provide pleasant aroma and add complexity (typical from Burgundy Pinot Noir), a high quantity can bring nasty flavours. As Anthony Hanson (MW) illustrated this in 1982: ‘Great Burgundy smells of shit’.

Wine drop composition

Volatile acidity is another possible fault, coming from acids produced during fermentation. As opposed to the acidity you have on the palate (which is often a good thing), you can actually smell this one which is similar to vinegar or nail polish. While it can sometimes benefit to specific wines such as sweet whites, it can become troublesome.

You should now be able to spot the possible flaws in a wine, even if you’d prefer avoid them as much as possible. They will however not necessarily be the cause of a bad surprise, as other factors come to play during a tasting - what you eat, what you smell and what you see may have implications as well.