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How can you recognise possible defects in wine?

Although, thankfully, it’s not very common, it can be that when you open a bottle of wine you find that it has been affected in some way, and, therefore, it is not in the best condition for drinking.
Therefore, in today’s post we want to show you how to identify by sight, smell or taste some of the most common defects in wine, and where possible, show you how to solve them. Let’s get started!
Cómo reconocer los defectos que puede presentar el vino

Corked wine

Despite what it may seem, cork should not transmit any smell to the wine. If you smell an aroma of “damp, mushroomy” cork or wet cardboard in the wine, it is almost certain that it is because it has been contaminated by TCA, a type of compound produced by mould in the natural stopper, which is passed onto the wine when in contact with it in the bottle. If you are not sure if the wine is afflicted by this problem or not, the recommendation is to wait a little, as the aroma of corked wine gets stronger as time passes. The most common defect in the world is corked wine (it affects approximately 4% of bottles) and wines affected by it cannot be saved.

A vinegary flavour

This is the easiest defect of all to identify in wine. It is the classic “sour” aroma and it is due, technically, to a high level of volatile acidity that is due, in turn, to a mistake in the process of making or storing the wine, and it is caused by bacteria known as acetic bacteria. A wine with a taste of vinegar cannot easily be salvaged.

Oxidised wine

Excess oxygenation is caused by excessive contact between the wine and air and causes the flavour to be altered (some people talk about a smell of rotten apples) as ethanol – the alcohol that the wine contains – oxidises to form a molecule called ethanal or acetaldehyde. Also, the wine doesn’t look too good either (it loses brightness and goes brown as the substances that give it its red colour oxidise). The wine can be oxidised due to an error in its production or due to a mistake made in its storage, for example if it has been stored for too long at a high temperature or in direct light, and/or with the bottle in a vertical position (the cork dries out and oxygen gets in). An oxidised wine is also a wine that has been irredeemably ruined.

Smell of rotten eggs

An aroma of rotten eggs appears when the opposite occurs to the previous case, when the wine has suffered from a lack of oxygen in its production or ageing. You can detect it if you notice a smell of glue, burnt rubber or rotten egg when you open the bottle. It happens most frequently, although not solely, in young wines as the process of ageing wine in barrels helps to open them up and it can improve in some cases through decantation.

Dregs in wine

This is a solely visual fault as the appearance of sediment or dregs in wine is a perfectly natural process and is normal in wine. However, take care not to tip the dregs into the glasses, as they are slightly bitter: it is enough to allow the bottle to rest before drinking it so the sediment will fall to the bottom. You can also decant the wine.

Little crystals

As in the previous case, if you see small crystals in the wine, don’t worry. They appear because, during its production, the wine has not been properly stabilised or it has been made in a very respectful way without filtering: the technical name for these crystals is “tartrates” (they come from tartaric acid) and their appearance does not affect the aroma or taste of wine, so, don’t worry if you find them: it is safe to drink.

Excess sulphur

A smell of struck match or moth balls, a bitter taste or prickle and dryness in the throat are clear indicators that excess sulphur dioxide has wreaked havoc on the wine. The wine will also have lost brightness and red wines will go a brownish colour. The only solution is to open another bottle.


If you find little bubbles in non-sparkling wine (that’s to say, a still one) and you also think its appearance is a little more cloudy than you would expect, it may be possible that it is due to it undergoing an unintentional second fermentation in the bottle, as it was bottled with some residual sugar or malic acid, and the yeast or bacteria have been able to start working again. If the wine doesn’t taste unpleasant, you can drink it.


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