How to Tell if Your Wine Has Gone Bad

Not all wine is made equal, and not every bottle will keep in storage (after all, red wine vinegar was discovered when wine that had gone rancid). Sometimes when wine goes bad it’s obvious – from the colour changing to suddenly realising that your Pinot Gris has transitioned into a sparkling. Other times however, it’s a subtler that you aren’t able to put your finger on; all you know is that something isn’t right.

While many wine flaws are a little difficult to spot, it’s not impossible. To help you in the future, here are some tips on identifying the five most common ways your wine can go bad, and hopefully next time you come across a bad bottle, you can use this knowledge to get a decent one on the house!

1. Corked Wine

With the dominance of screw caps, it is less and less common to come across a corked wine in Australia, however, corking is still one of the most common issues affecting wine in older vintages and overseas. A wine can become corked when it is contaminated with cork taint – a type of fungi called TCA (246 Trichloranisole for the wine geeks out there) which creates a series of chemical reactions through the bottle or cask. TCA develops when certain fungi come into contact with chlorine based cleaning products and can very easily infect an entire winery or distillery. Since it’s discovery in the 1990s, most wineries have stopped the use of chlorine based sanitisers to prevent corking issues.

Though in no way harmful, corked wine does have a specific taste – it causes the flavour to be muted, flat and just slightly off. Some corked wines with a stronger fungi presence can taste soggy, wet and even a bit like rotten cardboard with an unpleasant smell. If you come across a corked wine, you likely will be able to tell from the first aromas and you won’t want to be taking a sip. Conservative estimates state that up to 5% of wine out there is corked – so keep an eye out as you are likely to come across one sooner or later!

2. Cooked Wine

If your bottle of red is tasting more like port than shiraz, there is a high chance it has been ‘cooked’. This wine flaw is exactly what it sounds like, a wine becomes cooked when the bottle is exposed to very high temperatures. This can be from sun exposure during transportation – on hot ship decks or sun drenched loading bays – or from being packed inside a sweaty metal container. Cooking a wine kills the intricacies in the flavour, leaving the bottle devoid of depth and complexity. This issue can also arise in your own storage of wine, by leaving it in a hot basement, garage, near a heater or in direct sunlight. Storing your wine in a temperature controlled wine fridge is the best way to prevent it from cooking.

The good news is, cooked wines are easy to spot in bottles with corks as the heat causes expansion in the bottle, driving the cork to poke out of the bottle neck by a few centimetres. A bottle with streaks of dried wine on the outside can also indicate cooking and a sniff test will reveal raisiny or stewed fruit aromas.

3. Oxidised Wine

Oxidation occurs all around us every day. If you take a bite from an apple and leave it on your desk for fifteen minutes, the flesh will begin to brown from oxidation. This is the chemical reaction that occurs when something comes into contact with oxygen and begins to break down. This same process can happen in your wine due for reasons, from cork shrinkage to poor storage. Oxidation in wine causes it to go stale and brown in colour, much like an apple. This means an oxidised wine is easy to spot and when tasted, it will present more like applesauce, a nutty burnt marshmallow or even cider vinegar. Oxidation can be a good thing though – in small quantities it rounds out harsh edges and improves flavour, body and texture; however too much of it will ruin any great wine.

4. Reduction in Wine

Almost the opposite of an oxidised wine, reduction in wine occurs before the wine is even opened, when it has not been exposed to enough oxygen during the production or maturation (whether this be in the winery or the cellar). Reduced wines have a distinctive flavour profile, often tasting like garlic, cabbage, or even burnt rubber and they can often have a pretty unpleasant sulphuric aroma too, almost like rotten eggs.

Wines that have been reduced however do have a chance, much of the time all you need to do is promptly decant the bottle. Let it breathe for a good hour and give it the oxygen it needs to sort itself out. Often this process will do the trick and make the wine more palatable. If you are something of an amateur scientist, you can do a quick home experiment to remedy the issue by dropping a copper coin into the decanter. This prompts the sulphur molecules to adhere themselves to the copper in the coin which should make the sulphur undetectable to the nose and the palate!

5. Brett

This is the common abbreviation for Brettanomyces, a form of yeast that is found in nearly all wineries. It is slightly misleading to refer to this as a flaw, because in small quantities, a touch of Brett can add interesting elements to a wine – bringing out earthy flavours that compliment the wines’ natural palate. Some wineries work with it purposefully to enhance and add complexity because when it is good, it adds an almost meaty flavour with floral top notes. However, it must be handled in carefully controlled amounts, because when it’s bad, it’s very bad, ruining the wine with wet dog-like flavours.

If you think your wine if suffering from any of these flaws, don’t be afraid to speak up and return the bottle or glass. These issues are common and you will no doubt come across a corked, cooked or oxidised bottle sooner or later. Your wine merchant will be very aware of all these flaws (and more!) and any merchant worth their salt will happily help you deal with the problem – likely with a new bottle!


At Grand Cru, we are the wine fridge experts and can provide you with state of the art wine fridges to keep and age your wine at the perfect temperature all year round.