A disappointing yet possible scenario is to be at the best restaurant in the world, order their top wine, and when the sommelier gives you a taste, to find out that the wine is faulty. No one is necessarily to blame, but the restaurant has the responsibility to open another bottle nonetheless.
You might not like the wine because it is not to your taste or simply not very well made, but you cannot send the wine back unless it shows some of the following problems.
Bear in mind that it is possible to spot most of these faults with a sniff; to taste the (bad) wine is not needed. Even if a wine has a bouquet of petrol, tar, or some chemicals, it should always be in a pleasant way. The smell needs to be “clean”, and if not it is most likely faulty.
The first cause of flawed wines is corked wine, aka cork taint: trichloroanisole (lots of points in Scrabble) or TCA. It is a chemical component from a fungicide and it can be found in cork, wood, rubber, pipes etc. Therefore this ruining agent can come either from the cork or through it, and sometimes a whole winery can be affected. In this dramatic case the wine can be affected by TCA before bottling, so even a wine with a screw top can be corked. This is much more rare than a wine bottled with natural cork, but still possible.
On the nose it basically gives a strong cork smell to the wine, like a damp basement with a taste of wet paper. If you are at home and can’t send the bottle back, a way to save the wine is to pour it into a bowl over a plastic wrap. The polyethylene in the plastic will absorb the TCA component. This is most effective right after opening the bottle.
Happily, the percentage of wine that is corked is in constant decrease. As today it only affects around 2 percent of the world’s wines. Even in high quantities TCA is not harmful.
The second most common wine fault is oxidation – a prolonged contact with oxygen. This can come from a defective cork or damaged seal. Very often it is due to the cork being too dry, if the bottle was not stored correctly (http://macaudailytimes.com.mo/wine-storage.html). It is not uncommon in this part of the world to have an oxidised wine when ordering by the glass, as the bottle may have been open for several days. It is possible to identify an oxidised wine from the colour as it will show the same characteristics as an old wine: tawny/brown hue and a lack of brightness.
Lack of brightness will also be present on the nose and taste. It will be stale and flat with a lack of vibrant aromas, with a sherry-like flavours such as nuts and/or stewed fruits. Note that white wines oxidise faster than reds. Additionally it is possible for a cork to be very dry and break into pieces, yet the wine remains unspoiled.
Another issue facing this part of the world is excess heat, which sometimes comes with excess light. In the case of heat we say the wine is maderised – named after Madeira wine where the process consists of “cooking” the wine (leaving the barrels under the sun) and oxidising it. This brings flavours of cooked fruits and nutty aromas. Very often for a wine getting too much heat, the cork will expand and the wine gets oxidised as well.
Excess UV and even artificial lights are especially damaging for white wines, as they are most commonly bottled in non-tinted glass. The tannins present in red wines mostly provide extra protection.
In both cases there are no known ways of reversing this problem.
The last and fairly uncommon flaw in wine is the excess of sulfur dioxide. It is used in almost all wines to prevent fermentation and kill bacteria. It gives a rotten egg, old fart-like smell, coming from the mercaptan compound. It is most often encountered in cheap wines. If the smell is not unbearable it can be fixed by decanting.
Note that tartrate crystals (looking like shards of broken glass, sometimes present on the cork as well), as well as sediments are not a fault; they are natural by-products of wine. Both are harmless and can be removed by decanting. David Rouault
David Rouault is a professional classical musician, part time wine consultant and full time wine lover, holding WSET Level 3,
Certified Specialist of Wine and Introductory Sommelier diplomas. www.dionysos.com.mo