The production of wine is like any other mass produced product, there will always be a few problems along the way. The skill is to reduce these to an absolute minimum, but the odd nasty will occasionally raise its head.
Wine problems can occur at so many stages during the winemaking process, and if left uncorrected will appear later on. Tasting a wine is subjective, determined not only by the wines character, but also the individuals likes and dislikes. Some wines will appear sweet to one person and dry to another, the field is broad.
So if you have just had that bottle of Merlot, with tasting notes on the back label that read something like, "ripe red fruit flavours with a savoury finish", did you recognize those characteristics? Perhaps you found notes of stewed prunes with demerara sugar instead. Whose tasting assessment was more accurate? Lots of questions, so let's see if there could be a fault lurking or whether the official tasting notes reflected a poetic licence of mythological proportions.
Faults in wine are subject to conjecture. What can generally be regarded as faults may actually be beneficial to certain styles, in fact many of the great wine styles of the world are based on faults of a kind. These include:
Champagne - a secondary fermentation in the bottle discovered by the monk Dom Perignon. Sauternes - the sweet wine get its character from mould on the grapes affected by Botrytis cinera, or noble rot as it's known. Tawny Port - a port that is aged in oak casks for an extended time thus undergoing oxidation. Vinho verde - goes through a malolactic fermentation which is used to soften wines with higher acidity. Flor sherry - the fortified high alcohol wine develops an aerobic yeast growth in the cask.
At lower concentrations, these faults can give depth and complexity, therefore do not appear as faults. On the other hand some characteristics are only faults when they are present in excess.
As wine contains alcohol and acidity, significant levels of bacteria are unable to grow and survive in it. Faulty wine may be unpleasant, but it will not harm you. Let's take a look at the major nasty faults which occur in wine.
Oxidation (O2): The #1 wine problem, whereby oxygen reacts with various components. In red wines, oxidation can be seen when the colour changes from red to brown, and the nose can become acetic and sour. Cork Taint: This used to be a big problem when most of the wines were sealed with corks, but is less so nowadays. A musty taint was imparted into the wine by a compound called 2,4,6 trichloroanisole (TCA) which came from mould growth on the cork bark. Sulfur Dioxide (SO2): The use of SO2 has always been used in winemaking, and plays a vital part in wine preservation, however, when used in excess it has a bad side. It can completely dominate the nose of a wine, and can lead to headaches or allergic reactions to those who are vulnerable, especially asthmatics. Hydrogen Sulphide (H2S): This potent fault is characterised by the smell of bad eggs. H2S will often react with other components in wine to form related compounds called Mercaptans. These Mercaptans have a range of unpleasant odours, such as 'wet dog hair', 'burnt rubber' or 'sweaty saddles'. H2S is primarily formed by yeast the during fermentation process. Volatile Acidity (VA): The term VA describes the presence of excessive amounts of acetic acid or a related compound, ethyl acetate. Acetic acid is the major compound in vinegar, so the aroma will notable, whilst the ethyl acetate is a main component in nail varnish remover. High acetic levels can also cause a sharpness on the palate.
As can be seen from this list of major wine faults - there are numerous others as well - making wine can be fraught with difficulties.
The use of high grade materials, such as stainless steel combined with good all round hygiene has no doubt reduced the incidence of many faults. The best winemaking skills and attention to detail during the fermentation process right through to bottling will limit bacterial growth.
Armed with a sensitive nose and clear palate you will now know how to detect wine faults, should they jump out of the bottle at you!
