How to Recognize the Common Wine Faults?

The very first step in tasting a wine is its visual analysis. At first glance, you can already identify certain defects that will later be reflected on the nose or palate.

• Dull colour: indicates that the wine is unbalanced or lacks acidity.
• Whitish particles in white wine, or bluish particles in red wine: indicates an excess of iron and copper in the wine, due to poorly cleaned or maintained equipment.
• Brownish particles in red wines: the grapes were harvested after their optimal maturity or were already rotten.
• Slight effervescence: wine is said to be fizzy. This is due to a second fermentation in the bottle, which is not desired for still wines, or some carbon dioxide was trapped inside when the wine was bottled.
• White wine with a very dark yellow colour or red wine with a brown colour: it is very likely that the wine is oxidised.

If certain faults are not perceptible during the visual analysis, from the very first smell of the wine, certain aromas do not lie. It is a safe bet that these faults that can be perceived on the nose are unfortunately reflected on the palate. It is the organoleptic defects of the wine that affect both the olfactory and the gustatory analysis. Some of the wine's faults, however, are very disturbing to the nose, while they are hardly noticeable on the palate. A nose that is not clean will not necessarily taste.

The management of oxygen supply throughout the wine making process is not straightforward. The wine must have just the right amount of contact with oxygen. If it does not have enough oxygen, defects can form. If the oxygen supply is too intense, other types of unpleasant aromas will appear. Among the defects linked to a lack of oxygen, the most well-known is the following:

• Reduction: is manifested by a smell of struck match, boiled cabbage or rotten eggs. The wine has lacked oxygen during the vinification process. The colour of the wine also loses its brightness.

Of course, controlled oxygen intake helps to promote the complexity of the wine's aromas. However, too much oxygen can lead to the formation of defects in the wine. Among the main defects linked to excess oxygen, here are the most frequent ones:

• Rotten apple smell: it occurs when the ethanol in the wine is transformed into ethanal.
• Vinegar smell: it is due to prolonged oxidation, which has transformed the wine. The aromas can also be reminiscent of nail polish or nail polish remover and are referred to as volatile acidity, a problem that has arisen during the winemaking process.

In the world of wine, rot is not always negative. Indeed, noble rot, caused by the botrytis cinerea fungus, produces sweet wines of outstanding quality. However, under certain weather conditions, it can happen that noble rot does not develop and that grey rot takes over the grapes instead. The grapes are then lost. If the grapes are harvested and vinified anyway, they will produce wines without any fresh aroma, rotten wines. Unfortunately, this defect cannot be corrected.

Wine is a fragile and living product. Other defects can therefore occur for different reasons. Here are some of the recognisable defects you may encounter:

• Brettanomyces: this defect manifests itself by a strong smell of stable, barnyard, bandage, wet dog or burnt plastic. This is due to a yeast naturally present in the vineyards and in the cellars called brettanomyces. In small quantities it can be desired as it adds complexity to the wine.
• Maderized wine: the maderization of wine is due to poor storage of bottles. The bottles may have been stored upright, exposed to light, heat, or they may have been subjected to significant temperature changes. These elements are all fatal for the wine, whose structure is fragile. Smells of jammy or stewed fruit, rancid butter or caramel develop. In addition, the colour of white wine turns yellow, while that of red wine turns brown.
• Sulphur smell: sulphur dioxide, or SO2, is added to wine at various stages of its production. In order to stabilise the wine and ensure its preservation, sulphur dioxide is added at the bottling stage. Although this substance is beneficial to the wine, it should not be overused, otherwise the wine develops struck match or cooked cabbage aroma.

Some wines are deliberately oxidised and have an international reputation for their specific aromas of dried fruit, caramel and nuts. For some appellations, the oxidative character of the wine is desired. While this may be perceived as a defect, it does allow for the appearance of specific aromas that have made the reputation of certain appellations. Here is a list of wines that are voluntarily oxidised, but whose oxygen intake is nevertheless well controlled and mastered: Sherry, Vin Jaune, Rivesaltes, Banyuls and some orange wines.

Natural wines are wines that have undergone as little intervention as possible, both in the vineyard and in the cellar. Many of them have no added sulphur, which weakens their structure. Specific aromas develop, such as those of chard apples, a rancid taste or vinegar. Such a sourness on the palate would be considered by many as a defect. However, these aromas are well appreciated by those who like natural wines.