Taste Like A Pro, Wine Faults...


Reproduced from Year 5, Issue #26 of Spirito di Vino Asia...

Until now, this series has focused on the critical concepts that define wine style and quality and guide wine professionals to establish their scores.  Firstly, we saw that style relates to a “wine’s personality, ”.” and that quality is its “measure of excellence.” However, it may happen that wine is faulty, no matter its price point. To recognize it in wine is an essential skill through evaluation of appearance and taste. In this article, we review the most important.

Faults have a great many possible origins.  First, they can come from problems in the vineyard either because grapes are unripe or too ripe, and perhaps they are affected by various diseases or excess residues from pesticides, organic or conventional. Winemaking is an important source of taints due to the various metals or plastic materials used in winery equipment.  However, the most critical origin of faults is microbiological: from yeasts and or bacteria.

From its appearance, the wine can show bubbles (in the case of still wines), cloudiness, off-color or deposits.  Bubbles, usually large, are associated with refermentation in bottle after the wine has been bottled.  This is usually accompanied with cloudiness and an off-odor reminiscent of yeast. However, tiny bubbles and a spritzy texture might have been desired by the winemaker who injected a small amount of neutral gasses in the bottle at bottling to maintain the freshness of the wine as long as possible.  If such wine does not smell yeasty or milky and it is bright and clear, it is not faulty.  Some wines, especially whites and rosés, have deposits that resemble tiny pieces of glasses that look more like crystals than shards. These are most likely tartrates from the precipitation of tartaric acid salts and are harmless.

Most faults, however, are recognized through smell and taste.  The most important one being TCA, better known as cork taint.  The smell is similar to an old sofa, a moldy newspaper, or a wet dog and it suppresses the wine's aromas. It stems from the cork being infected by the bacteria “trichloral anisole.” A little-known fact is that TCA can also infect various equipment of the winery, including barrels and beams supporting the roofs and walls.  Therefore, it is technically possible for a wine sealed under screwcap to be TCA tainted.  Although this problem was quite common in the past, it is increasingly managed better, and we are likely to see less and fewer instances of it in the future.  Another issue with cork taint is that, let’s say on a scale of 1 to 10, a wine can be infected at a level 2, still showing the wine bouquet, albeit not as well as it should, and a very slight taint.  This is a tragedy for a winemaker because many people will think there is a problem with the winemaking and will never order it again.

Another fault that is increasingly observable, especially due to the “natural wines” trend, is that of volatile acidity, or VA.  The origin of this fault is acetic acid, and ethyl acetate and the affected wine smells of vinegar or nail polish.  In very small quantity, it can add a floral note to the wine, but all too often, it is distracting. Microbes produce VA, and it is the result of moldy grapes at harvest, some “wild” yeasts, poor hygiene in the cellar and during winemaking, and very low levels of sulfites in the wine.

Brettanomyces or the wild yeast that generate a “sweaty saddle” like smell to the wine is slightly more controversial than VA.  Brett, for short, in small amount is a positive to wine as it adds a “savory” aspect to the bouquet and it is often present in the wines of the “old world.”  In too large an amount, it is distracting and can smell too much like a band-aid or a sweaty horse. The source of such a yeast is poor hygiene of both fruit and equipment and very low levels of sulfites in the wine.

Lastly, some wines can have a sulphuric smell reminiscent of rotten eggs, cooking gas and burnt rubber.  These are due to volatile sulfur compounds developing because of an absence of oxygen during winemaking. Fermentation naturally produces tiny amounts of Sulphur in wine. These compounds increase when the yeast are starved of nutrients, most likely from low-quality fruits.

In the next article, we will review “natural” wines.