Recognizing wine defects

When it comes to wine, unfortunately there are bottles out there that are defective and should not be consumed. Sometimes the problem originates in the winery, in its production or cellar management. Other times problems come from sources beyond the winemaker’s control, or from mishandling after the wine leaves the producer. Regardless, a defective wine is no fun.

Wine defects fall into two categories: flaws and faults. A flaw is something that makes the wine atypical, a slight variance in character from the norm. In this case, any minor flaw might be considered “complexity” and the wine could still be enjoyable. On the other hand, a fault is a major departure from the norm that spoils the wine and renders it undrinkable. A flaw that is extreme could easily fall into this category. There’s a fine line here as to when a flaw is too much.

Regardless of the intensity of the problem, most defects in wine show up on the nose rather than the palate, and since we sniff a wine before tasting it, we can avoid putting it into our mouths if the nose is “off.”

Most drinkers will not notice a defect unless it’s extreme. If you stick your nose in a wine and it smells like your dirty gym bag, you don’t have to be an expert to know there’s something wrong and you should not taste it.

Wine defects, and specifically odours, originate from different sources. Here are a few of the main ones.

Several defects result from extensive use of sulphur-containing compounds. One of the most common of these is sulphur dioxide, which has a pungent smell, leaving an unpleasant effect on the tissues of the nose and throat. Another is hydrogen sulphide, which smells like rotten eggs. Then there’s mercaptan. This very unpleasant odour sometimes smells like garlic.

Several wine defects result from the action of bacteria. One that I come across every now and then is butyric acid. This problem makes the wine smell like rancid butter or spoiled Camembert cheese. Lactic acid is an interesting problem resulting in a goaty or sauerkraut aroma. Acetic acid is a very common problem smelling specifically like vinegar.

There are many odour problems that result from other causes. One of the most prevalent is “corky.” The use of bad corks can result in TCA, or trichloroanisole, which renders the wine smelling musty like a damp basement. Another very common problem is oxidation, simply meaning the wine in question has been over-exposed to air. The wine usually smells tired or sherry-like. A wine that smells mouldy usually is caused by using mouldy grapes or barrels. While filtering a wine, sometimes the filter pads are not changed often enough and the result is a chalky, papery note on the nose. This defect is called “filter-pad.”

A really interesting fault is ethyl acetate, resulting from wine-spoiled yeast. Ladies will recognize this odour more often than men, as it resembles nail polish remover. Another fascinating fault is “geranium,” resulting from sorbic acid and smelling like the leaves of a geranium plant. A very common flaw, especially in California wines, is brettanomyces, better known as “brett.” The smell is very distinctive, like a barnyard or gamey horse aromas.

Hopefully I haven’t turned you off wine, talking about some of these defects. It’s good to be aware of some of the possibilities the next time you smell a wine that is “off.” Remember, life’s too short to drink bad wine.


Edward Finstein is a wine writer, award-winning author, TV and radio host, educator, judge

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