Wine Glass over table

With a familiar wine, it is easy to detect an off-smell or a funky taste. Winemakers always notice something unusual about their own wines, as do most tasting room hosts.

With an unfamiliar wine, it is not always so easy. My husband and I love trying new wines, and on a good number of occasions we’ve wondered: is the Syrah we’ve just purchased intentionally made rustic, or does it have too much brett and so is flawed? Or, are the notes of baked apples in this dry Chenin a sign of premature aging, or is it winemaker’s style?

So how do we tell apart an intentional style in wine from a flawed execution?

The easiest perhaps is cork taint – an undeniable fault in wine, which everyone agrees on. Whenever a wine smells of wet cardboard or a damp musty basement, that’s a fault. Responsible for cork taint is 2,4,6-trichloroanisole, or TCA, one of the most odor-intense compounds, perceptible at tiny amounts. As the name implies, corks are the major source of TCA. But any wood, including barrels, wooden structures or pallets in the cellar, could also give wine that musty, moldy smell. TCA can be addressed by e.g. using a different cork or closure or replacing old wood in the cellar.

Another obvious fault is the smell of boiled cabbage, rotten vegetables, garlic, onion, burnt rubber, and natural gas. This signals about the presence of mercaptan or disulfides from yeast byproducts. If detected at the winery, the fault can be addressed by doing copper fining. If detected in a bottle, it’ll have to go down the drain.

When it comes to volatile acidity, or VA, it becomes a fault only at levels exceeding a sensory threshold. VA is recognized by the smell of vinegar, scientifically known as acetic acid. The latter is present in all wine. But its increased levels can be produced by some yeasts during fermentation, by bacteria during storage when tanks are not full or in a bottle when extra oxygen sips through a faulty cork. So elevated levels of VA do indicate a problem with wine quality.

The presence of ethyl acetate, another oxidation-type fault, makes one’s conclusion about intent vs. execution a bit more complicated. While the smell of nail polish remover or solvent doesn’t come across as very appealing, in low amounts ethyl acetate is not a bad thing. Especially in late harvest or botrytized wines, it enhances fruity and floral aromas and adds complexity.

Similar to the two compounds above, acetaldehyde is present in all wine – it is a direct oxidation product of ethanol (alcohol). At low concentrations, it can add pleasant fruity aromas. At higher concentrations, the pungent smell of over-ripe or bruised apples, dry straw, nuts or sherry tells us it’s a fault. However, in some specific styles of wine, such as sherry and vin jaune from Jura, the compound is deliberately encouraged at high levels. So here we have to ask ourselves if the wine style and the aromas belong together.

With brettanomyces, or brett, a naturally occurring and highly prevalent yeast, questions multiply. Brett produces both bad and good compounds. The smells of band aid, barnyard, or rotten meat associated with 4-ethylphenol are considered to be bad. Aromas of bacon, spice, cloves, smoke and leather associated with 4-ethylguiacol are appealing to many wine drinkers, as long as they don’t overpower the wine’s varietal character. Moreover, some strains of brett are considered to be part of terroir, as many Bordeaux and Southern Rhone winemakers and wine lovers will attest. Brett can develop in wine after primary fermentation. It loves very ripe grapes, thick skinned varieties, residual sugar, high alcohol, and lower acidity. Winemakers can control its levels by using sulphur dioxide, filtering, and deciding on when to pick grapes.

The examples above show that wine defects are a complex subject. Some undeniably signal about flawed winemaking or problematic storage. Others become faults only if they exceed a sensory threshold: if we don’t smell them, they’re not a problem. Yet, others are considered to be part of site specificity or a wine style.

Ultimately, our tolerance is determined by individual sensitivity and taste. Do we prefer a perfectly clean wine or a wine with personality and perhaps a bit of peculiarity?

The upcoming seminar on wine defects is a rare opportunity to calibrate your nose on several wine defects in one setting. Join two wine experts and fellow Wine Women members at DeLoach Vineyards on August 14, and gain the confidence that few possess.

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